From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0DBEDC2BA83 for ; Wed, 12 Feb 2020 15:39:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C6C8206ED for ; Wed, 12 Feb 2020 15:39:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Ah1bdHor" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728652AbgBLPjI (ORCPT ); Wed, 12 Feb 2020 10:39:08 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:40554 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728596AbgBLPjG (ORCPT ); Wed, 12 Feb 2020 10:39:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581521938; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=Pi8LTt8KWX0akczSg++lnC0sX1A9TuymEvUWidA/JpI=; b=Ah1bdHorl87xY7ztstbRIAOzfc0q03mSrLwzLU3h32q3vH2f2EkEBvbT24WgGR0F3KcUGL bXC/Lgh1sh04wJL6f2/bIAC9eOsCPFWF8zbZUgHnLM5sVZK7JrmtfPVX+CRqWqHz1Unjm6 uM74OATiIx/iMFmE3jNLVM1A0wwCml4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-256-n84MaRjcMe6tr7kYUhgNUQ-1; Wed, 12 Feb 2020 10:38:53 -0500 X-MC-Unique: n84MaRjcMe6tr7kYUhgNUQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CF42F800E21; Wed, 12 Feb 2020 15:38:51 +0000 (UTC) Received: from llong.com (dhcp-17-59.bos.redhat.com [10.18.17.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id DD8636E40A; Wed, 12 Feb 2020 15:38:50 +0000 (UTC) From: Waiman Long To: Peter Zijlstra , Ingo Molnar , Will Deacon Cc: linux-kernel@vger.kernel.org, Bart Van Assche , Waiman Long Subject: [PATCH-tip 2/3] locking/lockdep: Extract CONFIG_PROVE_LOCKING code out to lockdep_prove.c Date: Wed, 12 Feb 2020 10:38:27 -0500 Message-Id: <20200212153828.346-3-longman@redhat.com> In-Reply-To: <20200212153828.346-1-longman@redhat.com> References: <20200212153828.346-1-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org About half of the lockdep code in lockdep.c are surrounded by the CONFIG_PROVE_LOCKING conditional compilation macro. There are several of those conditional compilation blocks making it hard to figure it out if a certain function is only used for CONFIG_PROVE_LOCKING or not. That leads to all sort of build problems when modifying the lockdep code. To make life easier for future update, most of the relevant CONFIG_PROVE_LOCKING code are now extracted out to the lockdep_prove.c file making it clear which function is for CONFIG_PROVE_LOCKING and which is not. There are still a number of small CONFIG_PROVE_LOCKING blocks left in lockdep.c, but they are easy to be identified. This is just a code relocation patch. There is no functional change. Signed-off-by: Waiman Long --- kernel/locking/lockdep.c | 3216 ++------------------------------ kernel/locking/lockdep_prove.c | 2820 ++++++++++++++++++++++++++++ 2 files changed, 3025 insertions(+), 3011 deletions(-) create mode 100644 kernel/locking/lockdep_prove.c diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 3dad36e2187b..417c0616d791 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -449,104 +449,6 @@ static void print_lockdep_off(const char *bug_msg) unsigned long nr_stack_trace_entries; -#ifdef CONFIG_PROVE_LOCKING -/** - * struct lock_trace - single stack backtrace - * @hash_entry: Entry in a stack_trace_hash[] list. - * @hash: jhash() of @entries. - * @nr_entries: Number of entries in @entries. - * @entries: Actual stack backtrace. - */ -struct lock_trace { - struct hlist_node hash_entry; - u32 hash; - u32 nr_entries; - unsigned long entries[0] __aligned(sizeof(unsigned long)); -}; -#define LOCK_TRACE_SIZE_IN_LONGS \ - (sizeof(struct lock_trace) / sizeof(unsigned long)) -/* - * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock. - */ -static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; -static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE]; - -static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2) -{ - return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries && - memcmp(t1->entries, t2->entries, - t1->nr_entries * sizeof(t1->entries[0])) == 0; -} - -static struct lock_trace *save_trace(void) -{ - struct lock_trace *trace, *t2; - struct hlist_head *hash_head; - u32 hash; - int max_entries; - - BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE); - BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES); - - trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries); - max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries - - LOCK_TRACE_SIZE_IN_LONGS; - - if (max_entries <= 0) { - if (!debug_locks_off_graph_unlock()) - return NULL; - - print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); - dump_stack(); - - return NULL; - } - trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3); - - hash = jhash(trace->entries, trace->nr_entries * - sizeof(trace->entries[0]), 0); - trace->hash = hash; - hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1)); - hlist_for_each_entry(t2, hash_head, hash_entry) { - if (traces_identical(trace, t2)) - return t2; - } - nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries; - hlist_add_head(&trace->hash_entry, hash_head); - - return trace; -} - -/* Return the number of stack traces in the stack_trace[] array. */ -u64 lockdep_stack_trace_count(void) -{ - struct lock_trace *trace; - u64 c = 0; - int i; - - for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) { - hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) { - c++; - } - } - - return c; -} - -/* Return the number of stack hash chains that have at least one stack trace. */ -u64 lockdep_stack_hash_count(void) -{ - u64 c = 0; - int i; - - for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) - if (!hlist_empty(&stack_trace_hash[i])) - c++; - - return c; -} -#endif - unsigned int nr_hardirq_chains; unsigned int nr_softirq_chains; unsigned int nr_process_chains; @@ -559,26 +461,6 @@ unsigned int max_lockdep_depth; DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); #endif -#ifdef CONFIG_PROVE_LOCKING -/* - * Locking printouts: - */ - -#define __USAGE(__STATE) \ - [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ - [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ - [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ - [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", - -static const char *usage_str[] = -{ -#define LOCKDEP_STATE(__STATE) __USAGE(__STATE) -#include "lockdep_states.h" -#undef LOCKDEP_STATE - [LOCK_USED] = "INITIAL USE", -}; -#endif - const char *__get_key_name(const struct lockdep_subclass_key *key, char *str) { return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); @@ -885,8 +767,49 @@ static bool assign_lock_key(struct lockdep_map *lock) return true; } +#ifdef CONFIG_PROVE_LOCKING +#include "lockdep_prove.c" +#else + +static inline int +mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) +{ + return 1; +} + +static inline unsigned int task_irq_context(struct task_struct *task) +{ + return 0; +} + +static inline int separate_irq_context(struct task_struct *curr, + struct held_lock *hlock) +{ + return 0; +} + +static inline int validate_chain(struct task_struct *curr, + struct held_lock *hlock, + int chain_head, u64 chain_key) +{ + return 1; +} + +static inline void init_chain_block_buckets(void) { } +static inline void check_flags(unsigned long flags) { } +static inline void remove_class_from_lock_chains(struct pending_free *pf, + struct lock_class *class) { } +#endif /* CONFIG_PROVE_LOCKING */ + #ifdef CONFIG_DEBUG_LOCKDEP +#ifndef check_lock_chain_key +static inline bool check_lock_chain_key(struct lock_chain *chain) +{ + return true; +} +#endif + /* Check whether element @e occurs in list @h */ static bool in_list(struct list_head *e, struct list_head *h) { @@ -937,33 +860,6 @@ static bool class_lock_list_valid(struct lock_class *c, struct list_head *h) return true; } -#ifdef CONFIG_PROVE_LOCKING -static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; -#endif - -static bool check_lock_chain_key(struct lock_chain *chain) -{ -#ifdef CONFIG_PROVE_LOCKING - u64 chain_key = INITIAL_CHAIN_KEY; - int i; - - for (i = chain->base; i < chain->base + chain->depth; i++) - chain_key = iterate_chain_key(chain_key, chain_hlocks[i]); - /* - * The 'unsigned long long' casts avoid that a compiler warning - * is reported when building tools/lib/lockdep. - */ - if (chain->chain_key != chain_key) { - printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n", - (unsigned long long)(chain - lock_chains), - (unsigned long long)chain->chain_key, - (unsigned long long)chain_key); - return false; - } -#endif - return true; -} - static bool in_any_zapped_class_list(struct lock_class *class) { struct pending_free *pf; @@ -1127,2817 +1023,208 @@ void lockdep_register_key(struct lock_class_key *key) raw_local_irq_save(flags); if (!graph_lock()) goto restore_irqs; - hlist_for_each_entry_rcu(k, hash_head, hash_entry) { - if (WARN_ON_ONCE(k == key)) - goto out_unlock; - } - hlist_add_head_rcu(&key->hash_entry, hash_head); -out_unlock: - graph_unlock(); -restore_irqs: - raw_local_irq_restore(flags); -} -EXPORT_SYMBOL_GPL(lockdep_register_key); - -/* Check whether a key has been registered as a dynamic key. */ -static bool is_dynamic_key(const struct lock_class_key *key) -{ - struct hlist_head *hash_head; - struct lock_class_key *k; - bool found = false; - - if (WARN_ON_ONCE(static_obj(key))) - return false; - - /* - * If lock debugging is disabled lock_keys_hash[] may contain - * pointers to memory that has already been freed. Avoid triggering - * a use-after-free in that case by returning early. - */ - if (!debug_locks) - return true; - - hash_head = keyhashentry(key); - - rcu_read_lock(); - hlist_for_each_entry_rcu(k, hash_head, hash_entry) { - if (k == key) { - found = true; - break; - } - } - rcu_read_unlock(); - - return found; -} - -/* - * Register a lock's class in the hash-table, if the class is not present - * yet. Otherwise we look it up. We cache the result in the lock object - * itself, so actual lookup of the hash should be once per lock object. - */ -static struct lock_class * -register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) -{ - struct lockdep_subclass_key *key; - struct hlist_head *hash_head; - struct lock_class *class; - - DEBUG_LOCKS_WARN_ON(!irqs_disabled()); - - class = look_up_lock_class(lock, subclass); - if (likely(class)) - goto out_set_class_cache; - - if (!lock->key) { - if (!assign_lock_key(lock)) - return NULL; - } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) { - return NULL; - } - - key = lock->key->subkeys + subclass; - hash_head = classhashentry(key); - - if (!graph_lock()) { - return NULL; - } - /* - * We have to do the hash-walk again, to avoid races - * with another CPU: - */ - hlist_for_each_entry_rcu(class, hash_head, hash_entry) { - if (class->key == key) - goto out_unlock_set; - } - - init_data_structures_once(); - - /* Allocate a new lock class and add it to the hash. */ - class = list_first_entry_or_null(&free_lock_classes, typeof(*class), - lock_entry); - if (!class) { - if (!debug_locks_off_graph_unlock()) { - return NULL; - } - - print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); - dump_stack(); - return NULL; - } - nr_lock_classes++; - __set_bit(class - lock_classes, lock_classes_in_use); - debug_atomic_inc(nr_unused_locks); - class->key = key; - class->name = lock->name; - class->subclass = subclass; - WARN_ON_ONCE(!list_empty(&class->locks_before)); - WARN_ON_ONCE(!list_empty(&class->locks_after)); - class->name_version = count_matching_names(class); - /* - * We use RCU's safe list-add method to make - * parallel walking of the hash-list safe: - */ - hlist_add_head_rcu(&class->hash_entry, hash_head); - /* - * Remove the class from the free list and add it to the global list - * of classes. - */ - list_move_tail(&class->lock_entry, &all_lock_classes); - - if (verbose(class)) { - graph_unlock(); - - printk("\nnew class %px: %s", class->key, class->name); - if (class->name_version > 1) - printk(KERN_CONT "#%d", class->name_version); - printk(KERN_CONT "\n"); - dump_stack(); - - if (!graph_lock()) { - return NULL; - } - } -out_unlock_set: - graph_unlock(); - -out_set_class_cache: - if (!subclass || force) - lock->class_cache[0] = class; - else if (subclass < NR_LOCKDEP_CACHING_CLASSES) - lock->class_cache[subclass] = class; - - /* - * Hash collision, did we smoke some? We found a class with a matching - * hash but the subclass -- which is hashed in -- didn't match. - */ - if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) - return NULL; - - return class; -} - -#ifdef CONFIG_PROVE_LOCKING -/* - * Allocate a lockdep entry. (assumes the graph_lock held, returns - * with NULL on failure) - */ -static struct lock_list *alloc_list_entry(void) -{ - int idx = find_first_zero_bit(list_entries_in_use, - ARRAY_SIZE(list_entries)); - - if (idx >= ARRAY_SIZE(list_entries)) { - if (!debug_locks_off_graph_unlock()) - return NULL; - - print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); - dump_stack(); - return NULL; - } - nr_list_entries++; - __set_bit(idx, list_entries_in_use); - return list_entries + idx; -} - -/* - * Add a new dependency to the head of the list: - */ -static int add_lock_to_list(struct lock_class *this, - struct lock_class *links_to, struct list_head *head, - unsigned long ip, int distance, - const struct lock_trace *trace) -{ - struct lock_list *entry; - /* - * Lock not present yet - get a new dependency struct and - * add it to the list: - */ - entry = alloc_list_entry(); - if (!entry) - return 0; - - entry->class = this; - entry->links_to = links_to; - entry->distance = distance; - entry->trace = trace; - /* - * Both allocation and removal are done under the graph lock; but - * iteration is under RCU-sched; see look_up_lock_class() and - * lockdep_free_key_range(). - */ - list_add_tail_rcu(&entry->entry, head); - - return 1; -} - -/* - * For good efficiency of modular, we use power of 2 - */ -#define MAX_CIRCULAR_QUEUE_SIZE 4096UL -#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) - -/* - * The circular_queue and helpers are used to implement graph - * breadth-first search (BFS) algorithm, by which we can determine - * whether there is a path from a lock to another. In deadlock checks, - * a path from the next lock to be acquired to a previous held lock - * indicates that adding the -> lock dependency will - * produce a circle in the graph. Breadth-first search instead of - * depth-first search is used in order to find the shortest (circular) - * path. - */ -struct circular_queue { - struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE]; - unsigned int front, rear; -}; - -static struct circular_queue lock_cq; - -unsigned int max_bfs_queue_depth; - -static unsigned int lockdep_dependency_gen_id; - -static inline void __cq_init(struct circular_queue *cq) -{ - cq->front = cq->rear = 0; - lockdep_dependency_gen_id++; -} - -static inline int __cq_empty(struct circular_queue *cq) -{ - return (cq->front == cq->rear); -} - -static inline int __cq_full(struct circular_queue *cq) -{ - return ((cq->rear + 1) & CQ_MASK) == cq->front; -} - -static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem) -{ - if (__cq_full(cq)) - return -1; - - cq->element[cq->rear] = elem; - cq->rear = (cq->rear + 1) & CQ_MASK; - return 0; -} - -/* - * Dequeue an element from the circular_queue, return a lock_list if - * the queue is not empty, or NULL if otherwise. - */ -static inline struct lock_list * __cq_dequeue(struct circular_queue *cq) -{ - struct lock_list * lock; - - if (__cq_empty(cq)) - return NULL; - - lock = cq->element[cq->front]; - cq->front = (cq->front + 1) & CQ_MASK; - - return lock; -} - -static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) -{ - return (cq->rear - cq->front) & CQ_MASK; -} - -static inline void mark_lock_accessed(struct lock_list *lock, - struct lock_list *parent) -{ - unsigned long nr; - - nr = lock - list_entries; - WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ - lock->parent = parent; - lock->class->dep_gen_id = lockdep_dependency_gen_id; -} - -static inline unsigned long lock_accessed(struct lock_list *lock) -{ - unsigned long nr; - - nr = lock - list_entries; - WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ - return lock->class->dep_gen_id == lockdep_dependency_gen_id; -} - -static inline struct lock_list *get_lock_parent(struct lock_list *child) -{ - return child->parent; -} - -static inline int get_lock_depth(struct lock_list *child) -{ - int depth = 0; - struct lock_list *parent; - - while ((parent = get_lock_parent(child))) { - child = parent; - depth++; - } - return depth; -} - -/* - * Return the forward or backward dependency list. - * - * @lock: the lock_list to get its class's dependency list - * @offset: the offset to struct lock_class to determine whether it is - * locks_after or locks_before - */ -static inline struct list_head *get_dep_list(struct lock_list *lock, int offset) -{ - void *lock_class = lock->class; - - return lock_class + offset; -} - -/* - * Forward- or backward-dependency search, used for both circular dependency - * checking and hardirq-unsafe/softirq-unsafe checking. - */ -static int __bfs(struct lock_list *source_entry, - void *data, - int (*match)(struct lock_list *entry, void *data), - struct lock_list **target_entry, - int offset) -{ - struct lock_list *entry; - struct lock_list *lock; - struct list_head *head; - struct circular_queue *cq = &lock_cq; - int ret = 1; - - if (match(source_entry, data)) { - *target_entry = source_entry; - ret = 0; - goto exit; - } - - head = get_dep_list(source_entry, offset); - if (list_empty(head)) - goto exit; - - __cq_init(cq); - __cq_enqueue(cq, source_entry); - - while ((lock = __cq_dequeue(cq))) { - - if (!lock->class) { - ret = -2; - goto exit; - } - - head = get_dep_list(lock, offset); - - DEBUG_LOCKS_WARN_ON(!irqs_disabled()); - - list_for_each_entry_rcu(entry, head, entry) { - if (!lock_accessed(entry)) { - unsigned int cq_depth; - mark_lock_accessed(entry, lock); - if (match(entry, data)) { - *target_entry = entry; - ret = 0; - goto exit; - } - - if (__cq_enqueue(cq, entry)) { - ret = -1; - goto exit; - } - cq_depth = __cq_get_elem_count(cq); - if (max_bfs_queue_depth < cq_depth) - max_bfs_queue_depth = cq_depth; - } - } - } -exit: - return ret; -} - -static inline int __bfs_forwards(struct lock_list *src_entry, - void *data, - int (*match)(struct lock_list *entry, void *data), - struct lock_list **target_entry) -{ - return __bfs(src_entry, data, match, target_entry, - offsetof(struct lock_class, locks_after)); - -} - -static inline int __bfs_backwards(struct lock_list *src_entry, - void *data, - int (*match)(struct lock_list *entry, void *data), - struct lock_list **target_entry) -{ - return __bfs(src_entry, data, match, target_entry, - offsetof(struct lock_class, locks_before)); - -} - -static void print_lock_trace(const struct lock_trace *trace, - unsigned int spaces) -{ - stack_trace_print(trace->entries, trace->nr_entries, spaces); -} - -/* - * Print a dependency chain entry (this is only done when a deadlock - * has been detected): - */ -static noinline void -print_circular_bug_entry(struct lock_list *target, int depth) -{ - if (debug_locks_silent) - return; - printk("\n-> #%u", depth); - print_lock_name(target->class); - printk(KERN_CONT ":\n"); - print_lock_trace(target->trace, 6); -} - -static void -print_circular_lock_scenario(struct held_lock *src, - struct held_lock *tgt, - struct lock_list *prt) -{ - struct lock_class *source = hlock_class(src); - struct lock_class *target = hlock_class(tgt); - struct lock_class *parent = prt->class; - - /* - * A direct locking problem where unsafe_class lock is taken - * directly by safe_class lock, then all we need to show - * is the deadlock scenario, as it is obvious that the - * unsafe lock is taken under the safe lock. - * - * But if there is a chain instead, where the safe lock takes - * an intermediate lock (middle_class) where this lock is - * not the same as the safe lock, then the lock chain is - * used to describe the problem. Otherwise we would need - * to show a different CPU case for each link in the chain - * from the safe_class lock to the unsafe_class lock. - */ - if (parent != source) { - printk("Chain exists of:\n "); - __print_lock_name(source); - printk(KERN_CONT " --> "); - __print_lock_name(parent); - printk(KERN_CONT " --> "); - __print_lock_name(target); - printk(KERN_CONT "\n\n"); - } - - printk(" Possible unsafe locking scenario:\n\n"); - printk(" CPU0 CPU1\n"); - printk(" ---- ----\n"); - printk(" lock("); - __print_lock_name(target); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(parent); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(target); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(source); - printk(KERN_CONT ");\n"); - printk("\n *** DEADLOCK ***\n\n"); -} - -/* - * When a circular dependency is detected, print the - * header first: - */ -static noinline void -print_circular_bug_header(struct lock_list *entry, unsigned int depth, - struct held_lock *check_src, - struct held_lock *check_tgt) -{ - struct task_struct *curr = current; - - if (debug_locks_silent) - return; - - pr_warn("\n"); - pr_warn("======================================================\n"); - pr_warn("WARNING: possible circular locking dependency detected\n"); - print_kernel_ident(); - pr_warn("------------------------------------------------------\n"); - pr_warn("%s/%d is trying to acquire lock:\n", - curr->comm, task_pid_nr(curr)); - print_lock(check_src); - - pr_warn("\nbut task is already holding lock:\n"); - - print_lock(check_tgt); - pr_warn("\nwhich lock already depends on the new lock.