From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753743AbeAQPQT (ORCPT + 1 other); Wed, 17 Jan 2018 10:16:19 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:33993 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752698AbeAQPOi (ORCPT ); Wed, 17 Jan 2018 10:14:38 -0500 From: Matthew Wilcox To: Peter Zijlstra , Ingo Molnar Cc: "David S. Miller" , Matthew Wilcox , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: [PATCH 1/3] lockdep: Assign lock keys on registration Date: Wed, 17 Jan 2018 07:14:12 -0800 Message-Id: <20180117151414.23686-2-willy@infradead.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180117151414.23686-1-willy@infradead.org> References: <20180117151414.23686-1-willy@infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Matthew Wilcox Lockdep was assigning lock keys when a lock was looked up. This is unnecessary; if the lock has never been registered then we know it is not locked. It also complicates the calling convention. Switch to assigning the lock key in register_lock_class(). Signed-off-by: Matthew Wilcox --- kernel/locking/lockdep.c | 76 +++++++++++++++++++++++++----------------------- 1 file changed, 40 insertions(+), 36 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 5fa1324a4f29..472547dd45c3 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -647,18 +647,12 @@ static int count_matching_names(struct lock_class *new_class) return count + 1; } -/* - * 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 inline struct lock_class * look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) { struct lockdep_subclass_key *key; struct hlist_head *hash_head; struct lock_class *class; - bool is_static = false; if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { debug_locks_off(); @@ -671,24 +665,11 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) } /* - * Static locks do not have their class-keys yet - for them the key - * is the lock object itself. If the lock is in the per cpu area, - * the canonical address of the lock (per cpu offset removed) is - * used. + * If it is not initialised then it has never been locked, + * so it won't be present in the hash table. */ - if (unlikely(!lock->key)) { - unsigned long can_addr, addr = (unsigned long)lock; - - if (__is_kernel_percpu_address(addr, &can_addr)) - lock->key = (void *)can_addr; - else if (__is_module_percpu_address(addr, &can_addr)) - lock->key = (void *)can_addr; - else if (static_obj(lock)) - lock->key = (void *)lock; - else - return ERR_PTR(-EINVAL); - is_static = true; - } + if (unlikely(!lock->key)) + return NULL; /* * NOTE: the class-key must be unique. For dynamic locks, a static @@ -720,7 +701,35 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) } } - return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL); + return NULL; +} + +/* + * Static locks do not have their class-keys yet - for them the key is + * the lock object itself. If the lock is in the per cpu area, the + * canonical address of the lock (per cpu offset removed) is used. + */ +static bool assign_lock_key(struct lockdep_map *lock) +{ + unsigned long can_addr, addr = (unsigned long)lock; + + if (__is_kernel_percpu_address(addr, &can_addr)) + lock->key = (void *)can_addr; + else if (__is_module_percpu_address(addr, &can_addr)) + lock->key = (void *)can_addr; + else if (static_obj(lock)) + lock->key = (void *)lock; + else { + /* Debug-check: all keys must be persistent! */ + debug_locks_off(); + pr_err("INFO: trying to register non-static key.\n"); + pr_err("the code is fine but needs lockdep annotation.\n"); + pr_err("turning off the locking correctness validator.\n"); + dump_stack(); + return false; + } + + return true; } /* @@ -738,18 +747,13 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) DEBUG_LOCKS_WARN_ON(!irqs_disabled()); class = look_up_lock_class(lock, subclass); - if (likely(!IS_ERR_OR_NULL(class))) + if (likely(class)) goto out_set_class_cache; - /* - * Debug-check: all keys must be persistent! - */ - if (IS_ERR(class)) { - debug_locks_off(); - printk("INFO: trying to register non-static key.\n"); - printk("the code is fine but needs lockdep annotation.\n"); - printk("turning off the locking correctness validator.\n"); - dump_stack(); + if (!lock->key) { + if (!assign_lock_key(lock)) + return NULL; + } else if (!static_obj(lock->key)) { return NULL; } @@ -3498,7 +3502,7 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock) * Clearly if the lock hasn't been acquired _ever_, we're not * holding it either, so report failure. */ - if (IS_ERR_OR_NULL(class)) + if (!class) return 0; /* @@ -4294,7 +4298,7 @@ void lockdep_reset_lock(struct lockdep_map *lock) * If the class exists we look it up and zap it: */ class = look_up_lock_class(lock, j); - if (!IS_ERR_OR_NULL(class)) + if (class) zap_class(class); } /* -- 2.15.1