\n\n"); - pr_warn("\nthe existing dependency chain (in reverse order) is:\n"); - - print_circular_bug_entry(entry, depth); -} - -static inline int class_equal(struct lock_list *entry, void *data) -{ - return entry->class == data; -} - -static noinline void print_circular_bug(struct lock_list *this, - struct lock_list *target, - struct held_lock *check_src, - struct held_lock *check_tgt) -{ - struct task_struct *curr = current; - struct lock_list *parent; - struct lock_list *first_parent; - int depth; - - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return; - - this->trace = save_trace(); - if (!this->trace) - return; - - depth = get_lock_depth(target); - - print_circular_bug_header(target, depth, check_src, check_tgt); - - parent = get_lock_parent(target); - first_parent = parent; - - while (parent) { - print_circular_bug_entry(parent, --depth); - parent = get_lock_parent(parent); - } - - printk("\nother info that might help us debug this:\n\n"); - print_circular_lock_scenario(check_src, check_tgt, - first_parent); - - lockdep_print_held_locks(curr); - - printk("\nstack backtrace:\n"); - dump_stack(); -} - -static noinline void print_bfs_bug(int ret) -{ - if (!debug_locks_off_graph_unlock()) - return; - - /* - * Breadth-first-search failed, graph got corrupted? - */ - WARN(1, "lockdep bfs error:%d\n", ret); -} - -static int noop_count(struct lock_list *entry, void *data) -{ - (*(unsigned long *)data)++; - return 0; -} - -static unsigned long __lockdep_count_forward_deps(struct lock_list *this) -{ - unsigned long count = 0; - struct lock_list *uninitialized_var(target_entry); - - __bfs_forwards(this, (void *)&count, noop_count, &target_entry); - - return count; -} -unsigned long lockdep_count_forward_deps(struct lock_class *class) -{ - unsigned long ret, flags; - struct lock_list this; - - this.parent = NULL; - this.class = class; - - raw_local_irq_save(flags); - arch_spin_lock(&lockdep_lock); - ret = __lockdep_count_forward_deps(&this); - arch_spin_unlock(&lockdep_lock); - raw_local_irq_restore(flags); - - return ret; -} - -static unsigned long __lockdep_count_backward_deps(struct lock_list *this) -{ - unsigned long count = 0; - struct lock_list *uninitialized_var(target_entry); - - __bfs_backwards(this, (void *)&count, noop_count, &target_entry); - - return count; -} - -unsigned long lockdep_count_backward_deps(struct lock_class *class) -{ - unsigned long ret, flags; - struct lock_list this; - - this.parent = NULL; - this.class = class; - - raw_local_irq_save(flags); - arch_spin_lock(&lockdep_lock); - ret = __lockdep_count_backward_deps(&this); - arch_spin_unlock(&lockdep_lock); - raw_local_irq_restore(flags); - - return ret; -} - -/* - * Check that the dependency graph starting at can lead to - * or not. Print an error and return 0 if it does. - */ -static noinline int -check_path(struct lock_class *target, struct lock_list *src_entry, - struct lock_list **target_entry) -{ - int ret; - - ret = __bfs_forwards(src_entry, (void *)target, class_equal, - target_entry); - - if (unlikely(ret < 0)) - print_bfs_bug(ret); - - return ret; -} - -/* - * Prove that the dependency graph starting at can not - * lead to . If it can, there is a circle when adding - * -> dependency. - * - * Print an error and return 0 if it does. - */ -static noinline int -check_noncircular(struct held_lock *src, struct held_lock *target, - struct lock_trace **const trace) -{ - int ret; - struct lock_list *uninitialized_var(target_entry); - struct lock_list src_entry = { - .class = hlock_class(src), - .parent = NULL, - }; - - debug_atomic_inc(nr_cyclic_checks); - - ret = check_path(hlock_class(target), &src_entry, &target_entry); - - if (unlikely(!ret)) { - if (!*trace) { - /* - * If save_trace fails here, the printing might - * trigger a WARN but because of the !nr_entries it - * should not do bad things. - */ - *trace = save_trace(); - } - - print_circular_bug(&src_entry, target_entry, src, target); - } - - return ret; -} - -#ifdef CONFIG_LOCKDEP_SMALL -/* - * Check that the dependency graph starting at can lead to - * or not. If it can, -> dependency is already - * in the graph. - * - * Print an error and return 2 if it does or 1 if it does not. - */ -static noinline int -check_redundant(struct held_lock *src, struct held_lock *target) -{ - int ret; - struct lock_list *uninitialized_var(target_entry); - struct lock_list src_entry = { - .class = hlock_class(src), - .parent = NULL, - }; - - debug_atomic_inc(nr_redundant_checks); - - ret = check_path(hlock_class(target), &src_entry, &target_entry); - - if (!ret) { - debug_atomic_inc(nr_redundant); - ret = 2; - } else if (ret < 0) - ret = 0; - - return ret; -} -#endif - -#ifdef CONFIG_TRACE_IRQFLAGS - -static inline int usage_accumulate(struct lock_list *entry, void *mask) -{ - *(unsigned long *)mask |= entry->class->usage_mask; - - return 0; -} - -/* - * Forwards and backwards subgraph searching, for the purposes of - * proving that two subgraphs can be connected by a new dependency - * without creating any illegal irq-safe -> irq-unsafe lock dependency. - */ - -static inline int usage_match(struct lock_list *entry, void *mask) -{ - return entry->class->usage_mask & *(unsigned long *)mask; -} - -/* - * Find a node in the forwards-direction dependency sub-graph starting - * at @root->class that matches @bit. - * - * Return 0 if such a node exists in the subgraph, and put that node - * into *@target_entry. - * - * Return 1 otherwise and keep *@target_entry unchanged. - * Return <0 on error. - */ -static int -find_usage_forwards(struct lock_list *root, unsigned long usage_mask, - struct lock_list **target_entry) -{ - int result; - - debug_atomic_inc(nr_find_usage_forwards_checks); - - result = __bfs_forwards(root, &usage_mask, usage_match, target_entry); - - return result; -} - -/* - * Find a node in the backwards-direction dependency sub-graph starting - * at @root->class that matches @bit. - * - * Return 0 if such a node exists in the subgraph, and put that node - * into *@target_entry. - * - * Return 1 otherwise and keep *@target_entry unchanged. - * Return <0 on error. - */ -static int -find_usage_backwards(struct lock_list *root, unsigned long usage_mask, - struct lock_list **target_entry) -{ - int result; - - debug_atomic_inc(nr_find_usage_backwards_checks); - - result = __bfs_backwards(root, &usage_mask, usage_match, target_entry); - - return result; -} - -static void print_lock_class_header(struct lock_class *class, int depth) -{ - int bit; - - printk("%*s->", depth, ""); - print_lock_name(class); -#ifdef CONFIG_DEBUG_LOCKDEP - printk(KERN_CONT " ops: %lu", debug_class_ops_read(class)); -#endif - printk(KERN_CONT " {\n"); - - for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { - if (class->usage_mask & (1 << bit)) { - int len = depth; - - len += printk("%*s %s", depth, "", usage_str[bit]); - len += printk(KERN_CONT " at:\n"); - print_lock_trace(class->usage_traces[bit], len); - } - } - printk("%*s }\n", depth, ""); - - printk("%*s ... key at: [<%px>] %pS\n", - depth, "", class->key, class->key); -} - -/* - * printk the shortest lock dependencies from @start to @end in reverse order: - */ -static void __used -print_shortest_lock_dependencies(struct lock_list *leaf, - struct lock_list *root) -{ - struct lock_list *entry = leaf; - int depth; - - /*compute depth from generated tree by BFS*/ - depth = get_lock_depth(leaf); - - do { - print_lock_class_header(entry->class, depth); - printk("%*s ... acquired at:\n", depth, ""); - print_lock_trace(entry->trace, 2); - printk("\n"); - - if (depth == 0 && (entry != root)) { - printk("lockdep:%s bad path found in chain graph\n", __func__); - break; - } - - entry = get_lock_parent(entry); - depth--; - } while (entry && (depth >= 0)); -} - -static void -print_irq_lock_scenario(struct lock_list *safe_entry, - struct lock_list *unsafe_entry, - struct lock_class *prev_class, - struct lock_class *next_class) -{ - struct lock_class *safe_class = safe_entry->class; - struct lock_class *unsafe_class = unsafe_entry->class; - struct lock_class *middle_class = prev_class; - - if (middle_class == safe_class) - middle_class = next_class; - - /* - * A direct locking problem where unsafe_class lock is taken - * directly by safe_class lock, then all we need to show - * is the deadlock scenario, as it is obvious that the - * unsafe lock is taken under the safe lock. - * - * But if there is a chain instead, where the safe lock takes - * an intermediate lock (middle_class) where this lock is - * not the same as the safe lock, then the lock chain is - * used to describe the problem. Otherwise we would need - * to show a different CPU case for each link in the chain - * from the safe_class lock to the unsafe_class lock. - */ - if (middle_class != unsafe_class) { - printk("Chain exists of:\n "); - __print_lock_name(safe_class); - printk(KERN_CONT " --> "); - __print_lock_name(middle_class); - printk(KERN_CONT " --> "); - __print_lock_name(unsafe_class); - printk(KERN_CONT "\n\n"); - } - - printk(" Possible interrupt unsafe locking scenario:\n\n"); - printk(" CPU0 CPU1\n"); - printk(" ---- ----\n"); - printk(" lock("); - __print_lock_name(unsafe_class); - printk(KERN_CONT ");\n"); - printk(" local_irq_disable();\n"); - printk(" lock("); - __print_lock_name(safe_class); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(middle_class); - printk(KERN_CONT ");\n"); - printk(" \n"); - printk(" lock("); - __print_lock_name(safe_class); - printk(KERN_CONT ");\n"); - printk("\n *** DEADLOCK ***\n\n"); -} - -static void -print_bad_irq_dependency(struct task_struct *curr, - struct lock_list *prev_root, - struct lock_list *next_root, - struct lock_list *backwards_entry, - struct lock_list *forwards_entry, - struct held_lock *prev, - struct held_lock *next, - enum lock_usage_bit bit1, - enum lock_usage_bit bit2, - const char *irqclass) -{ - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return; - - pr_warn("\n"); - pr_warn("=====================================================\n"); - pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", - irqclass, irqclass); - print_kernel_ident(); - pr_warn("-----------------------------------------------------\n"); - pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", - curr->comm, task_pid_nr(curr), - curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, - curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, - curr->hardirqs_enabled, - curr->softirqs_enabled); - print_lock(next); - - pr_warn("\nand this task is already holding:\n"); - print_lock(prev); - pr_warn("which would create a new lock dependency:\n"); - print_lock_name(hlock_class(prev)); - pr_cont(" ->"); - print_lock_name(hlock_class(next)); - pr_cont("\n"); - - pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", - irqclass); - print_lock_name(backwards_entry->class); - pr_warn("\n... which became %s-irq-safe at:\n", irqclass); - - print_lock_trace(backwards_entry->class->usage_traces[bit1], 1); - - pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); - print_lock_name(forwards_entry->class); - pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); - pr_warn("..."); - - print_lock_trace(forwards_entry->class->usage_traces[bit2], 1); - - pr_warn("\nother info that might help us debug this:\n\n"); - print_irq_lock_scenario(backwards_entry, forwards_entry, - hlock_class(prev), hlock_class(next)); - - lockdep_print_held_locks(curr); - - pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); - prev_root->trace = save_trace(); - if (!prev_root->trace) - return; - print_shortest_lock_dependencies(backwards_entry, prev_root); - - pr_warn("\nthe dependencies between the lock to be acquired"); - pr_warn(" and %s-irq-unsafe lock:\n", irqclass); - next_root->trace = save_trace(); - if (!next_root->trace) - return; - print_shortest_lock_dependencies(forwards_entry, next_root); - - pr_warn("\nstack backtrace:\n"); - dump_stack(); -} - -static const char *state_names[] = { -#define LOCKDEP_STATE(__STATE) \ - __stringify(__STATE), -#include "lockdep_states.h" -#undef LOCKDEP_STATE -}; - -static const char *state_rnames[] = { -#define LOCKDEP_STATE(__STATE) \ - __stringify(__STATE)"-READ", -#include "lockdep_states.h" -#undef LOCKDEP_STATE -}; - -static inline const char *state_name(enum lock_usage_bit bit) -{ - if (bit & LOCK_USAGE_READ_MASK) - return state_rnames[bit >> LOCK_USAGE_DIR_MASK]; - else - return state_names[bit >> LOCK_USAGE_DIR_MASK]; -} - -/* - * The bit number is encoded like: - * - * bit0: 0 exclusive, 1 read lock - * bit1: 0 used in irq, 1 irq enabled - * bit2-n: state - */ -static int exclusive_bit(int new_bit) -{ - int state = new_bit & LOCK_USAGE_STATE_MASK; - int dir = new_bit & LOCK_USAGE_DIR_MASK; - - /* - * keep state, bit flip the direction and strip read. - */ - return state | (dir ^ LOCK_USAGE_DIR_MASK); -} - -/* - * Observe that when given a bitmask where each bitnr is encoded as above, a - * right shift of the mask transforms the individual bitnrs as -1 and - * conversely, a left shift transforms into +1 for the individual bitnrs. - * - * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can - * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0) - * instead by subtracting the bit number by 2, or shifting the mask right by 2. - * - * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2. - * - * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is - * all bits set) and recompose with bitnr1 flipped. - */ -static unsigned long invert_dir_mask(unsigned long mask) -{ - unsigned long excl = 0; - - /* Invert dir */ - excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK; - excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK; - - return excl; -} - -/* - * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all - * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). - * And then mask out all bitnr0. - */ -static unsigned long exclusive_mask(unsigned long mask) -{ - unsigned long excl = invert_dir_mask(mask); - - /* Strip read */ - excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK; - excl &= ~LOCKF_IRQ_READ; - - return excl; -} - -/* - * Retrieve the _possible_ original mask to which @mask is - * exclusive. Ie: this is the opposite of exclusive_mask(). - * Note that 2 possible original bits can match an exclusive - * bit: one has LOCK_USAGE_READ_MASK set, the other has it - * cleared. So both are returned for each exclusive bit. - */ -static unsigned long original_mask(unsigned long mask) -{ - unsigned long excl = invert_dir_mask(mask); - - /* Include read in existing usages */ - excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK; - - return excl; -} - -/* - * Find the first pair of bit match between an original - * usage mask and an exclusive usage mask. - */ -static int find_exclusive_match(unsigned long mask, - unsigned long excl_mask, - enum lock_usage_bit *bitp, - enum lock_usage_bit *excl_bitp) -{ - int bit, excl; - - for_each_set_bit(bit, &mask, LOCK_USED) { - excl = exclusive_bit(bit); - if (excl_mask & lock_flag(excl)) { - *bitp = bit; - *excl_bitp = excl; - return 0; - } - } - return -1; -} - -/* - * Prove that the new dependency does not connect a hardirq-safe(-read) - * lock with a hardirq-unsafe lock - to achieve this we search - * the backwards-subgraph starting at , and the - * forwards-subgraph starting at : - */ -static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next) -{ - unsigned long usage_mask = 0, forward_mask, backward_mask; - enum lock_usage_bit forward_bit = 0, backward_bit = 0; - struct lock_list *uninitialized_var(target_entry1); - struct lock_list *uninitialized_var(target_entry); - struct lock_list this, that; - int ret; - - /* - * Step 1: gather all hard/soft IRQs usages backward in an - * accumulated usage mask. - */ - this.parent = NULL; - this.class = hlock_class(prev); - - ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL); - if (ret < 0) { - print_bfs_bug(ret); - return 0; - } - - usage_mask &= LOCKF_USED_IN_IRQ_ALL; - if (!usage_mask) - return 1; - - /* - * Step 2: find exclusive uses forward that match the previous - * backward accumulated mask. - */ - forward_mask = exclusive_mask(usage_mask); - - that.parent = NULL; - that.class = hlock_class(next); - - ret = find_usage_forwards(&that, forward_mask, &target_entry1); - if (ret < 0) { - print_bfs_bug(ret); - return 0; - } - if (ret == 1) - return ret; - - /* - * Step 3: we found a bad match! Now retrieve a lock from the backward - * list whose usage mask matches the exclusive usage mask from the - * lock found on the forward list. - */ - backward_mask = original_mask(target_entry1->class->usage_mask); - - ret = find_usage_backwards(&this, backward_mask, &target_entry); - if (ret < 0) { - print_bfs_bug(ret); - return 0; - } - if (DEBUG_LOCKS_WARN_ON(ret == 1)) - return 1; - - /* - * Step 4: narrow down to a pair of incompatible usage bits - * and report it. - */ - ret = find_exclusive_match(target_entry->class->usage_mask, - target_entry1->class->usage_mask, - &backward_bit, &forward_bit); - if (DEBUG_LOCKS_WARN_ON(ret == -1)) - return 1; - - print_bad_irq_dependency(curr, &this, &that, - target_entry, target_entry1, - prev, next, - backward_bit, forward_bit, - state_name(backward_bit)); - - return 0; -} - -#else - -static inline int check_irq_usage(struct task_struct *curr, - struct held_lock *prev, struct held_lock *next) -{ - return 1; -} -#endif /* CONFIG_TRACE_IRQFLAGS */ - -static void inc_chains(int irq_context) -{ - if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) - nr_hardirq_chains++; - else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) - nr_softirq_chains++; - else - nr_process_chains++; -} - -static void dec_chains(int irq_context) -{ - if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) - nr_hardirq_chains--; - else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) - nr_softirq_chains--; - else - nr_process_chains--; -} - -static void -print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv) -{ - struct lock_class *next = hlock_class(nxt); - struct lock_class *prev = hlock_class(prv); - - printk(" Possible unsafe locking scenario:\n\n"); - printk(" CPU0\n"); - printk(" ----\n"); - printk(" lock("); - __print_lock_name(prev); - printk(KERN_CONT ");\n"); - printk(" lock("); - __print_lock_name(next); - printk(KERN_CONT ");\n"); - printk("\n *** DEADLOCK ***\n\n"); - printk(" May be due to missing lock nesting notation\n\n"); -} - -static void -print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next) -{ - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return; - - pr_warn("\n"); - pr_warn("============================================\n"); - pr_warn("WARNING: possible recursive locking detected\n"); - print_kernel_ident(); - pr_warn("--------------------------------------------\n"); - pr_warn("%s/%d is trying to acquire lock:\n", - curr->comm, task_pid_nr(curr)); - print_lock(next); - pr_warn("\nbut task is already holding lock:\n"); - print_lock(prev); - - pr_warn("\nother info that might help us debug this:\n"); - print_deadlock_scenario(next, prev); - lockdep_print_held_locks(curr); - - pr_warn("\nstack backtrace:\n"); - dump_stack(); -} - -/* - * Check whether we are holding such a class already. - * - * (Note that this has to be done separately, because the graph cannot - * detect such classes of deadlocks.) - * - * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read - */ -static int -check_deadlock(struct task_struct *curr, struct held_lock *next) -{ - struct held_lock *prev; - struct held_lock *nest = NULL; - int i; - - for (i = 0; i < curr->lockdep_depth; i++) { - prev = curr->held_locks + i; - - if (prev->instance == next->nest_lock) - nest = prev; - - if (hlock_class(prev) != hlock_class(next)) - continue; - - /* - * Allow read-after-read recursion of the same - * lock class (i.e. read_lock(lock)+read_lock(lock)): - */ - if ((next->read == 2) && prev->read) - return 2; - - /* - * We're holding the nest_lock, which serializes this lock's - * nesting behaviour. - */ - if (nest) - return 2; - - print_deadlock_bug(curr, prev, next); - return 0; - } - return 1; -} - -/* - * There was a chain-cache miss, and we are about to add a new dependency - * to a previous lock. We validate the following rules: - * - * - would the adding of the -> dependency create a - * circular dependency in the graph? [== circular deadlock] - * - * - does the new prev->next dependency connect any hardirq-safe lock - * (in the full backwards-subgraph starting at ) with any - * hardirq-unsafe lock (in the full forwards-subgraph starting at - * )? [== illegal lock inversion with hardirq contexts] - * - * - does the new prev->next dependency connect any softirq-safe lock - * (in the full backwards-subgraph starting at ) with any - * softirq-unsafe lock (in the full forwards-subgraph starting at - * )? [== illegal lock inversion with softirq contexts] - * - * any of these scenarios could lead to a deadlock. - * - * Then if all the validations pass, we add the forwards and backwards - * dependency. - */ -static int -check_prev_add(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next, int distance, - struct lock_trace **const trace) -{ - struct lock_list *entry; - int ret; - - if (!hlock_class(prev)->key || !hlock_class(next)->key) { - /* - * The warning statements below may trigger a use-after-free - * of the class name. It is better to trigger a use-after free - * and to have the class name most of the time instead of not - * having the class name available. - */ - WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key, - "Detected use-after-free of lock class %px/%s\n", - hlock_class(prev), - hlock_class(prev)->name); - WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key, - "Detected use-after-free of lock class %px/%s\n", - hlock_class(next), - hlock_class(next)->name); - return 2; - } - - /* - * Prove that the new -> dependency would not - * create a circular dependency in the graph. (We do this by - * a breadth-first search into the graph starting at , - * and check whether we can reach .) - * - * The search is limited by the size of the circular queue (i.e., - * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes - * in the graph whose neighbours are to be checked. - */ - ret = check_noncircular(next, prev, trace); - if (unlikely(ret <= 0)) - return 0; - - if (!check_irq_usage(curr, prev, next)) - return 0; - - /* - * For recursive read-locks we do all the dependency checks, - * but we dont store read-triggered dependencies (only - * write-triggered dependencies). This ensures that only the - * write-side dependencies matter, and that if for example a - * write-lock never takes any other locks, then the reads are - * equivalent to a NOP. - */ - if (next->read == 2 || prev->read == 2) - return 1; - /* - * Is the -> dependency already present? - * - * (this may occur even though this is a new chain: consider - * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 - * chains - the second one will be new, but L1 already has - * L2 added to its dependency list, due to the first chain.) - */ - list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { - if (entry->class == hlock_class(next)) { - if (distance == 1) - entry->distance = 1; - return 1; - } - } - -#ifdef CONFIG_LOCKDEP_SMALL - /* - * Is the -> link redundant? - */ - ret = check_redundant(prev, next); - if (ret != 1) - return ret; -#endif - - if (!*trace) { - *trace = save_trace(); - if (!*trace) - return 0; - } - - /* - * Ok, all validations passed, add the new lock - * to the previous lock's dependency list: - */ - ret = add_lock_to_list(hlock_class(next), hlock_class(prev), - &hlock_class(prev)->locks_after, - next->acquire_ip, distance, *trace); - - if (!ret) - return 0; - - ret = add_lock_to_list(hlock_class(prev), hlock_class(next), - &hlock_class(next)->locks_before, - next->acquire_ip, distance, *trace); - if (!ret) - return 0; - - return 2; -} - -/* - * Add the dependency to all directly-previous locks that are 'relevant'. - * The ones that are relevant are (in increasing distance from curr): - * all consecutive trylock entries and the final non-trylock entry - or - * the end of this context's lock-chain - whichever comes first. - */ -static int -check_prevs_add(struct task_struct *curr, struct held_lock *next) -{ - struct lock_trace *trace = NULL; - int depth = curr->lockdep_depth; - struct held_lock *hlock; - - /* - * Debugging checks. - * - * Depth must not be zero for a non-head lock: - */ - if (!depth) - goto out_bug; - /* - * At least two relevant locks must exist for this - * to be a head: - */ - if (curr->held_locks[depth].irq_context != - curr->held_locks[depth-1].irq_context) - goto out_bug; - - for (;;) { - int distance = curr->lockdep_depth - depth + 1; - hlock = curr->held_locks + depth - 1; - - /* - * Only non-recursive-read entries get new dependencies - * added: - */ - if (hlock->read != 2 && hlock->check) { - int ret = check_prev_add(curr, hlock, next, distance, - &trace); - if (!ret) - return 0; - - /* - * Stop after the first non-trylock entry, - * as non-trylock entries have added their - * own direct dependencies already, so this - * lock is connected to them indirectly: - */ - if (!hlock->trylock) - break; - } - - depth--; - /* - * End of lock-stack? - */ - if (!depth) - break; - /* - * Stop the search if we cross into another context: - */ - if (curr->held_locks[depth].irq_context != - curr->held_locks[depth-1].irq_context) - break; - } - return 1; -out_bug: - if (!debug_locks_off_graph_unlock()) - return 0; - - /* - * Clearly we all shouldn't be here, but since we made it we - * can reliable say we messed up our state. See the above two - * gotos for reasons why we could possibly end up here. - */ - WARN_ON(1); - - return 0; -} - -struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; -static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS); -static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; -unsigned long nr_zapped_lock_chains; -unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */ -unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */ -unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */ - -/* - * The first 2 chain_hlocks entries in the chain block in the bucket - * list contains the following meta data: - * - * entry[0]: - * Bit 15 - always set to 1 (it is not a class index) - * Bits 0-14 - upper 15 bits of the next block index - * entry[1] - lower 16 bits of next block index - * - * A next block index of all 1 bits means it is the end of the list. - * - * On the unsized bucket (bucket-0), the 3rd and 4th entries contain - * the chain block size: - * - * entry[2] - upper 16 bits of the chain block size - * entry[3] - lower 16 bits of the chain block size - */ -#define MAX_CHAIN_BUCKETS 16 -#define CHAIN_BLK_FLAG (1U << 15) -#define CHAIN_BLK_LIST_END 0xFFFFU - -static int chain_block_buckets[MAX_CHAIN_BUCKETS]; - -static inline int size_to_bucket(int size) -{ - if (size > MAX_CHAIN_BUCKETS) - return 0; - - return size - 1; -} - -/* - * Iterate all the chain blocks in a bucket. - */ -#define for_each_chain_block(bucket, prev, curr) \ - for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \ - (curr) >= 0; \ - (prev) = (curr), (curr) = chain_block_next(curr)) - -/* - * next block or -1 - */ -static inline int chain_block_next(int offset) -{ - int next = chain_hlocks[offset]; - - WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG)); - - if (next == CHAIN_BLK_LIST_END) - return -1; - - next &= ~CHAIN_BLK_FLAG; - next <<= 16; - next |= chain_hlocks[offset + 1]; - - return next; -} - -/* - * bucket-0 only - */ -static inline int chain_block_size(int offset) -{ - return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3]; -} - -static inline void init_chain_block(int offset, int next, int bucket, int size) -{ - chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG; - chain_hlocks[offset + 1] = (u16)next; - - if (size && !bucket) { - chain_hlocks[offset + 2] = size >> 16; - chain_hlocks[offset + 3] = (u16)size; - } -} - -static inline void add_chain_block(int offset, int size) -{ - int bucket = size_to_bucket(size); - int next = chain_block_buckets[bucket]; - int prev, curr; - - if (unlikely(size < 2)) { - /* - * We can't store single entries on the freelist. Leak them. - * - * One possible way out would be to uniquely mark them, other - * than with CHAIN_BLK_FLAG, such that we can recover them when - * the block before it is re-added. - */ - if (size) - nr_lost_chain_hlocks++; - return; - } - - nr_free_chain_hlocks += size; - if (!bucket) { - nr_large_chain_blocks++; - - /* - * Variable sized, sort large to small. - */ - for_each_chain_block(0, prev, curr) { - if (size >= chain_block_size(curr)) - break; - } - init_chain_block(offset, curr, 0, size); - if (prev < 0) - chain_block_buckets[0] = offset; - else - init_chain_block(prev, offset, 0, 0); - return; - } - /* - * Fixed size, add to head. - */ - init_chain_block(offset, next, bucket, size); - chain_block_buckets[bucket] = offset; -} - -/* - * Only the first block in the list can be deleted. - * - * For the variable size bucket[0], the first block (the largest one) is - * returned, broken up and put back into the pool. So if a chain block of - * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be - * queued up after the primordial chain block and never be used until the - * hlock entries in the primordial chain block is almost used up. That - * causes fragmentation and reduce allocation efficiency. That can be - * monitored by looking at the "large chain blocks" number in lockdep_stats. - */ -static inline void del_chain_block(int bucket, int size, int next) -{ - nr_free_chain_hlocks -= size; - chain_block_buckets[bucket] = next; - - if (!bucket) - nr_large_chain_blocks--; -} - -static void init_chain_block_buckets(void) -{ - int i; - - for (i = 0; i < MAX_CHAIN_BUCKETS; i++) - chain_block_buckets[i] = -1; - - add_chain_block(0, ARRAY_SIZE(chain_hlocks)); -} - -/* - * Return offset of a chain block of the right size or -1 if not found. - * - * Fairly simple worst-fit allocator with the addition of a number of size - * specific free lists. - */ -static int alloc_chain_hlocks(int req) -{ - int bucket, curr, size; - - /* - * We rely on the MSB to act as an escape bit to denote freelist - * pointers. Make sure this bit isn't set in 'normal' class_idx usage. - */ - BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG); - - init_data_structures_once(); - - if (nr_free_chain_hlocks < req) - return -1; - - /* - * We require a minimum of 2 (u16) entries to encode a freelist - * 'pointer'. - */ - req = max(req, 2); - bucket = size_to_bucket(req); - curr = chain_block_buckets[bucket]; - - if (bucket) { - if (curr >= 0) { - del_chain_block(bucket, req, chain_block_next(curr)); - return curr; - } - /* Try bucket 0 */ - curr = chain_block_buckets[0]; - } - - /* - * The variable sized freelist is sorted by size; the first entry is - * the largest. Use it if it fits. - */ - if (curr >= 0) { - size = chain_block_size(curr); - if (likely(size >= req)) { - del_chain_block(0, size, chain_block_next(curr)); - add_chain_block(curr + req, size - req); - return curr; - } - } - - /* - * Last resort, split a block in a larger sized bucket. - */ - for (size = MAX_CHAIN_BUCKETS; size > req; size--) { - bucket = size_to_bucket(size); - curr = chain_block_buckets[bucket]; - if (curr < 0) - continue; - - del_chain_block(bucket, size, chain_block_next(curr)); - add_chain_block(curr + req, size - req); - return curr; - } - - return -1; -} - -static inline void free_chain_hlocks(int base, int size) -{ - add_chain_block(base, max(size, 2)); -} - -struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) -{ - return lock_classes + chain_hlocks[chain->base + i]; -} - -/* - * Returns the index of the first held_lock of the current chain - */ -static inline int get_first_held_lock(struct task_struct *curr, - struct held_lock *hlock) -{ - int i; - struct held_lock *hlock_curr; - - for (i = curr->lockdep_depth - 1; i >= 0; i--) { - hlock_curr = curr->held_locks + i; - if (hlock_curr->irq_context != hlock->irq_context) - break; - - } - - return ++i; -} - -#ifdef CONFIG_DEBUG_LOCKDEP -/* - * Returns the next chain_key iteration - */ -static u64 print_chain_key_iteration(int class_idx, u64 chain_key) -{ - u64 new_chain_key = iterate_chain_key(chain_key, class_idx); - - printk(" class_idx:%d -> chain_key:%016Lx", - class_idx, - (unsigned long long)new_chain_key); - return new_chain_key; -} - -static void -print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) -{ - struct held_lock *hlock; - u64 chain_key = INITIAL_CHAIN_KEY; - int depth = curr->lockdep_depth; - int i = get_first_held_lock(curr, hlock_next); - - printk("depth: %u (irq_context %u)\n", depth - i + 1, - hlock_next->irq_context); - for (; i < depth; i++) { - hlock = curr->held_locks + i; - chain_key = print_chain_key_iteration(hlock->class_idx, chain_key); - - print_lock(hlock); - } - - print_chain_key_iteration(hlock_next->class_idx, chain_key); - print_lock(hlock_next); -} - -static void print_chain_keys_chain(struct lock_chain *chain) -{ - int i; - u64 chain_key = INITIAL_CHAIN_KEY; - int class_id; - - printk("depth: %u\n", chain->depth); - for (i = 0; i < chain->depth; i++) { - class_id = chain_hlocks[chain->base + i]; - chain_key = print_chain_key_iteration(class_id, chain_key); - - print_lock_name(lock_classes + class_id); - printk("\n"); - } -} - -static void print_collision(struct task_struct *curr, - struct held_lock *hlock_next, - struct lock_chain *chain) -{ - pr_warn("\n"); - pr_warn("============================\n"); - pr_warn("WARNING: chain_key collision\n"); - print_kernel_ident(); - pr_warn("----------------------------\n"); - pr_warn("%s/%d: ", current->comm, task_pid_nr(current)); - pr_warn("Hash chain already cached but the contents don't match!\n"); - - pr_warn("Held locks:"); - print_chain_keys_held_locks(curr, hlock_next); - - pr_warn("Locks in cached chain:"); - print_chain_keys_chain(chain); - - pr_warn("\nstack backtrace:\n"); - dump_stack(); -} -#endif - -/* - * Checks whether the chain and the current held locks are consistent - * in depth and also in content. If they are not it most likely means - * that there was a collision during the calculation of the chain_key. - * Returns: 0 not passed, 1 passed - */ -static int check_no_collision(struct task_struct *curr, - struct held_lock *hlock, - struct lock_chain *chain) -{ -#ifdef CONFIG_DEBUG_LOCKDEP - int i, j, id; - - i = get_first_held_lock(curr, hlock); - - if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { - print_collision(curr, hlock, chain); - return 0; - } - - for (j = 0; j < chain->depth - 1; j++, i++) { - id = curr->held_locks[i].class_idx; - - if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { - print_collision(curr, hlock, chain); - return 0; - } - } -#endif - return 1; -} - -/* - * Given an index that is >= -1, return the index of the next lock chain. - * Return -2 if there is no next lock chain. - */ -long lockdep_next_lockchain(long i) -{ - i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1); - return i < ARRAY_SIZE(lock_chains) ? i : -2; -} - -unsigned long lock_chain_count(void) -{ - return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains)); -} - -/* Must be called with the graph lock held. */ -static struct lock_chain *alloc_lock_chain(void) -{ - int idx = find_first_zero_bit(lock_chains_in_use, - ARRAY_SIZE(lock_chains)); - - if (unlikely(idx >= ARRAY_SIZE(lock_chains))) - return NULL; - __set_bit(idx, lock_chains_in_use); - return lock_chains + idx; -} - -/* - * Adds a dependency chain into chain hashtable. And must be called with - * graph_lock held. - * - * Return 0 if fail, and graph_lock is released. - * Return 1 if succeed, with graph_lock held. - */ -static inline int add_chain_cache(struct task_struct *curr, - struct held_lock *hlock, - u64 chain_key) -{ - struct lock_class *class = hlock_class(hlock); - struct hlist_head *hash_head = chainhashentry(chain_key); - struct lock_chain *chain; - int i, j; - - /* - * The caller must hold the graph lock, ensure we've got IRQs - * disabled to make this an IRQ-safe lock.. for recursion reasons - * lockdep won't complain about its own locking errors. - */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return 0; - - chain = alloc_lock_chain(); - if (!chain) { - if (!debug_locks_off_graph_unlock()) - return 0; - - print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); - dump_stack(); - return 0; - } - chain->chain_key = chain_key; - chain->irq_context = hlock->irq_context; - i = get_first_held_lock(curr, hlock); - chain->depth = curr->lockdep_depth + 1 - i; - - BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks)); - BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks)); - BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes)); - - j = alloc_chain_hlocks(chain->depth); - if (j < 0) { - if (!debug_locks_off_graph_unlock()) - return 0; - - print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); - dump_stack(); - return 0; - } - - chain->base = j; - for (j = 0; j < chain->depth - 1; j++, i++) { - int lock_id = curr->held_locks[i].class_idx; - - chain_hlocks[chain->base + j] = lock_id; - } - chain_hlocks[chain->base + j] = class - lock_classes; - hlist_add_head_rcu(&chain->entry, hash_head); - debug_atomic_inc(chain_lookup_misses); - inc_chains(chain->irq_context); - - return 1; -} - -/* - * Look up a dependency chain. Must be called with either the graph lock or - * the RCU read lock held. - */ -static inline struct lock_chain *lookup_chain_cache(u64 chain_key) -{ - struct hlist_head *hash_head = chainhashentry(chain_key); - struct lock_chain *chain; - - hlist_for_each_entry_rcu(chain, hash_head, entry) { - if (READ_ONCE(chain->chain_key) == chain_key) { - debug_atomic_inc(chain_lookup_hits); - return chain; - } - } - return NULL; -} - -/* - * If the key is not present yet in dependency chain cache then - * add it and return 1 - in this case the new dependency chain is - * validated. If the key is already hashed, return 0. - * (On return with 1 graph_lock is held.) - */ -static inline int lookup_chain_cache_add(struct task_struct *curr, - struct held_lock *hlock, - u64 chain_key) -{ - struct lock_class *class = hlock_class(hlock); - struct lock_chain *chain = lookup_chain_cache(chain_key); - - if (chain) { -cache_hit: - if (!check_no_collision(curr, hlock, chain)) - return 0; - - if (very_verbose(class)) { - printk("\nhash chain already cached, key: " - "%016Lx tail class: [%px] %s\n", - (unsigned long long)chain_key, - class->key, class->name); - } - - return 0; - } - - if (very_verbose(class)) { - printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n", - (unsigned long long)chain_key, class->key, class->name); - } - - if (!graph_lock()) - return 0; - - /* - * We have to walk the chain again locked - to avoid duplicates: - */ - chain = lookup_chain_cache(chain_key); - if (chain) { - graph_unlock(); - goto cache_hit; - } - - if (!add_chain_cache(curr, hlock, chain_key)) - return 0; - - return 1; -} - -static int validate_chain(struct task_struct *curr, - struct held_lock *hlock, - int chain_head, u64 chain_key) -{ - /* - * Trylock needs to maintain the stack of held locks, but it - * does not add new dependencies, because trylock can be done - * in any order. - * - * We look up the chain_key and do the O(N^2) check and update of - * the dependencies only if this is a new dependency chain. - * (If lookup_chain_cache_add() return with 1 it acquires - * graph_lock for us) - */ - if (!hlock->trylock && hlock->check && - lookup_chain_cache_add(curr, hlock, chain_key)) { - /* - * Check whether last held lock: - * - * - is irq-safe, if this lock is irq-unsafe - * - is softirq-safe, if this lock is hardirq-unsafe - * - * And check whether the new lock's dependency graph - * could lead back to the previous lock: - * - * - within the current held-lock stack - * - across our accumulated lock dependency records - * - * any of these scenarios could lead to a deadlock. - */ - /* - * The simple case: does the current hold the same lock - * already? - */ - int ret = check_deadlock(curr, hlock); - - if (!ret) - return 0; - /* - * Mark recursive read, as we jump over it when - * building dependencies (just like we jump over - * trylock entries): - */ - if (ret == 2) - hlock->read = 2; - /* - * Add dependency only if this lock is not the head - * of the chain, and if it's not a secondary read-lock: - */ - if (!chain_head && ret != 2) { - if (!check_prevs_add(curr, hlock)) - return 0; - } - - graph_unlock(); - } else { - /* after lookup_chain_cache_add(): */ - if (unlikely(!debug_locks)) - return 0; - } - - return 1; -} -#else -static inline int validate_chain(struct task_struct *curr, - struct held_lock *hlock, - int chain_head, u64 chain_key) -{ - return 1; -} - -static void init_chain_block_buckets(void) { } -#endif /* CONFIG_PROVE_LOCKING */ - -/* - * We are building curr_chain_key incrementally, so double-check - * it from scratch, to make sure that it's done correctly: - */ -static void check_chain_key(struct task_struct *curr) -{ -#ifdef CONFIG_DEBUG_LOCKDEP - struct held_lock *hlock, *prev_hlock = NULL; - unsigned int i; - u64 chain_key = INITIAL_CHAIN_KEY; - - for (i = 0; i < curr->lockdep_depth; i++) { - hlock = curr->held_locks + i; - if (chain_key != hlock->prev_chain_key) { - debug_locks_off(); - /* - * We got mighty confused, our chain keys don't match - * with what we expect, someone trample on our task state? - */ - WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", - curr->lockdep_depth, i, - (unsigned long long)chain_key, - (unsigned long long)hlock->prev_chain_key); - return; - } - - /* - * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is - * it registered lock class index? - */ - if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use))) - return; - - if (prev_hlock && (prev_hlock->irq_context != - hlock->irq_context)) - chain_key = INITIAL_CHAIN_KEY; - chain_key = iterate_chain_key(chain_key, hlock->class_idx); - prev_hlock = hlock; - } - if (chain_key != curr->curr_chain_key) { - debug_locks_off(); - /* - * More smoking hash instead of calculating it, damn see these - * numbers float.. I bet that a pink elephant stepped on my memory. - */ - WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", - curr->lockdep_depth, i, - (unsigned long long)chain_key, - (unsigned long long)curr->curr_chain_key); - } -#endif -} - -#ifdef CONFIG_PROVE_LOCKING -static int mark_lock(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit); - -static void print_usage_bug_scenario(struct held_lock *lock) -{ - struct lock_class *class = hlock_class(lock); - - printk(" Possible unsafe locking scenario:\n\n"); - printk(" CPU0\n"); - printk(" ----\n"); - printk(" lock("); - __print_lock_name(class); - printk(KERN_CONT ");\n"); - printk(" \n"); - printk(" lock("); - __print_lock_name(class); - printk(KERN_CONT ");\n"); - printk("\n *** DEADLOCK ***\n\n"); -} - -static void -print_usage_bug(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) -{ - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return; - - pr_warn("\n"); - pr_warn("================================\n"); - pr_warn("WARNING: inconsistent lock state\n"); - print_kernel_ident(); - pr_warn("--------------------------------\n"); - - pr_warn("inconsistent {%s} -> {%s} usage.\n", - usage_str[prev_bit], usage_str[new_bit]); - - pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", - curr->comm, task_pid_nr(curr), - trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, - trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, - trace_hardirqs_enabled(curr), - trace_softirqs_enabled(curr)); - print_lock(this); - - pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]); - print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1); - - print_irqtrace_events(curr); - pr_warn("\nother info that might help us debug this:\n"); - print_usage_bug_scenario(this); - - lockdep_print_held_locks(curr); - - pr_warn("\nstack backtrace:\n"); - dump_stack(); -} - -/* - * Print out an error if an invalid bit is set: - */ -static inline int -valid_state(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) -{ - if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) { - print_usage_bug(curr, this, bad_bit, new_bit); - return 0; - } - return 1; -} - - -/* - * print irq inversion bug: - */ -static void -print_irq_inversion_bug(struct task_struct *curr, - struct lock_list *root, struct lock_list *other, - struct held_lock *this, int forwards, - const char *irqclass) -{ - struct lock_list *entry = other; - struct lock_list *middle = NULL; - int depth; - - if (!debug_locks_off_graph_unlock() || debug_locks_silent) - return; - - pr_warn("\n"); - pr_warn("========================================================\n"); - pr_warn("WARNING: possible irq lock inversion dependency detected\n"); - print_kernel_ident(); - pr_warn("--------------------------------------------------------\n"); - pr_warn("%s/%d just changed the state of lock:\n", - curr->comm, task_pid_nr(curr)); - print_lock(this); - if (forwards) - pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); - else - pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); - print_lock_name(other->class); - pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); - - pr_warn("\nother info that might help us debug this:\n"); - - /* Find a middle lock (if one exists) */ - depth = get_lock_depth(other); - do { - if (depth == 0 && (entry != root)) { - pr_warn("lockdep:%s bad path found in chain graph\n", __func__); - break; - } - middle = entry; - entry = get_lock_parent(entry); - depth--; - } while (entry && entry != root && (depth >= 0)); - if (forwards) - print_irq_lock_scenario(root, other, - middle ? middle->class : root->class, other->class); - else - print_irq_lock_scenario(other, root, - middle ? middle->class : other->class, root->class); - - lockdep_print_held_locks(curr); - - pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); - root->trace = save_trace(); - if (!root->trace) - return; - print_shortest_lock_dependencies(other, root); - - pr_warn("\nstack backtrace:\n"); - dump_stack(); -} - -/* - * Prove that in the forwards-direction subgraph starting at - * there is no lock matching : - */ -static int -check_usage_forwards(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit bit, const char *irqclass) -{ - int ret; - struct lock_list root; - struct lock_list *uninitialized_var(target_entry); - - root.parent = NULL; - root.class = hlock_class(this); - ret = find_usage_forwards(&root, lock_flag(bit), &target_entry); - if (ret < 0) { - print_bfs_bug(ret); - return 0; - } - if (ret == 1) - return ret; - - print_irq_inversion_bug(curr, &root, target_entry, - this, 1, irqclass); - return 0; -} - -/* - * Prove that in the backwards-direction subgraph starting at - * there is no lock matching : - */ -static int -check_usage_backwards(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit bit, const char *irqclass) -{ - int ret; - struct lock_list root; - struct lock_list *uninitialized_var(target_entry); - - root.parent = NULL; - root.class = hlock_class(this); - ret = find_usage_backwards(&root, lock_flag(bit), &target_entry); - if (ret < 0) { - print_bfs_bug(ret); - return 0; - } - if (ret == 1) - return ret; - - print_irq_inversion_bug(curr, &root, target_entry, - this, 0, irqclass); - return 0; -} - -void print_irqtrace_events(struct task_struct *curr) -{ - printk("irq event stamp: %u\n", curr->irq_events); - printk("hardirqs last enabled at (%u): [<%px>] %pS\n", - curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip, - (void *)curr->hardirq_enable_ip); - printk("hardirqs last disabled at (%u): [<%px>] %pS\n", - curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip, - (void *)curr->hardirq_disable_ip); - printk("softirqs last enabled at (%u): [<%px>] %pS\n", - curr->softirq_enable_event, (void *)curr->softirq_enable_ip, - (void *)curr->softirq_enable_ip); - printk("softirqs last disabled at (%u): [<%px>] %pS\n", - curr->softirq_disable_event, (void *)curr->softirq_disable_ip, - (void *)curr->softirq_disable_ip); -} - -static int HARDIRQ_verbose(struct lock_class *class) -{ -#if HARDIRQ_VERBOSE - return class_filter(class); -#endif - return 0; -} - -static int SOFTIRQ_verbose(struct lock_class *class) -{ -#if SOFTIRQ_VERBOSE - return class_filter(class); -#endif - return 0; -} - -#define STRICT_READ_CHECKS 1 - -static int (*state_verbose_f[])(struct lock_class *class) = { -#define LOCKDEP_STATE(__STATE) \ - __STATE##_verbose, -#include "lockdep_states.h" -#undef LOCKDEP_STATE -}; - -static inline int state_verbose(enum lock_usage_bit bit, - struct lock_class *class) -{ - return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class); -} - -typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, - enum lock_usage_bit bit, const char *name); - -static int -mark_lock_irq(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit) -{ - int excl_bit = exclusive_bit(new_bit); - int read = new_bit & LOCK_USAGE_READ_MASK; - int dir = new_bit & LOCK_USAGE_DIR_MASK; - - /* - * mark USED_IN has to look forwards -- to ensure no dependency - * has ENABLED state, which would allow recursion deadlocks. - * - * mark ENABLED has to look backwards -- to ensure no dependee - * has USED_IN state, which, again, would allow recursion deadlocks. - */ - check_usage_f usage = dir ? - check_usage_backwards : check_usage_forwards; - - /* - * Validate that this particular lock does not have conflicting - * usage states. - */ - if (!valid_state(curr, this, new_bit, excl_bit)) - return 0; - - /* - * Validate that the lock dependencies don't have conflicting usage - * states. - */ - if ((!read || STRICT_READ_CHECKS) && - !usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK))) - return 0; - - /* - * Check for read in write conflicts - */ - if (!read) { - if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK)) - return 0; - - if (STRICT_READ_CHECKS && - !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK, - state_name(new_bit + LOCK_USAGE_READ_MASK))) - return 0; - } - - if (state_verbose(new_bit, hlock_class(this))) - return 2; - - return 1; -} - -/* - * Mark all held locks with a usage bit: - */ -static int -mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit) -{ - struct held_lock *hlock; - int i; - - for (i = 0; i < curr->lockdep_depth; i++) { - enum lock_usage_bit hlock_bit = base_bit; - hlock = curr->held_locks + i; - - if (hlock->read) - hlock_bit += LOCK_USAGE_READ_MASK; - - BUG_ON(hlock_bit >= LOCK_USAGE_STATES); - - if (!hlock->check) - continue; - - if (!mark_lock(curr, hlock, hlock_bit)) - return 0; - } - - return 1; -} - -/* - * Hardirqs will be enabled: - */ -static void __trace_hardirqs_on_caller(unsigned long ip) -{ - struct task_struct *curr = current; - - /* we'll do an OFF -> ON transition: */ - curr->hardirqs_enabled = 1; - - /* - * We are going to turn hardirqs on, so set the - * usage bit for all held locks: - */ - if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ)) - return; - /* - * If we have softirqs enabled, then set the usage - * bit for all held locks. (disabled hardirqs prevented - * this bit from being set before) - */ - if (curr->softirqs_enabled) - if (!mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ)) - return; - - curr->hardirq_enable_ip = ip; - curr->hardirq_enable_event = ++curr->irq_events; - debug_atomic_inc(hardirqs_on_events); -} - -void lockdep_hardirqs_on(unsigned long ip) -{ - if (unlikely(!debug_locks || current->lockdep_recursion)) - return; - - if (unlikely(current->hardirqs_enabled)) { - /* - * Neither irq nor preemption are disabled here - * so this is racy by nature but losing one hit - * in a stat is not a big deal. - */ - __debug_atomic_inc(redundant_hardirqs_on); - return; - } - - /* - * We're enabling irqs and according to our state above irqs weren't - * already enabled, yet we find the hardware thinks they are in fact - * enabled.. someone messed up their IRQ state tracing. - */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - - /* - * See the fine text that goes along with this variable definition. - */ - if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)) - return; - - /* - * Can't allow enabling interrupts while in an interrupt handler, - * that's general bad form and such. Recursion, limited stack etc.. - */ - if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) - return; - - current->lockdep_recursion = 1; - __trace_hardirqs_on_caller(ip); - current->lockdep_recursion = 0; -} -NOKPROBE_SYMBOL(lockdep_hardirqs_on); - -/* - * Hardirqs were disabled: - */ -void lockdep_hardirqs_off(unsigned long ip) -{ - struct task_struct *curr = current; - - if (unlikely(!debug_locks || current->lockdep_recursion)) - return; - - /* - * So we're supposed to get called after you mask local IRQs, but for - * some reason the hardware doesn't quite think you did a proper job. - */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - - if (curr->hardirqs_enabled) { - /* - * We have done an ON -> OFF transition: - */ - curr->hardirqs_enabled = 0; - curr->hardirq_disable_ip = ip; - curr->hardirq_disable_event = ++curr->irq_events; - debug_atomic_inc(hardirqs_off_events); - } else - debug_atomic_inc(redundant_hardirqs_off); -} -NOKPROBE_SYMBOL(lockdep_hardirqs_off); - -/* - * Softirqs will be enabled: - */ -void trace_softirqs_on(unsigned long ip) -{ - struct task_struct *curr = current; - - if (unlikely(!debug_locks || current->lockdep_recursion)) - return; - - /* - * We fancy IRQs being disabled here, see softirq.c, avoids - * funny state and nesting things. - */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - - if (curr->softirqs_enabled) { - debug_atomic_inc(redundant_softirqs_on); - return; - } - - current->lockdep_recursion = 1; - /* - * We'll do an OFF -> ON transition: - */ - curr->softirqs_enabled = 1; - curr->softirq_enable_ip = ip; - curr->softirq_enable_event = ++curr->irq_events; - debug_atomic_inc(softirqs_on_events); - /* - * We are going to turn softirqs on, so set the - * usage bit for all held locks, if hardirqs are - * enabled too: - */ - if (curr->hardirqs_enabled) - mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ); - current->lockdep_recursion = 0; -} - -/* - * Softirqs were disabled: - */ -void trace_softirqs_off(unsigned long ip) -{ - struct task_struct *curr = current; - - if (unlikely(!debug_locks || current->lockdep_recursion)) - return; - - /* - * We fancy IRQs being disabled here, see softirq.c - */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) - return; - - if (curr->softirqs_enabled) { - /* - * We have done an ON -> OFF transition: - */ - curr->softirqs_enabled = 0; - curr->softirq_disable_ip = ip; - curr->softirq_disable_event = ++curr->irq_events; - debug_atomic_inc(softirqs_off_events); - /* - * Whoops, we wanted softirqs off, so why aren't they? - */ - DEBUG_LOCKS_WARN_ON(!softirq_count()); - } else - debug_atomic_inc(redundant_softirqs_off); -} - -static int -mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) -{ - if (!check) - goto lock_used; - - /* - * If non-trylock use in a hardirq or softirq context, then - * mark the lock as used in these contexts: - */ - if (!hlock->trylock) { - if (hlock->read) { - if (curr->hardirq_context) - if (!mark_lock(curr, hlock, - LOCK_USED_IN_HARDIRQ_READ)) - return 0; - if (curr->softirq_context) - if (!mark_lock(curr, hlock, - LOCK_USED_IN_SOFTIRQ_READ)) - return 0; - } else { - if (curr->hardirq_context) - if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) - return 0; - if (curr->softirq_context) - if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) - return 0; - } - } - if (!hlock->hardirqs_off) { - if (hlock->read) { - if (!mark_lock(curr, hlock, - LOCK_ENABLED_HARDIRQ_READ)) - return 0; - if (curr->softirqs_enabled) - if (!mark_lock(curr, hlock, - LOCK_ENABLED_SOFTIRQ_READ)) - return 0; - } else { - if (!mark_lock(curr, hlock, - LOCK_ENABLED_HARDIRQ)) - return 0; - if (curr->softirqs_enabled) - if (!mark_lock(curr, hlock, - LOCK_ENABLED_SOFTIRQ)) - return 0; - } + hlist_for_each_entry_rcu(k, hash_head, hash_entry) { + if (WARN_ON_ONCE(k == key)) + goto out_unlock; } - -lock_used: - /* mark it as used: */ - if (!mark_lock(curr, hlock, LOCK_USED)) - return 0; - - return 1; + hlist_add_head_rcu(&key->hash_entry, hash_head); +out_unlock: + graph_unlock(); +restore_irqs: + raw_local_irq_restore(flags); } +EXPORT_SYMBOL_GPL(lockdep_register_key); -static inline unsigned int task_irq_context(struct task_struct *task) +/* Check whether a key has been registered as a dynamic key. */ +static bool is_dynamic_key(const struct lock_class_key *key) { - return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context + - LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context; -} + struct hlist_head *hash_head; + struct lock_class_key *k; + bool found = false; -static int separate_irq_context(struct task_struct *curr, - struct held_lock *hlock) -{ - unsigned int depth = curr->lockdep_depth; + if (WARN_ON_ONCE(static_obj(key))) + return false; /* - * Keep track of points where we cross into an interrupt context: + * If lock debugging is disabled lock_keys_hash[] may contain + * pointers to memory that has already been freed. Avoid triggering + * a use-after-free in that case by returning early. */ - if (depth) { - struct held_lock *prev_hlock; + if (!debug_locks) + return true; - prev_hlock = curr->held_locks + depth-1; - /* - * If we cross into another context, reset the - * hash key (this also prevents the checking and the - * adding of the dependency to 'prev'): - */ - if (prev_hlock->irq_context != hlock->irq_context) - return 1; + hash_head = keyhashentry(key); + + rcu_read_lock(); + hlist_for_each_entry_rcu(k, hash_head, hash_entry) { + if (k == key) { + found = true; + break; + } } - return 0; + rcu_read_unlock(); + + return found; } /* - * Mark a lock with a usage bit, and validate the state transition: + * Register a lock's class in the hash-table, if the class is not present + * yet. Otherwise we look it up. We cache the result in the lock object + * itself, so actual lookup of the hash should be once per lock object. */ -static int mark_lock(struct task_struct *curr, struct held_lock *this, - enum lock_usage_bit new_bit) +static struct lock_class * +register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) { - unsigned int new_mask = 1 << new_bit, ret = 1; + struct lockdep_subclass_key *key; + struct hlist_head *hash_head; + struct lock_class *class; - if (new_bit >= LOCK_USAGE_STATES) { - DEBUG_LOCKS_WARN_ON(1); - return 0; + DEBUG_LOCKS_WARN_ON(!irqs_disabled()); + + class = look_up_lock_class(lock, subclass); + if (likely(class)) + goto out_set_class_cache; + + if (!lock->key) { + if (!assign_lock_key(lock)) + return NULL; + } else if (!static_obj(lock->key) && !is_dynamic_key(lock->key)) { + return NULL; } - /* - * If already set then do not dirty the cacheline, - * nor do any checks: - */ - if (likely(hlock_class(this)->usage_mask & new_mask)) - return 1; + key = lock->key->subkeys + subclass; + hash_head = classhashentry(key); - if (!graph_lock()) - return 0; + if (!graph_lock()) { + return NULL; + } /* - * Make sure we didn't race: + * We have to do the hash-walk again, to avoid races + * with another CPU: */ - if (unlikely(hlock_class(this)->usage_mask & new_mask)) { - graph_unlock(); - return 1; + hlist_for_each_entry_rcu(class, hash_head, hash_entry) { + if (class->key == key) + goto out_unlock_set; } - hlock_class(this)->usage_mask |= new_mask; + init_data_structures_once(); - if (!(hlock_class(this)->usage_traces[new_bit] = save_trace())) - return 0; + /* Allocate a new lock class and add it to the hash. */ + class = list_first_entry_or_null(&free_lock_classes, typeof(*class), + lock_entry); + if (!class) { + if (!debug_locks_off_graph_unlock()) { + return NULL; + } - switch (new_bit) { - case LOCK_USED: - debug_atomic_dec(nr_unused_locks); - break; - default: - ret = mark_lock_irq(curr, this, new_bit); - if (!ret) - return 0; + print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); + dump_stack(); + return NULL; } - - graph_unlock(); - + nr_lock_classes++; + __set_bit(class - lock_classes, lock_classes_in_use); + debug_atomic_inc(nr_unused_locks); + class->key = key; + class->name = lock->name; + class->subclass = subclass; + WARN_ON_ONCE(!list_empty(&class->locks_before)); + WARN_ON_ONCE(!list_empty(&class->locks_after)); + class->name_version = count_matching_names(class); + /* + * We use RCU's safe list-add method to make + * parallel walking of the hash-list safe: + */ + hlist_add_head_rcu(&class->hash_entry, hash_head); /* - * We must printk outside of the graph_lock: + * Remove the class from the free list and add it to the global list + * of classes. */ - if (ret == 2) { - printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); - print_lock(this); - print_irqtrace_events(curr); + list_move_tail(&class->lock_entry, &all_lock_classes); + + if (verbose(class)) { + graph_unlock(); + + printk("\nnew class %px: %s", class->key, class->name); + if (class->name_version > 1) + printk(KERN_CONT "#%d", class->name_version); + printk(KERN_CONT "\n"); dump_stack(); + + if (!graph_lock()) { + return NULL; + } } +out_unlock_set: + graph_unlock(); - return ret; -} +out_set_class_cache: + if (!subclass || force) + lock->class_cache[0] = class; + else if (subclass < NR_LOCKDEP_CACHING_CLASSES) + lock->class_cache[subclass] = class; -#else /* CONFIG_PROVE_LOCKING */ + /* + * Hash collision, did we smoke some? We found a class with a matching + * hash but the subclass -- which is hashed in -- didn't match. + */ + if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) + return NULL; -static inline int -mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) -{ - return 1; + return class; } -static inline unsigned int task_irq_context(struct task_struct *task) +/* + * We are building curr_chain_key incrementally, so double-check + * it from scratch, to make sure that it's done correctly: + */ +static void check_chain_key(struct task_struct *curr) { - return 0; -} +#ifdef CONFIG_DEBUG_LOCKDEP + struct held_lock *hlock, *prev_hlock = NULL; + unsigned int i; + u64 chain_key = INITIAL_CHAIN_KEY; -static inline int separate_irq_context(struct task_struct *curr, - struct held_lock *hlock) -{ - return 0; -} + for (i = 0; i < curr->lockdep_depth; i++) { + hlock = curr->held_locks + i; + if (chain_key != hlock->prev_chain_key) { + debug_locks_off(); + /* + * We got mighty confused, our chain keys don't match + * with what we expect, someone trample on our task state? + */ + WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", + curr->lockdep_depth, i, + (unsigned long long)chain_key, + (unsigned long long)hlock->prev_chain_key); + return; + } -#endif /* CONFIG_PROVE_LOCKING */ + /* + * hlock->class_idx can't go beyond MAX_LOCKDEP_KEYS, but is + * it registered lock class index? + */ + if (DEBUG_LOCKS_WARN_ON(!test_bit(hlock->class_idx, lock_classes_in_use))) + return; + + if (prev_hlock && (prev_hlock->irq_context != + hlock->irq_context)) + chain_key = INITIAL_CHAIN_KEY; + chain_key = iterate_chain_key(chain_key, hlock->class_idx); + prev_hlock = hlock; + } + if (chain_key != curr->curr_chain_key) { + debug_locks_off(); + /* + * More smoking hash instead of calculating it, damn see these + * numbers float.. I bet that a pink elephant stepped on my memory. + */ + WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", + curr->lockdep_depth, i, + (unsigned long long)chain_key, + (unsigned long long)curr->curr_chain_key); + } +#endif +} /* * Initialize a lock instance's lock-class mapping info: @@ -4624,45 +1911,6 @@ static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie WARN(1, "unpinning an unheld lock\n"); } -/* - * Check whether we follow the irq-flags state precisely: - */ -static void check_flags(unsigned long flags) -{ -#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) - if (!debug_locks) - return; - - if (irqs_disabled_flags(flags)) { - if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { - printk("possible reason: unannotated irqs-off.\n"); - } - } else { - if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { - printk("possible reason: unannotated irqs-on.\n"); - } - } - - /* - * We dont accurately track softirq state in e.g. - * hardirq contexts (such as on 4KSTACKS), so only - * check if not in hardirq contexts: - */ - if (!hardirq_count()) { - if (softirq_count()) { - /* like the above, but with softirqs */ - DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); - } else { - /* lick the above, does it taste good? */ - DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); - } - } - - if (!debug_locks) - print_irqtrace_events(current); -#endif -} - void lock_set_class(struct lockdep_map *lock, const char *name, struct lock_class_key *key, unsigned int subclass, unsigned long ip) @@ -4998,60 +2246,6 @@ void lockdep_reset(void) raw_local_irq_restore(flags); } -#ifdef CONFIG_PROVE_LOCKING -/* Remove a class from a lock chain. Must be called with the graph lock held. */ -static void remove_class_from_lock_chain(struct pending_free *pf, - struct lock_chain *chain, - struct lock_class *class) -{ - int i; - - for (i = chain->base; i < chain->base + chain->depth; i++) { - if (chain_hlocks[i] != class - lock_classes) - continue; - /* - * Each lock class occurs at most once in a lock chain so once - * we found a match we can break out of this loop. - */ - goto free_lock_chain; - } - /* Since the chain has not been modified, return. */ - return; - -free_lock_chain: - free_chain_hlocks(chain->base, chain->depth); - /* Overwrite the chain key for concurrent RCU readers. */ - WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY); - dec_chains(chain->irq_context); - - /* - * Note: calling hlist_del_rcu() from inside a - * hlist_for_each_entry_rcu() loop is safe. - */ - hlist_del_rcu(&chain->entry); - __set_bit(chain - lock_chains, pf->lock_chains_being_freed); - nr_zapped_lock_chains++; -} -#endif - -/* Must be called with the graph lock held. */ -static void remove_class_from_lock_chains(struct pending_free *pf, - struct lock_class *class) -{ -#ifdef CONFIG_PROVE_LOCKING - struct lock_chain *chain; - struct hlist_head *head; - int i; - - for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) { - head = chainhash_table + i; - hlist_for_each_entry_rcu(chain, head, entry) { - remove_class_from_lock_chain(pf, chain, class); - } - } -#endif -} - /* * Remove all references to a lock class. The caller must hold the graph lock. */ diff --git a/kernel/locking/lockdep_prove.c b/kernel/locking/lockdep_prove.c new file mode 100644 index 000000000000..e3709489f6ee --- /dev/null +++ b/kernel/locking/lockdep_prove.c @@ -0,0 +1,2820 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * This file is included in lockdep.c when CONFIG_PROVE_LOCKING is on. + * It contains all the functions and data structures that are needed to + * implement the CONFIG_PROVE_LOCKING functionality. + */ + +/** + * struct lock_trace - single stack backtrace + * @hash_entry: Entry in a stack_trace_hash[] list. + * @hash: jhash() of @entries. + * @nr_entries: Number of entries in @entries. + * @entries: Actual stack backtrace. + */ +struct lock_trace { + struct hlist_node hash_entry; + u32 hash; + u32 nr_entries; + unsigned long entries[0] __aligned(sizeof(unsigned long)); +}; +#define LOCK_TRACE_SIZE_IN_LONGS \ + (sizeof(struct lock_trace) / sizeof(unsigned long)) +/* + * Stack-trace: sequence of lock_trace structures. Protected by the graph_lock. + */ +static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; +static struct hlist_head stack_trace_hash[STACK_TRACE_HASH_SIZE]; + +struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; +static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS); +static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; +unsigned long nr_zapped_lock_chains; +unsigned int nr_free_chain_hlocks; /* Free chain_hlocks in buckets */ +unsigned int nr_lost_chain_hlocks; /* Lost chain_hlocks */ +unsigned int nr_large_chain_blocks; /* size > MAX_CHAIN_BUCKETS */ + +/* + * Forward references + */ +static void init_data_structures_once(void); +static int mark_lock(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit new_bit); + +/* + * Locking printouts: + */ + +#define __USAGE(__STATE) \ + [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ + [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ + [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ + [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", + +static const char *usage_str[] = +{ +#define LOCKDEP_STATE(__STATE) __USAGE(__STATE) +#include "lockdep_states.h" +#undef LOCKDEP_STATE + [LOCK_USED] = "INITIAL USE", +}; + +static bool traces_identical(struct lock_trace *t1, struct lock_trace *t2) +{ + return t1->hash == t2->hash && t1->nr_entries == t2->nr_entries && + memcmp(t1->entries, t2->entries, + t1->nr_entries * sizeof(t1->entries[0])) == 0; +} + +static struct lock_trace *save_trace(void) +{ + struct lock_trace *trace, *t2; + struct hlist_head *hash_head; + u32 hash; + int max_entries; + + BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE); + BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES); + + trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries); + max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries - + LOCK_TRACE_SIZE_IN_LONGS; + + if (max_entries <= 0) { + if (!debug_locks_off_graph_unlock()) + return NULL; + + print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); + dump_stack(); + + return NULL; + } + trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3); + + hash = jhash(trace->entries, trace->nr_entries * + sizeof(trace->entries[0]), 0); + trace->hash = hash; + hash_head = stack_trace_hash + (hash & (STACK_TRACE_HASH_SIZE - 1)); + hlist_for_each_entry(t2, hash_head, hash_entry) { + if (traces_identical(trace, t2)) + return t2; + } + nr_stack_trace_entries += LOCK_TRACE_SIZE_IN_LONGS + trace->nr_entries; + hlist_add_head(&trace->hash_entry, hash_head); + + return trace; +} + +/* Return the number of stack traces in the stack_trace[] array. */ +u64 lockdep_stack_trace_count(void) +{ + struct lock_trace *trace; + u64 c = 0; + int i; + + for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) { + hlist_for_each_entry(trace, &stack_trace_hash[i], hash_entry) { + c++; + } + } + + return c; +} + +/* Return the number of stack hash chains that have at least one stack trace. */ +u64 lockdep_stack_hash_count(void) +{ + u64 c = 0; + int i; + + for (i = 0; i < ARRAY_SIZE(stack_trace_hash); i++) + if (!hlist_empty(&stack_trace_hash[i])) + c++; + + return c; +} + +/* + * Allocate a lockdep entry. (assumes the graph_lock held, returns + * with NULL on failure) + */ +static struct lock_list *alloc_list_entry(void) +{ + int idx = find_first_zero_bit(list_entries_in_use, + ARRAY_SIZE(list_entries)); + + if (idx >= ARRAY_SIZE(list_entries)) { + if (!debug_locks_off_graph_unlock()) + return NULL; + + print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); + dump_stack(); + return NULL; + } + nr_list_entries++; + __set_bit(idx, list_entries_in_use); + return list_entries + idx; +} + +/* + * Add a new dependency to the head of the list: + */ +static int add_lock_to_list(struct lock_class *this, + struct lock_class *links_to, struct list_head *head, + unsigned long ip, int distance, + const struct lock_trace *trace) +{ + struct lock_list *entry; + /* + * Lock not present yet - get a new dependency struct and + * add it to the list: + */ + entry = alloc_list_entry(); + if (!entry) + return 0; + + entry->class = this; + entry->links_to = links_to; + entry->distance = distance; + entry->trace = trace; + /* + * Both allocation and removal are done under the graph lock; but + * iteration is under RCU-sched; see look_up_lock_class() and + * lockdep_free_key_range(). + */ + list_add_tail_rcu(&entry->entry, head); + + return 1; +} + +/* + * For good efficiency of modular, we use power of 2 + */ +#define MAX_CIRCULAR_QUEUE_SIZE 4096UL +#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) + +/* + * The circular_queue and helpers are used to implement graph + * breadth-first search (BFS) algorithm, by which we can determine + * whether there is a path from a lock to another. In deadlock checks, + * a path from the next lock to be acquired to a previous held lock + * indicates that adding the -> lock dependency will + * produce a circle in the graph. Breadth-first search instead of + * depth-first search is used in order to find the shortest (circular) + * path. + */ +struct circular_queue { + struct lock_list *element[MAX_CIRCULAR_QUEUE_SIZE]; + unsigned int front, rear; +}; + +static struct circular_queue lock_cq; + +unsigned int max_bfs_queue_depth; + +static unsigned int lockdep_dependency_gen_id; + +static inline void __cq_init(struct circular_queue *cq) +{ + cq->front = cq->rear = 0; + lockdep_dependency_gen_id++; +} + +static inline int __cq_empty(struct circular_queue *cq) +{ + return (cq->front == cq->rear); +} + +static inline int __cq_full(struct circular_queue *cq) +{ + return ((cq->rear + 1) & CQ_MASK) == cq->front; +} + +static inline int __cq_enqueue(struct circular_queue *cq, struct lock_list *elem) +{ + if (__cq_full(cq)) + return -1; + + cq->element[cq->rear] = elem; + cq->rear = (cq->rear + 1) & CQ_MASK; + return 0; +} + +/* + * Dequeue an element from the circular_queue, return a lock_list if + * the queue is not empty, or NULL if otherwise. + */ +static inline struct lock_list * __cq_dequeue(struct circular_queue *cq) +{ + struct lock_list * lock; + + if (__cq_empty(cq)) + return NULL; + + lock = cq->element[cq->front]; + cq->front = (cq->front + 1) & CQ_MASK; + + return lock; +} + +static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) +{ + return (cq->rear - cq->front) & CQ_MASK; +} + +static inline void mark_lock_accessed(struct lock_list *lock, + struct lock_list *parent) +{ + unsigned long nr; + + nr = lock - list_entries; + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ + lock->parent = parent; + lock->class->dep_gen_id = lockdep_dependency_gen_id; +} + +static inline unsigned long lock_accessed(struct lock_list *lock) +{ + unsigned long nr; + + nr = lock - list_entries; + WARN_ON(nr >= ARRAY_SIZE(list_entries)); /* Out-of-bounds, input fail */ + return lock->class->dep_gen_id == lockdep_dependency_gen_id; +} + +static inline struct lock_list *get_lock_parent(struct lock_list *child) +{ + return child->parent; +} + +static inline int get_lock_depth(struct lock_list *child) +{ + int depth = 0; + struct lock_list *parent; + + while ((parent = get_lock_parent(child))) { + child = parent; + depth++; + } + return depth; +} + +/* + * Return the forward or backward dependency list. + * + * @lock: the lock_list to get its class's dependency list + * @offset: the offset to struct lock_class to determine whether it is + * locks_after or locks_before + */ +static inline struct list_head *get_dep_list(struct lock_list *lock, int offset) +{ + void *lock_class = lock->class; + + return lock_class + offset; +} + +/* + * Forward- or backward-dependency search, used for both circular dependency + * checking and hardirq-unsafe/softirq-unsafe checking. + */ +static int __bfs(struct lock_list *source_entry, + void *data, + int (*match)(struct lock_list *entry, void *data), + struct lock_list **target_entry, + int offset) +{ + struct lock_list *entry; + struct lock_list *lock; + struct list_head *head; + struct circular_queue *cq = &lock_cq; + int ret = 1; + + if (match(source_entry, data)) { + *target_entry = source_entry; + ret = 0; + goto exit; + } + + head = get_dep_list(source_entry, offset); + if (list_empty(head)) + goto exit; + + __cq_init(cq); + __cq_enqueue(cq, source_entry); + + while ((lock = __cq_dequeue(cq))) { + + if (!lock->class) { + ret = -2; + goto exit; + } + + head = get_dep_list(lock, offset); + + DEBUG_LOCKS_WARN_ON(!irqs_disabled()); + + list_for_each_entry_rcu(entry, head, entry) { + if (!lock_accessed(entry)) { + unsigned int cq_depth; + mark_lock_accessed(entry, lock); + if (match(entry, data)) { + *target_entry = entry; + ret = 0; + goto exit; + } + + if (__cq_enqueue(cq, entry)) { + ret = -1; + goto exit; + } + cq_depth = __cq_get_elem_count(cq); + if (max_bfs_queue_depth < cq_depth) + max_bfs_queue_depth = cq_depth; + } + } + } +exit: + return ret; +} + +static inline int __bfs_forwards(struct lock_list *src_entry, + void *data, + int (*match)(struct lock_list *entry, void *data), + struct lock_list **target_entry) +{ + return __bfs(src_entry, data, match, target_entry, + offsetof(struct lock_class, locks_after)); + +} + +static inline int __bfs_backwards(struct lock_list *src_entry, + void *data, + int (*match)(struct lock_list *entry, void *data), + struct lock_list **target_entry) +{ + return __bfs(src_entry, data, match, target_entry, + offsetof(struct lock_class, locks_before)); + +} + +static void print_lock_trace(const struct lock_trace *trace, + unsigned int spaces) +{ + stack_trace_print(trace->entries, trace->nr_entries, spaces); +} + +/* + * Print a dependency chain entry (this is only done when a deadlock + * has been detected): + */ +static noinline void +print_circular_bug_entry(struct lock_list *target, int depth) +{ + if (debug_locks_silent) + return; + printk("\n-> #%u", depth); + print_lock_name(target->class); + printk(KERN_CONT ":\n"); + print_lock_trace(target->trace, 6); +} + +static void +print_circular_lock_scenario(struct held_lock *src, + struct held_lock *tgt, + struct lock_list *prt) +{ + struct lock_class *source = hlock_class(src); + struct lock_class *target = hlock_class(tgt); + struct lock_class *parent = prt->class; + + /* + * A direct locking problem where unsafe_class lock is taken + * directly by safe_class lock, then all we need to show + * is the deadlock scenario, as it is obvious that the + * unsafe lock is taken under the safe lock. + * + * But if there is a chain instead, where the safe lock takes + * an intermediate lock (middle_class) where this lock is + * not the same as the safe lock, then the lock chain is + * used to describe the problem. Otherwise we would need + * to show a different CPU case for each link in the chain + * from the safe_class lock to the unsafe_class lock. + */ + if (parent != source) { + printk("Chain exists of:\n "); + __print_lock_name(source); + printk(KERN_CONT " --> "); + __print_lock_name(parent); + printk(KERN_CONT " --> "); + __print_lock_name(target); + printk(KERN_CONT "\n\n"); + } + + printk(" Possible unsafe locking scenario:\n\n"); + printk(" CPU0 CPU1\n"); + printk(" ---- ----\n"); + printk(" lock("); + __print_lock_name(target); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(parent); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(target); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(source); + printk(KERN_CONT ");\n"); + printk("\n *** DEADLOCK ***\n\n"); +} + +/* + * When a circular dependency is detected, print the + * header first: + */ +static noinline void +print_circular_bug_header(struct lock_list *entry, unsigned int depth, + struct held_lock *check_src, + struct held_lock *check_tgt) +{ + struct task_struct *curr = current; + + if (debug_locks_silent) + return; + + pr_warn("\n"); + pr_warn("======================================================\n"); + pr_warn("WARNING: possible circular locking dependency detected\n"); + print_kernel_ident(); + pr_warn("------------------------------------------------------\n"); + pr_warn("%s/%d is trying to acquire lock:\n", + curr->comm, task_pid_nr(curr)); + print_lock(check_src); + + pr_warn("\nbut task is already holding lock:\n"); + + print_lock(check_tgt); + pr_warn("\nwhich lock already depends on the new lock.\n\n"); + pr_warn("\nthe existing dependency chain (in reverse order) is:\n"); + + print_circular_bug_entry(entry, depth); +} + +static inline int class_equal(struct lock_list *entry, void *data) +{ + return entry->class == data; +} + +static noinline void print_circular_bug(struct lock_list *this, + struct lock_list *target, + struct held_lock *check_src, + struct held_lock *check_tgt) +{ + struct task_struct *curr = current; + struct lock_list *parent; + struct lock_list *first_parent; + int depth; + + if (!debug_locks_off_graph_unlock() || debug_locks_silent) + return; + + this->trace = save_trace(); + if (!this->trace) + return; + + depth = get_lock_depth(target); + + print_circular_bug_header(target, depth, check_src, check_tgt); + + parent = get_lock_parent(target); + first_parent = parent; + + while (parent) { + print_circular_bug_entry(parent, --depth); + parent = get_lock_parent(parent); + } + + printk("\nother info that might help us debug this:\n\n"); + print_circular_lock_scenario(check_src, check_tgt, + first_parent); + + lockdep_print_held_locks(curr); + + printk("\nstack backtrace:\n"); + dump_stack(); +} + +static noinline void print_bfs_bug(int ret) +{ + if (!debug_locks_off_graph_unlock()) + return; + + /* + * Breadth-first-search failed, graph got corrupted? + */ + WARN(1, "lockdep bfs error:%d\n", ret); +} + +static int noop_count(struct lock_list *entry, void *data) +{ + (*(unsigned long *)data)++; + return 0; +} + +static unsigned long __lockdep_count_forward_deps(struct lock_list *this) +{ + unsigned long count = 0; + struct lock_list *uninitialized_var(target_entry); + + __bfs_forwards(this, (void *)&count, noop_count, &target_entry); + + return count; +} +unsigned long lockdep_count_forward_deps(struct lock_class *class) +{ + unsigned long ret, flags; + struct lock_list this; + + this.parent = NULL; + this.class = class; + + raw_local_irq_save(flags); + arch_spin_lock(&lockdep_lock); + ret = __lockdep_count_forward_deps(&this); + arch_spin_unlock(&lockdep_lock); + raw_local_irq_restore(flags); + + return ret; +} + +static unsigned long __lockdep_count_backward_deps(struct lock_list *this) +{ + unsigned long count = 0; + struct lock_list *uninitialized_var(target_entry); + + __bfs_backwards(this, (void *)&count, noop_count, &target_entry); + + return count; +} + +unsigned long lockdep_count_backward_deps(struct lock_class *class) +{ + unsigned long ret, flags; + struct lock_list this; + + this.parent = NULL; + this.class = class; + + raw_local_irq_save(flags); + arch_spin_lock(&lockdep_lock); + ret = __lockdep_count_backward_deps(&this); + arch_spin_unlock(&lockdep_lock); + raw_local_irq_restore(flags); + + return ret; +} + +/* + * Check that the dependency graph starting at can lead to + * or not. Print an error and return 0 if it does. + */ +static noinline int +check_path(struct lock_class *target, struct lock_list *src_entry, + struct lock_list **target_entry) +{ + int ret; + + ret = __bfs_forwards(src_entry, (void *)target, class_equal, + target_entry); + + if (unlikely(ret < 0)) + print_bfs_bug(ret); + + return ret; +} + +/* + * Prove that the dependency graph starting at can not + * lead to . If it can, there is a circle when adding + * -> dependency. + * + * Print an error and return 0 if it does. + */ +static noinline int +check_noncircular(struct held_lock *src, struct held_lock *target, + struct lock_trace **const trace) +{ + int ret; + struct lock_list *uninitialized_var(target_entry); + struct lock_list src_entry = { + .class = hlock_class(src), + .parent = NULL, + }; + + debug_atomic_inc(nr_cyclic_checks); + + ret = check_path(hlock_class(target), &src_entry, &target_entry); + + if (unlikely(!ret)) { + if (!*trace) { + /* + * If save_trace fails here, the printing might + * trigger a WARN but because of the !nr_entries it + * should not do bad things. + */ + *trace = save_trace(); + } + + print_circular_bug(&src_entry, target_entry, src, target); + } + + return ret; +} + +#ifdef CONFIG_LOCKDEP_SMALL +/* + * Check that the dependency graph starting at can lead to + * or not. If it can, -> dependency is already + * in the graph. + * + * Print an error and return 2 if it does or 1 if it does not. + */ +static noinline int +check_redundant(struct held_lock *src, struct held_lock *target) +{ + int ret; + struct lock_list *uninitialized_var(target_entry); + struct lock_list src_entry = { + .class = hlock_class(src), + .parent = NULL, + }; + + debug_atomic_inc(nr_redundant_checks); + + ret = check_path(hlock_class(target), &src_entry, &target_entry); + + if (!ret) { + debug_atomic_inc(nr_redundant); + ret = 2; + } else if (ret < 0) + ret = 0; + + return ret; +} +#endif + +#ifdef CONFIG_TRACE_IRQFLAGS + +static inline int usage_accumulate(struct lock_list *entry, void *mask) +{ + *(unsigned long *)mask |= entry->class->usage_mask; + + return 0; +} + +/* + * Forwards and backwards subgraph searching, for the purposes of + * proving that two subgraphs can be connected by a new dependency + * without creating any illegal irq-safe -> irq-unsafe lock dependency. + */ + +static inline int usage_match(struct lock_list *entry, void *mask) +{ + return entry->class->usage_mask & *(unsigned long *)mask; +} + +/* + * Find a node in the forwards-direction dependency sub-graph starting + * at @root->class that matches @bit. + * + * Return 0 if such a node exists in the subgraph, and put that node + * into *@target_entry. + * + * Return 1 otherwise and keep *@target_entry unchanged. + * Return <0 on error. + */ +static int +find_usage_forwards(struct lock_list *root, unsigned long usage_mask, + struct lock_list **target_entry) +{ + int result; + + debug_atomic_inc(nr_find_usage_forwards_checks); + + result = __bfs_forwards(root, &usage_mask, usage_match, target_entry); + + return result; +} + +/* + * Find a node in the backwards-direction dependency sub-graph starting + * at @root->class that matches @bit. + * + * Return 0 if such a node exists in the subgraph, and put that node + * into *@target_entry. + * + * Return 1 otherwise and keep *@target_entry unchanged. + * Return <0 on error. + */ +static int +find_usage_backwards(struct lock_list *root, unsigned long usage_mask, + struct lock_list **target_entry) +{ + int result; + + debug_atomic_inc(nr_find_usage_backwards_checks); + + result = __bfs_backwards(root, &usage_mask, usage_match, target_entry); + + return result; +} + +static void print_lock_class_header(struct lock_class *class, int depth) +{ + int bit; + + printk("%*s->", depth, ""); + print_lock_name(class); +#ifdef CONFIG_DEBUG_LOCKDEP + printk(KERN_CONT " ops: %lu", debug_class_ops_read(class)); +#endif + printk(KERN_CONT " {\n"); + + for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { + if (class->usage_mask & (1 << bit)) { + int len = depth; + + len += printk("%*s %s", depth, "", usage_str[bit]); + len += printk(KERN_CONT " at:\n"); + print_lock_trace(class->usage_traces[bit], len); + } + } + printk("%*s }\n", depth, ""); + + printk("%*s ... key at: [<%px>] %pS\n", + depth, "", class->key, class->key); +} + +/* + * printk the shortest lock dependencies from @start to @end in reverse order: + */ +static void __used +print_shortest_lock_dependencies(struct lock_list *leaf, + struct lock_list *root) +{ + struct lock_list *entry = leaf; + int depth; + + /*compute depth from generated tree by BFS*/ + depth = get_lock_depth(leaf); + + do { + print_lock_class_header(entry->class, depth); + printk("%*s ... acquired at:\n", depth, ""); + print_lock_trace(entry->trace, 2); + printk("\n"); + + if (depth == 0 && (entry != root)) { + printk("lockdep:%s bad path found in chain graph\n", __func__); + break; + } + + entry = get_lock_parent(entry); + depth--; + } while (entry && (depth >= 0)); +} + +static void +print_irq_lock_scenario(struct lock_list *safe_entry, + struct lock_list *unsafe_entry, + struct lock_class *prev_class, + struct lock_class *next_class) +{ + struct lock_class *safe_class = safe_entry->class; + struct lock_class *unsafe_class = unsafe_entry->class; + struct lock_class *middle_class = prev_class; + + if (middle_class == safe_class) + middle_class = next_class; + + /* + * A direct locking problem where unsafe_class lock is taken + * directly by safe_class lock, then all we need to show + * is the deadlock scenario, as it is obvious that the + * unsafe lock is taken under the safe lock. + * + * But if there is a chain instead, where the safe lock takes + * an intermediate lock (middle_class) where this lock is + * not the same as the safe lock, then the lock chain is + * used to describe the problem. Otherwise we would need + * to show a different CPU case for each link in the chain + * from the safe_class lock to the unsafe_class lock. + */ + if (middle_class != unsafe_class) { + printk("Chain exists of:\n "); + __print_lock_name(safe_class); + printk(KERN_CONT " --> "); + __print_lock_name(middle_class); + printk(KERN_CONT " --> "); + __print_lock_name(unsafe_class); + printk(KERN_CONT "\n\n"); + } + + printk(" Possible interrupt unsafe locking scenario:\n\n"); + printk(" CPU0 CPU1\n"); + printk(" ---- ----\n"); + printk(" lock("); + __print_lock_name(unsafe_class); + printk(KERN_CONT ");\n"); + printk(" local_irq_disable();\n"); + printk(" lock("); + __print_lock_name(safe_class); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(middle_class); + printk(KERN_CONT ");\n"); + printk(" \n"); + printk(" lock("); + __print_lock_name(safe_class); + printk(KERN_CONT ");\n"); + printk("\n *** DEADLOCK ***\n\n"); +} + +static void +print_bad_irq_dependency(struct task_struct *curr, + struct lock_list *prev_root, + struct lock_list *next_root, + struct lock_list *backwards_entry, + struct lock_list *forwards_entry, + struct held_lock *prev, + struct held_lock *next, + enum lock_usage_bit bit1, + enum lock_usage_bit bit2, + const char *irqclass) +{ + if (!debug_locks_off_graph_unlock() || debug_locks_silent) + return; + + pr_warn("\n"); + pr_warn("=====================================================\n"); + pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", + irqclass, irqclass); + print_kernel_ident(); + pr_warn("-----------------------------------------------------\n"); + pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", + curr->comm, task_pid_nr(curr), + curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, + curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, + curr->hardirqs_enabled, + curr->softirqs_enabled); + print_lock(next); + + pr_warn("\nand this task is already holding:\n"); + print_lock(prev); + pr_warn("which would create a new lock dependency:\n"); + print_lock_name(hlock_class(prev)); + pr_cont(" ->"); + print_lock_name(hlock_class(next)); + pr_cont("\n"); + + pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", + irqclass); + print_lock_name(backwards_entry->class); + pr_warn("\n... which became %s-irq-safe at:\n", irqclass); + + print_lock_trace(backwards_entry->class->usage_traces[bit1], 1); + + pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); + print_lock_name(forwards_entry->class); + pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); + pr_warn("..."); + + print_lock_trace(forwards_entry->class->usage_traces[bit2], 1); + + pr_warn("\nother info that might help us debug this:\n\n"); + print_irq_lock_scenario(backwards_entry, forwards_entry, + hlock_class(prev), hlock_class(next)); + + lockdep_print_held_locks(curr); + + pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); + prev_root->trace = save_trace(); + if (!prev_root->trace) + return; + print_shortest_lock_dependencies(backwards_entry, prev_root); + + pr_warn("\nthe dependencies between the lock to be acquired"); + pr_warn(" and %s-irq-unsafe lock:\n", irqclass); + next_root->trace = save_trace(); + if (!next_root->trace) + return; + print_shortest_lock_dependencies(forwards_entry, next_root); + + pr_warn("\nstack backtrace:\n"); + dump_stack(); +} + +static const char *state_names[] = { +#define LOCKDEP_STATE(__STATE) \ + __stringify(__STATE), +#include "lockdep_states.h" +#undef LOCKDEP_STATE +}; + +static const char *state_rnames[] = { +#define LOCKDEP_STATE(__STATE) \ + __stringify(__STATE)"-READ", +#include "lockdep_states.h" +#undef LOCKDEP_STATE +}; + +static inline const char *state_name(enum lock_usage_bit bit) +{ + if (bit & LOCK_USAGE_READ_MASK) + return state_rnames[bit >> LOCK_USAGE_DIR_MASK]; + else + return state_names[bit >> LOCK_USAGE_DIR_MASK]; +} + +/* + * The bit number is encoded like: + * + * bit0: 0 exclusive, 1 read lock + * bit1: 0 used in irq, 1 irq enabled + * bit2-n: state + */ +static int exclusive_bit(int new_bit) +{ + int state = new_bit & LOCK_USAGE_STATE_MASK; + int dir = new_bit & LOCK_USAGE_DIR_MASK; + + /* + * keep state, bit flip the direction and strip read. + */ + return state | (dir ^ LOCK_USAGE_DIR_MASK); +} + +/* + * Observe that when given a bitmask where each bitnr is encoded as above, a + * right shift of the mask transforms the individual bitnrs as -1 and + * conversely, a left shift transforms into +1 for the individual bitnrs. + * + * So for all bits whose number have LOCK_ENABLED_* set (bitnr1 == 1), we can + * create the mask with those bit numbers using LOCK_USED_IN_* (bitnr1 == 0) + * instead by subtracting the bit number by 2, or shifting the mask right by 2. + * + * Similarly, bitnr1 == 0 becomes bitnr1 == 1 by adding 2, or shifting left 2. + * + * So split the mask (note that LOCKF_ENABLED_IRQ_ALL|LOCKF_USED_IN_IRQ_ALL is + * all bits set) and recompose with bitnr1 flipped. + */ +static unsigned long invert_dir_mask(unsigned long mask) +{ + unsigned long excl = 0; + + /* Invert dir */ + excl |= (mask & LOCKF_ENABLED_IRQ_ALL) >> LOCK_USAGE_DIR_MASK; + excl |= (mask & LOCKF_USED_IN_IRQ_ALL) << LOCK_USAGE_DIR_MASK; + + return excl; +} + +/* + * As above, we clear bitnr0 (LOCK_*_READ off) with bitmask ops. First, for all + * bits with bitnr0 set (LOCK_*_READ), add those with bitnr0 cleared (LOCK_*). + * And then mask out all bitnr0. + */ +static unsigned long exclusive_mask(unsigned long mask) +{ + unsigned long excl = invert_dir_mask(mask); + + /* Strip read */ + excl |= (excl & LOCKF_IRQ_READ) >> LOCK_USAGE_READ_MASK; + excl &= ~LOCKF_IRQ_READ; + + return excl; +} + +/* + * Retrieve the _possible_ original mask to which @mask is + * exclusive. Ie: this is the opposite of exclusive_mask(). + * Note that 2 possible original bits can match an exclusive + * bit: one has LOCK_USAGE_READ_MASK set, the other has it + * cleared. So both are returned for each exclusive bit. + */ +static unsigned long original_mask(unsigned long mask) +{ + unsigned long excl = invert_dir_mask(mask); + + /* Include read in existing usages */ + excl |= (excl & LOCKF_IRQ) << LOCK_USAGE_READ_MASK; + + return excl; +} + +/* + * Find the first pair of bit match between an original + * usage mask and an exclusive usage mask. + */ +static int find_exclusive_match(unsigned long mask, + unsigned long excl_mask, + enum lock_usage_bit *bitp, + enum lock_usage_bit *excl_bitp) +{ + int bit, excl; + + for_each_set_bit(bit, &mask, LOCK_USED) { + excl = exclusive_bit(bit); + if (excl_mask & lock_flag(excl)) { + *bitp = bit; + *excl_bitp = excl; + return 0; + } + } + return -1; +} + +/* + * Prove that the new dependency does not connect a hardirq-safe(-read) + * lock with a hardirq-unsafe lock - to achieve this we search + * the backwards-subgraph starting at , and the + * forwards-subgraph starting at : + */ +static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, + struct held_lock *next) +{ + unsigned long usage_mask = 0, forward_mask, backward_mask; + enum lock_usage_bit forward_bit = 0, backward_bit = 0; + struct lock_list *uninitialized_var(target_entry1); + struct lock_list *uninitialized_var(target_entry); + struct lock_list this, that; + int ret; + + /* + * Step 1: gather all hard/soft IRQs usages backward in an + * accumulated usage mask. + */ + this.parent = NULL; + this.class = hlock_class(prev); + + ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, NULL); + if (ret < 0) { + print_bfs_bug(ret); + return 0; + } + + usage_mask &= LOCKF_USED_IN_IRQ_ALL; + if (!usage_mask) + return 1; + + /* + * Step 2: find exclusive uses forward that match the previous + * backward accumulated mask. + */ + forward_mask = exclusive_mask(usage_mask); + + that.parent = NULL; + that.class = hlock_class(next); + + ret = find_usage_forwards(&that, forward_mask, &target_entry1); + if (ret < 0) { + print_bfs_bug(ret); + return 0; + } + if (ret == 1) + return ret; + + /* + * Step 3: we found a bad match! Now retrieve a lock from the backward + * list whose usage mask matches the exclusive usage mask from the + * lock found on the forward list. + */ + backward_mask = original_mask(target_entry1->class->usage_mask); + + ret = find_usage_backwards(&this, backward_mask, &target_entry); + if (ret < 0) { + print_bfs_bug(ret); + return 0; + } + if (DEBUG_LOCKS_WARN_ON(ret == 1)) + return 1; + + /* + * Step 4: narrow down to a pair of incompatible usage bits + * and report it. + */ + ret = find_exclusive_match(target_entry->class->usage_mask, + target_entry1->class->usage_mask, + &backward_bit, &forward_bit); + if (DEBUG_LOCKS_WARN_ON(ret == -1)) + return 1; + + print_bad_irq_dependency(curr, &this, &that, + target_entry, target_entry1, + prev, next, + backward_bit, forward_bit, + state_name(backward_bit)); + + return 0; +} + +#else + +static inline int check_irq_usage(struct task_struct *curr, + struct held_lock *prev, struct held_lock *next) +{ + return 1; +} +#endif /* CONFIG_TRACE_IRQFLAGS */ + +static void inc_chains(int irq_context) +{ + if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) + nr_hardirq_chains++; + else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) + nr_softirq_chains++; + else + nr_process_chains++; +} + +static void dec_chains(int irq_context) +{ + if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT) + nr_hardirq_chains--; + else if (irq_context & LOCK_CHAIN_SOFTIRQ_CONTEXT) + nr_softirq_chains--; + else + nr_process_chains--; +} + +static void +print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv) +{ + struct lock_class *next = hlock_class(nxt); + struct lock_class *prev = hlock_class(prv); + + printk(" Possible unsafe locking scenario:\n\n"); + printk(" CPU0\n"); + printk(" ----\n"); + printk(" lock("); + __print_lock_name(prev); + printk(KERN_CONT ");\n"); + printk(" lock("); + __print_lock_name(next); + printk(KERN_CONT ");\n"); + printk("\n *** DEADLOCK ***\n\n"); + printk(" May be due to missing lock nesting notation\n\n"); +} + +static void +print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, + struct held_lock *next) +{ + if (!debug_locks_off_graph_unlock() || debug_locks_silent) + return; + + pr_warn("\n"); + pr_warn("============================================\n"); + pr_warn("WARNING: possible recursive locking detected\n"); + print_kernel_ident(); + pr_warn("--------------------------------------------\n"); + pr_warn("%s/%d is trying to acquire lock:\n", + curr->comm, task_pid_nr(curr)); + print_lock(next); + pr_warn("\nbut task is already holding lock:\n"); + print_lock(prev); + + pr_warn("\nother info that might help us debug this:\n"); + print_deadlock_scenario(next, prev); + lockdep_print_held_locks(curr); + + pr_warn("\nstack backtrace:\n"); + dump_stack(); +} + +/* + * Check whether we are holding such a class already. + * + * (Note that this has to be done separately, because the graph cannot + * detect such classes of deadlocks.) + * + * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read + */ +static int +check_deadlock(struct task_struct *curr, struct held_lock *next) +{ + struct held_lock *prev; + struct held_lock *nest = NULL; + int i; + + for (i = 0; i < curr->lockdep_depth; i++) { + prev = curr->held_locks + i; + + if (prev->instance == next->nest_lock) + nest = prev; + + if (hlock_class(prev) != hlock_class(next)) + continue; + + /* + * Allow read-after-read recursion of the same + * lock class (i.e. read_lock(lock)+read_lock(lock)): + */ + if ((next->read == 2) && prev->read) + return 2; + + /* + * We're holding the nest_lock, which serializes this lock's + * nesting behaviour. + */ + if (nest) + return 2; + + print_deadlock_bug(curr, prev, next); + return 0; + } + return 1; +} + +/* + * There was a chain-cache miss, and we are about to add a new dependency + * to a previous lock. We validate the following rules: + * + * - would the adding of the -> dependency create a + * circular dependency in the graph? [== circular deadlock] + * + * - does the new prev->next dependency connect any hardirq-safe lock + * (in the full backwards-subgraph starting at ) with any + * hardirq-unsafe lock (in the full forwards-subgraph starting at + * )? [== illegal lock inversion with hardirq contexts] + * + * - does the new prev->next dependency connect any softirq-safe lock + * (in the full backwards-subgraph starting at ) with any + * softirq-unsafe lock (in the full forwards-subgraph starting at + * )? [== illegal lock inversion with softirq contexts] + * + * any of these scenarios could lead to a deadlock. + * + * Then if all the validations pass, we add the forwards and backwards + * dependency. + */ +static int +check_prev_add(struct task_struct *curr, struct held_lock *prev, + struct held_lock *next, int distance, + struct lock_trace **const trace) +{ + struct lock_list *entry; + int ret; + + if (!hlock_class(prev)->key || !hlock_class(next)->key) { + /* + * The warning statements below may trigger a use-after-free + * of the class name. It is better to trigger a use-after free + * and to have the class name most of the time instead of not + * having the class name available. + */ + WARN_ONCE(!debug_locks_silent && !hlock_class(prev)->key, + "Detected use-after-free of lock class %px/%s\n", + hlock_class(prev), + hlock_class(prev)->name); + WARN_ONCE(!debug_locks_silent && !hlock_class(next)->key, + "Detected use-after-free of lock class %px/%s\n", + hlock_class(next), + hlock_class(next)->name); + return 2; + } + + /* + * Prove that the new -> dependency would not + * create a circular dependency in the graph. (We do this by + * a breadth-first search into the graph starting at , + * and check whether we can reach .) + * + * The search is limited by the size of the circular queue (i.e., + * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes + * in the graph whose neighbours are to be checked. + */ + ret = check_noncircular(next, prev, trace); + if (unlikely(ret <= 0)) + return 0; + + if (!check_irq_usage(curr, prev, next)) + return 0; + + /* + * For recursive read-locks we do all the dependency checks, + * but we dont store read-triggered dependencies (only + * write-triggered dependencies). This ensures that only the + * write-side dependencies matter, and that if for example a + * write-lock never takes any other locks, then the reads are + * equivalent to a NOP. + */ + if (next->read == 2 || prev->read == 2) + return 1; + /* + * Is the -> dependency already present? + * + * (this may occur even though this is a new chain: consider + * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 + * chains - the second one will be new, but L1 already has + * L2 added to its dependency list, due to the first chain.) + */ + list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { + if (entry->class == hlock_class(next)) { + if (distance == 1) + entry->distance = 1; + return 1; + } + } + +#ifdef CONFIG_LOCKDEP_SMALL + /* + * Is the -> link redundant? + */ + ret = check_redundant(prev, next); + if (ret != 1) + return ret; +#endif + + if (!*trace) { + *trace = save_trace(); + if (!*trace) + return 0; + } + + /* + * Ok, all validations passed, add the new lock + * to the previous lock's dependency list: + */ + ret = add_lock_to_list(hlock_class(next), hlock_class(prev), + &hlock_class(prev)->locks_after, + next->acquire_ip, distance, *trace); + + if (!ret) + return 0; + + ret = add_lock_to_list(hlock_class(prev), hlock_class(next), + &hlock_class(next)->locks_before, + next->acquire_ip, distance, *trace); + if (!ret) + return 0; + + return 2; +} + +/* + * Add the dependency to all directly-previous locks that are 'relevant'. + * The ones that are relevant are (in increasing distance from curr): + * all consecutive trylock entries and the final non-trylock entry - or + * the end of this context's lock-chain - whichever comes first. + */ +static int +check_prevs_add(struct task_struct *curr, struct held_lock *next) +{ + struct lock_trace *trace = NULL; + int depth = curr->lockdep_depth; + struct held_lock *hlock; + + /* + * Debugging checks. + * + * Depth must not be zero for a non-head lock: + */ + if (!depth) + goto out_bug; + /* + * At least two relevant locks must exist for this + * to be a head: + */ + if (curr->held_locks[depth].irq_context != + curr->held_locks[depth-1].irq_context) + goto out_bug; + + for (;;) { + int distance = curr->lockdep_depth - depth + 1; + hlock = curr->held_locks + depth - 1; + + /* + * Only non-recursive-read entries get new dependencies + * added: + */ + if (hlock->read != 2 && hlock->check) { + int ret = check_prev_add(curr, hlock, next, distance, + &trace); + if (!ret) + return 0; + + /* + * Stop after the first non-trylock entry, + * as non-trylock entries have added their + * own direct dependencies already, so this + * lock is connected to them indirectly: + */ + if (!hlock->trylock) + break; + } + + depth--; + /* + * End of lock-stack? + */ + if (!depth) + break; + /* + * Stop the search if we cross into another context: + */ + if (curr->held_locks[depth].irq_context != + curr->held_locks[depth-1].irq_context) + break; + } + return 1; +out_bug: + if (!debug_locks_off_graph_unlock()) + return 0; + + /* + * Clearly we all shouldn't be here, but since we made it we + * can reliable say we messed up our state. See the above two + * gotos for reasons why we could possibly end up here. + */ + WARN_ON(1); + + return 0; +} + +/* + * The first 2 chain_hlocks entries in the chain block in the bucket + * list contains the following meta data: + * + * entry[0]: + * Bit 15 - always set to 1 (it is not a class index) + * Bits 0-14 - upper 15 bits of the next block index + * entry[1] - lower 16 bits of next block index + * + * A next block index of all 1 bits means it is the end of the list. + * + * On the unsized bucket (bucket-0), the 3rd and 4th entries contain + * the chain block size: + * + * entry[2] - upper 16 bits of the chain block size + * entry[3] - lower 16 bits of the chain block size + */ +#define MAX_CHAIN_BUCKETS 16 +#define CHAIN_BLK_FLAG (1U << 15) +#define CHAIN_BLK_LIST_END 0xFFFFU + +static int chain_block_buckets[MAX_CHAIN_BUCKETS]; + +static inline int size_to_bucket(int size) +{ + if (size > MAX_CHAIN_BUCKETS) + return 0; + + return size - 1; +} + +/* + * Iterate all the chain blocks in a bucket. + */ +#define for_each_chain_block(bucket, prev, curr) \ + for ((prev) = -1, (curr) = chain_block_buckets[bucket]; \ + (curr) >= 0; \ + (prev) = (curr), (curr) = chain_block_next(curr)) + +/* + * next block or -1 + */ +static inline int chain_block_next(int offset) +{ + int next = chain_hlocks[offset]; + + WARN_ON_ONCE(!(next & CHAIN_BLK_FLAG)); + + if (next == CHAIN_BLK_LIST_END) + return -1; + + next &= ~CHAIN_BLK_FLAG; + next <<= 16; + next |= chain_hlocks[offset + 1]; + + return next; +} + +/* + * bucket-0 only + */ +static inline int chain_block_size(int offset) +{ + return (chain_hlocks[offset + 2] << 16) | chain_hlocks[offset + 3]; +} + +static inline void init_chain_block(int offset, int next, int bucket, int size) +{ + chain_hlocks[offset] = (next >> 16) | CHAIN_BLK_FLAG; + chain_hlocks[offset + 1] = (u16)next; + + if (size && !bucket) { + chain_hlocks[offset + 2] = size >> 16; + chain_hlocks[offset + 3] = (u16)size; + } +} + +static inline void add_chain_block(int offset, int size) +{ + int bucket = size_to_bucket(size); + int next = chain_block_buckets[bucket]; + int prev, curr; + + if (unlikely(size < 2)) { + /* + * We can't store single entries on the freelist. Leak them. + * + * One possible way out would be to uniquely mark them, other + * than with CHAIN_BLK_FLAG, such that we can recover them when + * the block before it is re-added. + */ + if (size) + nr_lost_chain_hlocks++; + return; + } + + nr_free_chain_hlocks += size; + if (!bucket) { + nr_large_chain_blocks++; + + /* + * Variable sized, sort large to small. + */ + for_each_chain_block(0, prev, curr) { + if (size >= chain_block_size(curr)) + break; + } + init_chain_block(offset, curr, 0, size); + if (prev < 0) + chain_block_buckets[0] = offset; + else + init_chain_block(prev, offset, 0, 0); + return; + } + /* + * Fixed size, add to head. + */ + init_chain_block(offset, next, bucket, size); + chain_block_buckets[bucket] = offset; +} + +/* + * Only the first block in the list can be deleted. + * + * For the variable size bucket[0], the first block (the largest one) is + * returned, broken up and put back into the pool. So if a chain block of + * length > MAX_CHAIN_BUCKETS is ever used and zapped, it will just be + * queued up after the primordial chain block and never be used until the + * hlock entries in the primordial chain block is almost used up. That + * causes fragmentation and reduce allocation efficiency. That can be + * monitored by looking at the "large chain blocks" number in lockdep_stats. + */ +static inline void del_chain_block(int bucket, int size, int next) +{ + nr_free_chain_hlocks -= size; + chain_block_buckets[bucket] = next; + + if (!bucket) + nr_large_chain_blocks--; +} + +static void init_chain_block_buckets(void) +{ + int i; + + for (i = 0; i < MAX_CHAIN_BUCKETS; i++) + chain_block_buckets[i] = -1; + + add_chain_block(0, ARRAY_SIZE(chain_hlocks)); +} + +/* + * Return offset of a chain block of the right size or -1 if not found. + * + * Fairly simple worst-fit allocator with the addition of a number of size + * specific free lists. + */ +static int alloc_chain_hlocks(int req) +{ + int bucket, curr, size; + + /* + * We rely on the MSB to act as an escape bit to denote freelist + * pointers. Make sure this bit isn't set in 'normal' class_idx usage. + */ + BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG); + + init_data_structures_once(); + + if (nr_free_chain_hlocks < req) + return -1; + + /* + * We require a minimum of 2 (u16) entries to encode a freelist + * 'pointer'. + */ + req = max(req, 2); + bucket = size_to_bucket(req); + curr = chain_block_buckets[bucket]; + + if (bucket) { + if (curr >= 0) { + del_chain_block(bucket, req, chain_block_next(curr)); + return curr; + } + /* Try bucket 0 */ + curr = chain_block_buckets[0]; + } + + /* + * The variable sized freelist is sorted by size; the first entry is + * the largest. Use it if it fits. + */ + if (curr >= 0) { + size = chain_block_size(curr); + if (likely(size >= req)) { + del_chain_block(0, size, chain_block_next(curr)); + add_chain_block(curr + req, size - req); + return curr; + } + } + + /* + * Last resort, split a block in a larger sized bucket. + */ + for (size = MAX_CHAIN_BUCKETS; size > req; size--) { + bucket = size_to_bucket(size); + curr = chain_block_buckets[bucket]; + if (curr < 0) + continue; + + del_chain_block(bucket, size, chain_block_next(curr)); + add_chain_block(curr + req, size - req); + return curr; + } + + return -1; +} + +static inline void free_chain_hlocks(int base, int size) +{ + add_chain_block(base, max(size, 2)); +} + +struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) +{ + return lock_classes + chain_hlocks[chain->base + i]; +} + +/* + * Returns the index of the first held_lock of the current chain + */ +static inline int get_first_held_lock(struct task_struct *curr, + struct held_lock *hlock) +{ + int i; + struct held_lock *hlock_curr; + + for (i = curr->lockdep_depth - 1; i >= 0; i--) { + hlock_curr = curr->held_locks + i; + if (hlock_curr->irq_context != hlock->irq_context) + break; + + } + + return ++i; +} + +#ifdef CONFIG_DEBUG_LOCKDEP +/* + * Returns the next chain_key iteration + */ +static u64 print_chain_key_iteration(int class_idx, u64 chain_key) +{ + u64 new_chain_key = iterate_chain_key(chain_key, class_idx); + + printk(" class_idx:%d -> chain_key:%016Lx", + class_idx, + (unsigned long long)new_chain_key); + return new_chain_key; +} + +static void +print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) +{ + struct held_lock *hlock; + u64 chain_key = INITIAL_CHAIN_KEY; + int depth = curr->lockdep_depth; + int i = get_first_held_lock(curr, hlock_next); + + printk("depth: %u (irq_context %u)\n", depth - i + 1, + hlock_next->irq_context); + for (; i < depth; i++) { + hlock = curr->held_locks + i; + chain_key = print_chain_key_iteration(hlock->class_idx, chain_key); + + print_lock(hlock); + } + + print_chain_key_iteration(hlock_next->class_idx, chain_key); + print_lock(hlock_next); +} + +static void print_chain_keys_chain(struct lock_chain *chain) +{ + int i; + u64 chain_key = INITIAL_CHAIN_KEY; + int class_id; + + printk("depth: %u\n", chain->depth); + for (i = 0; i < chain->depth; i++) { + class_id = chain_hlocks[chain->base + i]; + chain_key = print_chain_key_iteration(class_id, chain_key); + + print_lock_name(lock_classes + class_id); + printk("\n"); + } +} + +static void print_collision(struct task_struct *curr, + struct held_lock *hlock_next, + struct lock_chain *chain) +{ + pr_warn("\n"); + pr_warn("============================\n"); + pr_warn("WARNING: chain_key collision\n"); + print_kernel_ident(); + pr_warn("----------------------------\n"); + pr_warn("%s/%d: ", current->comm, task_pid_nr(current)); + pr_warn("Hash chain already cached but the contents don't match!\n"); + + pr_warn("Held locks:"); + print_chain_keys_held_locks(curr, hlock_next); + + pr_warn("Locks in cached chain:"); + print_chain_keys_chain(chain); + + pr_warn("\nstack backtrace:\n"); + dump_stack(); +} + +/* + * Checks whether the chain and the current held locks are consistent + * in depth and also in content. If they are not it most likely means + * that there was a collision during the calculation of the chain_key. + * Returns: 0 not passed, 1 passed + */ +static int check_no_collision(struct task_struct *curr, + struct held_lock *hlock, + struct lock_chain *chain) +{ + int i, j, id; + + i = get_first_held_lock(curr, hlock); + + if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { + print_collision(curr, hlock, chain); + return 0; + } + + for (j = 0; j < chain->depth - 1; j++, i++) { + id = curr->held_locks[i].class_idx; + + if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { + print_collision(curr, hlock, chain); + return 0; + } + } + return 1; +} + +/* + * Check whether we follow the irq-flags state precisely: + */ +static void check_flags(unsigned long flags) +{ + if (!debug_locks) + return; + + if (irqs_disabled_flags(flags)) { + if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { + printk("possible reason: unannotated irqs-off.\n"); + } + } else { + if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { + printk("possible reason: unannotated irqs-on.\n"); + } + } + + /* + * We dont accurately track softirq state in e.g. + * hardirq contexts (such as on 4KSTACKS), so only + * check if not in hardirq contexts: + */ + if (!hardirq_count()) { + if (softirq_count()) { + /* like the above, but with softirqs */ + DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); + } else { + /* lick the above, does it taste good? */ + DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); + } + } + + if (!debug_locks) + print_irqtrace_events(current); +} + +#define check_lock_chain_key check_lock_chain_key +static bool check_lock_chain_key(struct lock_chain *chain) +{ + u64 chain_key = INITIAL_CHAIN_KEY; + int i; + + for (i = chain->base; i < chain->base + chain->depth; i++) + chain_key = iterate_chain_key(chain_key, chain_hlocks[i]); + /* + * The 'unsigned long long' casts avoid that a compiler warning + * is reported when building tools/lib/lockdep. + */ + if (chain->chain_key != chain_key) { + printk(KERN_INFO "chain %lld: key %#llx <> %#llx\n", + (unsigned long long)(chain - lock_chains), + (unsigned long long)chain->chain_key, + (unsigned long long)chain_key); + return false; + } + return true; +} + +#else +static int check_no_collision(struct task_struct *curr, + struct held_lock *hlock, + struct lock_chain *chain) +{ + return 1; +} + +static void check_flags(unsigned long flags) { } +#endif /* CONFIG_DEBUG_LOCKDEP */ + +/* + * Given an index that is >= -1, return the index of the next lock chain. + * Return -2 if there is no next lock chain. + */ +long lockdep_next_lockchain(long i) +{ + i = find_next_bit(lock_chains_in_use, ARRAY_SIZE(lock_chains), i + 1); + return i < ARRAY_SIZE(lock_chains) ? i : -2; +} + +unsigned long lock_chain_count(void) +{ + return bitmap_weight(lock_chains_in_use, ARRAY_SIZE(lock_chains)); +} + +/* Must be called with the graph lock held. */ +static struct lock_chain *alloc_lock_chain(void) +{ + int idx = find_first_zero_bit(lock_chains_in_use, + ARRAY_SIZE(lock_chains)); + + if (unlikely(idx >= ARRAY_SIZE(lock_chains))) + return NULL; + __set_bit(idx, lock_chains_in_use); + return lock_chains + idx; +} + +/* + * Adds a dependency chain into chain hashtable. And must be called with + * graph_lock held. + * + * Return 0 if fail, and graph_lock is released. + * Return 1 if succeed, with graph_lock held. + */ +static inline int add_chain_cache(struct task_struct *curr, + struct held_lock *hlock, + u64 chain_key) +{ + struct lock_class *class = hlock_class(hlock); + struct hlist_head *hash_head = chainhashentry(chain_key); + struct lock_chain *chain; + int i, j; + + /* + * The caller must hold the graph lock, ensure we've got IRQs + * disabled to make this an IRQ-safe lock.. for recursion reasons + * lockdep won't complain about its own locking errors. + */ + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return 0; + + chain = alloc_lock_chain(); + if (!chain) { + if (!debug_locks_off_graph_unlock()) + return 0; + + print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); + dump_stack(); + return 0; + } + chain->chain_key = chain_key; + chain->irq_context = hlock->irq_context; + i = get_first_held_lock(curr, hlock); + chain->depth = curr->lockdep_depth + 1 - i; + + BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks)); + BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks)); + BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes)); + + j = alloc_chain_hlocks(chain->depth); + if (j < 0) { + if (!debug_locks_off_graph_unlock()) + return 0; + + print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); + dump_stack(); + return 0; + } + + chain->base = j; + for (j = 0; j < chain->depth - 1; j++, i++) { + int lock_id = curr->held_locks[i].class_idx; + + chain_hlocks[chain->base + j] = lock_id; + } + chain_hlocks[chain->base + j] = class - lock_classes; + hlist_add_head_rcu(&chain->entry, hash_head); + debug_atomic_inc(chain_lookup_misses); + inc_chains(chain->irq_context); + + return 1; +} + +/* + * Look up a dependency chain. Must be called with either the graph lock or + * the RCU read lock held. + */ +static inline struct lock_chain *lookup_chain_cache(u64 chain_key) +{ + struct hlist_head *hash_head = chainhashentry(chain_key); + struct lock_chain *chain; + + hlist_for_each_entry_rcu(chain, hash_head, entry) { + if (READ_ONCE(chain->chain_key) == chain_key) { + debug_atomic_inc(chain_lookup_hits); + return chain; + } + } + return NULL; +} + +/* + * If the key is not present yet in dependency chain cache then + * add it and return 1 - in this case the new dependency chain is + * validated. If the key is already hashed, return 0. + * (On return with 1 graph_lock is held.) + */ +static inline int lookup_chain_cache_add(struct task_struct *curr, + struct held_lock *hlock, + u64 chain_key) +{ + struct lock_class *class = hlock_class(hlock); + struct lock_chain *chain = lookup_chain_cache(chain_key); + + if (chain) { +cache_hit: + if (!check_no_collision(curr, hlock, chain)) + return 0; + + if (very_verbose(class)) { + printk("\nhash chain already cached, key: " + "%016Lx tail class: [%px] %s\n", + (unsigned long long)chain_key, + class->key, class->name); + } + + return 0; + } + + if (very_verbose(class)) { + printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n", + (unsigned long long)chain_key, class->key, class->name); + } + + if (!graph_lock()) + return 0; + + /* + * We have to walk the chain again locked - to avoid duplicates: + */ + chain = lookup_chain_cache(chain_key); + if (chain) { + graph_unlock(); + goto cache_hit; + } + + if (!add_chain_cache(curr, hlock, chain_key)) + return 0; + + return 1; +} + +static int validate_chain(struct task_struct *curr, + struct held_lock *hlock, + int chain_head, u64 chain_key) +{ + /* + * Trylock needs to maintain the stack of held locks, but it + * does not add new dependencies, because trylock can be done + * in any order. + * + * We look up the chain_key and do the O(N^2) check and update of + * the dependencies only if this is a new dependency chain. + * (If lookup_chain_cache_add() return with 1 it acquires + * graph_lock for us) + */ + if (!hlock->trylock && hlock->check && + lookup_chain_cache_add(curr, hlock, chain_key)) { + /* + * Check whether last held lock: + * + * - is irq-safe, if this lock is irq-unsafe + * - is softirq-safe, if this lock is hardirq-unsafe + * + * And check whether the new lock's dependency graph + * could lead back to the previous lock: + * + * - within the current held-lock stack + * - across our accumulated lock dependency records + * + * any of these scenarios could lead to a deadlock. + */ + /* + * The simple case: does the current hold the same lock + * already? + */ + int ret = check_deadlock(curr, hlock); + + if (!ret) + return 0; + /* + * Mark recursive read, as we jump over it when + * building dependencies (just like we jump over + * trylock entries): + */ + if (ret == 2) + hlock->read = 2; + /* + * Add dependency only if this lock is not the head + * of the chain, and if it's not a secondary read-lock: + */ + if (!chain_head && ret != 2) { + if (!check_prevs_add(curr, hlock)) + return 0; + } + + graph_unlock(); + } else { + /* after lookup_chain_cache_add(): */ + if (unlikely(!debug_locks)) + return 0; + } + + return 1; +} + +static int mark_lock(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit new_bit); + +static void print_usage_bug_scenario(struct held_lock *lock) +{ + struct lock_class *class = hlock_class(lock); + + printk(" Possible unsafe locking scenario:\n\n"); + printk(" CPU0\n"); + printk(" ----\n"); + printk(" lock("); + __print_lock_name(class); + printk(KERN_CONT ");\n"); + printk(" \n"); + printk(" lock("); + __print_lock_name(class); + printk(KERN_CONT ");\n"); + printk("\n *** DEADLOCK ***\n\n"); +} + +static void +print_usage_bug(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) +{ + if (!debug_locks_off_graph_unlock() || debug_locks_silent) + return; + + pr_warn("\n"); + pr_warn("================================\n"); + pr_warn("WARNING: inconsistent lock state\n"); + print_kernel_ident(); + pr_warn("--------------------------------\n"); + + pr_warn("inconsistent {%s} -> {%s} usage.\n", + usage_str[prev_bit], usage_str[new_bit]); + + pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", + curr->comm, task_pid_nr(curr), + trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, + trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, + trace_hardirqs_enabled(curr), + trace_softirqs_enabled(curr)); + print_lock(this); + + pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]); + print_lock_trace(hlock_class(this)->usage_traces[prev_bit], 1); + + print_irqtrace_events(curr); + pr_warn("\nother info that might help us debug this:\n"); + print_usage_bug_scenario(this); + + lockdep_print_held_locks(curr); + + pr_warn("\nstack backtrace:\n"); + dump_stack(); +} + +/* + * Print out an error if an invalid bit is set: + */ +static inline int +valid_state(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) +{ + if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) { + print_usage_bug(curr, this, bad_bit, new_bit); + return 0; + } + return 1; +} + + +/* + * print irq inversion bug: + */ +static void +print_irq_inversion_bug(struct task_struct *curr, + struct lock_list *root, struct lock_list *other, + struct held_lock *this, int forwards, + const char *irqclass) +{ + struct lock_list *entry = other; + struct lock_list *middle = NULL; + int depth; + + if (!debug_locks_off_graph_unlock() || debug_locks_silent) + return; + + pr_warn("\n"); + pr_warn("========================================================\n"); + pr_warn("WARNING: possible irq lock inversion dependency detected\n"); + print_kernel_ident(); + pr_warn("--------------------------------------------------------\n"); + pr_warn("%s/%d just changed the state of lock:\n", + curr->comm, task_pid_nr(curr)); + print_lock(this); + if (forwards) + pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); + else + pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); + print_lock_name(other->class); + pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); + + pr_warn("\nother info that might help us debug this:\n"); + + /* Find a middle lock (if one exists) */ + depth = get_lock_depth(other); + do { + if (depth == 0 && (entry != root)) { + pr_warn("lockdep:%s bad path found in chain graph\n", __func__); + break; + } + middle = entry; + entry = get_lock_parent(entry); + depth--; + } while (entry && entry != root && (depth >= 0)); + if (forwards) + print_irq_lock_scenario(root, other, + middle ? middle->class : root->class, other->class); + else + print_irq_lock_scenario(other, root, + middle ? middle->class : other->class, root->class); + + lockdep_print_held_locks(curr); + + pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); + root->trace = save_trace(); + if (!root->trace) + return; + print_shortest_lock_dependencies(other, root); + + pr_warn("\nstack backtrace:\n"); + dump_stack(); +} + +/* + * Prove that in the forwards-direction subgraph starting at + * there is no lock matching : + */ +static int +check_usage_forwards(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit bit, const char *irqclass) +{ + int ret; + struct lock_list root; + struct lock_list *uninitialized_var(target_entry); + + root.parent = NULL; + root.class = hlock_class(this); + ret = find_usage_forwards(&root, lock_flag(bit), &target_entry); + if (ret < 0) { + print_bfs_bug(ret); + return 0; + } + if (ret == 1) + return ret; + + print_irq_inversion_bug(curr, &root, target_entry, + this, 1, irqclass); + return 0; +} + +/* + * Prove that in the backwards-direction subgraph starting at + * there is no lock matching : + */ +static int +check_usage_backwards(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit bit, const char *irqclass) +{ + int ret; + struct lock_list root; + struct lock_list *uninitialized_var(target_entry); + + root.parent = NULL; + root.class = hlock_class(this); + ret = find_usage_backwards(&root, lock_flag(bit), &target_entry); + if (ret < 0) { + print_bfs_bug(ret); + return 0; + } + if (ret == 1) + return ret; + + print_irq_inversion_bug(curr, &root, target_entry, + this, 0, irqclass); + return 0; +} + +void print_irqtrace_events(struct task_struct *curr) +{ + printk("irq event stamp: %u\n", curr->irq_events); + printk("hardirqs last enabled at (%u): [<%px>] %pS\n", + curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip, + (void *)curr->hardirq_enable_ip); + printk("hardirqs last disabled at (%u): [<%px>] %pS\n", + curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip, + (void *)curr->hardirq_disable_ip); + printk("softirqs last enabled at (%u): [<%px>] %pS\n", + curr->softirq_enable_event, (void *)curr->softirq_enable_ip, + (void *)curr->softirq_enable_ip); + printk("softirqs last disabled at (%u): [<%px>] %pS\n", + curr->softirq_disable_event, (void *)curr->softirq_disable_ip, + (void *)curr->softirq_disable_ip); +} + +static int HARDIRQ_verbose(struct lock_class *class) +{ +#if HARDIRQ_VERBOSE + return class_filter(class); +#endif + return 0; +} + +static int SOFTIRQ_verbose(struct lock_class *class) +{ +#if SOFTIRQ_VERBOSE + return class_filter(class); +#endif + return 0; +} + +#define STRICT_READ_CHECKS 1 + +static int (*state_verbose_f[])(struct lock_class *class) = { +#define LOCKDEP_STATE(__STATE) \ + __STATE##_verbose, +#include "lockdep_states.h" +#undef LOCKDEP_STATE +}; + +static inline int state_verbose(enum lock_usage_bit bit, + struct lock_class *class) +{ + return state_verbose_f[bit >> LOCK_USAGE_DIR_MASK](class); +} + +typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, + enum lock_usage_bit bit, const char *name); + +static int +mark_lock_irq(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit new_bit) +{ + int excl_bit = exclusive_bit(new_bit); + int read = new_bit & LOCK_USAGE_READ_MASK; + int dir = new_bit & LOCK_USAGE_DIR_MASK; + + /* + * mark USED_IN has to look forwards -- to ensure no dependency + * has ENABLED state, which would allow recursion deadlocks. + * + * mark ENABLED has to look backwards -- to ensure no dependee + * has USED_IN state, which, again, would allow recursion deadlocks. + */ + check_usage_f usage = dir ? + check_usage_backwards : check_usage_forwards; + + /* + * Validate that this particular lock does not have conflicting + * usage states. + */ + if (!valid_state(curr, this, new_bit, excl_bit)) + return 0; + + /* + * Validate that the lock dependencies don't have conflicting usage + * states. + */ + if ((!read || STRICT_READ_CHECKS) && + !usage(curr, this, excl_bit, state_name(new_bit & ~LOCK_USAGE_READ_MASK))) + return 0; + + /* + * Check for read in write conflicts + */ + if (!read) { + if (!valid_state(curr, this, new_bit, excl_bit + LOCK_USAGE_READ_MASK)) + return 0; + + if (STRICT_READ_CHECKS && + !usage(curr, this, excl_bit + LOCK_USAGE_READ_MASK, + state_name(new_bit + LOCK_USAGE_READ_MASK))) + return 0; + } + + if (state_verbose(new_bit, hlock_class(this))) + return 2; + + return 1; +} + +/* + * Mark all held locks with a usage bit: + */ +static int +mark_held_locks(struct task_struct *curr, enum lock_usage_bit base_bit) +{ + struct held_lock *hlock; + int i; + + for (i = 0; i < curr->lockdep_depth; i++) { + enum lock_usage_bit hlock_bit = base_bit; + hlock = curr->held_locks + i; + + if (hlock->read) + hlock_bit += LOCK_USAGE_READ_MASK; + + BUG_ON(hlock_bit >= LOCK_USAGE_STATES); + + if (!hlock->check) + continue; + + if (!mark_lock(curr, hlock, hlock_bit)) + return 0; + } + + return 1; +} + +/* + * Hardirqs will be enabled: + */ +static void __trace_hardirqs_on_caller(unsigned long ip) +{ + struct task_struct *curr = current; + + /* we'll do an OFF -> ON transition: */ + curr->hardirqs_enabled = 1; + + /* + * We are going to turn hardirqs on, so set the + * usage bit for all held locks: + */ + if (!mark_held_locks(curr, LOCK_ENABLED_HARDIRQ)) + return; + /* + * If we have softirqs enabled, then set the usage + * bit for all held locks. (disabled hardirqs prevented + * this bit from being set before) + */ + if (curr->softirqs_enabled) + if (!mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ)) + return; + + curr->hardirq_enable_ip = ip; + curr->hardirq_enable_event = ++curr->irq_events; + debug_atomic_inc(hardirqs_on_events); +} + +void lockdep_hardirqs_on(unsigned long ip) +{ + if (unlikely(!debug_locks || current->lockdep_recursion)) + return; + + if (unlikely(current->hardirqs_enabled)) { + /* + * Neither irq nor preemption are disabled here + * so this is racy by nature but losing one hit + * in a stat is not a big deal. + */ + __debug_atomic_inc(redundant_hardirqs_on); + return; + } + + /* + * We're enabling irqs and according to our state above irqs weren't + * already enabled, yet we find the hardware thinks they are in fact + * enabled.. someone messed up their IRQ state tracing. + */ + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return; + + /* + * See the fine text that goes along with this variable definition. + */ + if (DEBUG_LOCKS_WARN_ON(early_boot_irqs_disabled)) + return; + + /* + * Can't allow enabling interrupts while in an interrupt handler, + * that's general bad form and such. Recursion, limited stack etc.. + */ + if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) + return; + + current->lockdep_recursion = 1; + __trace_hardirqs_on_caller(ip); + current->lockdep_recursion = 0; +} +NOKPROBE_SYMBOL(lockdep_hardirqs_on); + +/* + * Hardirqs were disabled: + */ +void lockdep_hardirqs_off(unsigned long ip) +{ + struct task_struct *curr = current; + + if (unlikely(!debug_locks || current->lockdep_recursion)) + return; + + /* + * So we're supposed to get called after you mask local IRQs, but for + * some reason the hardware doesn't quite think you did a proper job. + */ + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return; + + if (curr->hardirqs_enabled) { + /* + * We have done an ON -> OFF transition: + */ + curr->hardirqs_enabled = 0; + curr->hardirq_disable_ip = ip; + curr->hardirq_disable_event = ++curr->irq_events; + debug_atomic_inc(hardirqs_off_events); + } else + debug_atomic_inc(redundant_hardirqs_off); +} +NOKPROBE_SYMBOL(lockdep_hardirqs_off); + +/* + * Softirqs will be enabled: + */ +void trace_softirqs_on(unsigned long ip) +{ + struct task_struct *curr = current; + + if (unlikely(!debug_locks || current->lockdep_recursion)) + return; + + /* + * We fancy IRQs being disabled here, see softirq.c, avoids + * funny state and nesting things. + */ + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return; + + if (curr->softirqs_enabled) { + debug_atomic_inc(redundant_softirqs_on); + return; + } + + current->lockdep_recursion = 1; + /* + * We'll do an OFF -> ON transition: + */ + curr->softirqs_enabled = 1; + curr->softirq_enable_ip = ip; + curr->softirq_enable_event = ++curr->irq_events; + debug_atomic_inc(softirqs_on_events); + /* + * We are going to turn softirqs on, so set the + * usage bit for all held locks, if hardirqs are + * enabled too: + */ + if (curr->hardirqs_enabled) + mark_held_locks(curr, LOCK_ENABLED_SOFTIRQ); + current->lockdep_recursion = 0; +} + +/* + * Softirqs were disabled: + */ +void trace_softirqs_off(unsigned long ip) +{ + struct task_struct *curr = current; + + if (unlikely(!debug_locks || current->lockdep_recursion)) + return; + + /* + * We fancy IRQs being disabled here, see softirq.c + */ + if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + return; + + if (curr->softirqs_enabled) { + /* + * We have done an ON -> OFF transition: + */ + curr->softirqs_enabled = 0; + curr->softirq_disable_ip = ip; + curr->softirq_disable_event = ++curr->irq_events; + debug_atomic_inc(softirqs_off_events); + /* + * Whoops, we wanted softirqs off, so why aren't they? + */ + DEBUG_LOCKS_WARN_ON(!softirq_count()); + } else + debug_atomic_inc(redundant_softirqs_off); +} + +static int +mark_usage(struct task_struct *curr, struct held_lock *hlock, int check) +{ + if (!check) + goto lock_used; + + /* + * If non-trylock use in a hardirq or softirq context, then + * mark the lock as used in these contexts: + */ + if (!hlock->trylock) { + if (hlock->read) { + if (curr->hardirq_context) + if (!mark_lock(curr, hlock, + LOCK_USED_IN_HARDIRQ_READ)) + return 0; + if (curr->softirq_context) + if (!mark_lock(curr, hlock, + LOCK_USED_IN_SOFTIRQ_READ)) + return 0; + } else { + if (curr->hardirq_context) + if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) + return 0; + if (curr->softirq_context) + if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) + return 0; + } + } + if (!hlock->hardirqs_off) { + if (hlock->read) { + if (!mark_lock(curr, hlock, + LOCK_ENABLED_HARDIRQ_READ)) + return 0; + if (curr->softirqs_enabled) + if (!mark_lock(curr, hlock, + LOCK_ENABLED_SOFTIRQ_READ)) + return 0; + } else { + if (!mark_lock(curr, hlock, + LOCK_ENABLED_HARDIRQ)) + return 0; + if (curr->softirqs_enabled) + if (!mark_lock(curr, hlock, + LOCK_ENABLED_SOFTIRQ)) + return 0; + } + } + +lock_used: + /* mark it as used: */ + if (!mark_lock(curr, hlock, LOCK_USED)) + return 0; + + return 1; +} + +static inline unsigned int task_irq_context(struct task_struct *task) +{ + return LOCK_CHAIN_HARDIRQ_CONTEXT * !!task->hardirq_context + + LOCK_CHAIN_SOFTIRQ_CONTEXT * !!task->softirq_context; +} + +static int separate_irq_context(struct task_struct *curr, + struct held_lock *hlock) +{ + unsigned int depth = curr->lockdep_depth; + + /* + * Keep track of points where we cross into an interrupt context: + */ + if (depth) { + struct held_lock *prev_hlock; + + prev_hlock = curr->held_locks + depth-1; + /* + * If we cross into another context, reset the + * hash key (this also prevents the checking and the + * adding of the dependency to 'prev'): + */ + if (prev_hlock->irq_context != hlock->irq_context) + return 1; + } + return 0; +} + +/* + * Mark a lock with a usage bit, and validate the state transition: + */ +static int mark_lock(struct task_struct *curr, struct held_lock *this, + enum lock_usage_bit new_bit) +{ + unsigned int new_mask = 1 << new_bit, ret = 1; + + if (new_bit >= LOCK_USAGE_STATES) { + DEBUG_LOCKS_WARN_ON(1); + return 0; + } + + /* + * If already set then do not dirty the cacheline, + * nor do any checks: + */ + if (likely(hlock_class(this)->usage_mask & new_mask)) + return 1; + + if (!graph_lock()) + return 0; + /* + * Make sure we didn't race: + */ + if (unlikely(hlock_class(this)->usage_mask & new_mask)) { + graph_unlock(); + return 1; + } + + hlock_class(this)->usage_mask |= new_mask; + + if (!(hlock_class(this)->usage_traces[new_bit] = save_trace())) + return 0; + + switch (new_bit) { + case LOCK_USED: + debug_atomic_dec(nr_unused_locks); + break; + default: + ret = mark_lock_irq(curr, this, new_bit); + if (!ret) + return 0; + } + + graph_unlock(); + + /* + * We must printk outside of the graph_lock: + */ + if (ret == 2) { + printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); + print_lock(this); + print_irqtrace_events(curr); + dump_stack(); + } + + return ret; +} + +/* Remove a class from a lock chain. Must be called with the graph lock held. */ +static void remove_class_from_lock_chain(struct pending_free *pf, + struct lock_chain *chain, + struct lock_class *class) +{ + int i; + + for (i = chain->base; i < chain->base + chain->depth; i++) { + if (chain_hlocks[i] != class - lock_classes) + continue; + /* + * Each lock class occurs at most once in a lock chain so once + * we found a match we can break out of this loop. + */ + goto free_lock_chain; + } + /* Since the chain has not been modified, return. */ + return; + +free_lock_chain: + free_chain_hlocks(chain->base, chain->depth); + /* Overwrite the chain key for concurrent RCU readers. */ + WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY); + dec_chains(chain->irq_context); + + /* + * Note: calling hlist_del_rcu() from inside a + * hlist_for_each_entry_rcu() loop is safe. + */ + hlist_del_rcu(&chain->entry); + __set_bit(chain - lock_chains, pf->lock_chains_being_freed); + nr_zapped_lock_chains++; +} + +/* Must be called with the graph lock held. */ +static void remove_class_from_lock_chains(struct pending_free *pf, + struct lock_class *class) +{ + struct lock_chain *chain; + struct hlist_head *head; + int i; + + for (i = 0; i < ARRAY_SIZE(chainhash_table); i++) { + head = chainhash_table + i; + hlist_for_each_entry_rcu(chain, head, entry) { + remove_class_from_lock_chain(pf, chain, class); + } + } +} -- 2.18.1