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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 AA8A7C433FF for ; Mon, 29 Jul 2019 04:47:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7BF1B21655 for ; Mon, 29 Jul 2019 04:47:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726425AbfG2Erq (ORCPT ); Mon, 29 Jul 2019 00:47:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:57338 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726164AbfG2Erp (ORCPT ); Mon, 29 Jul 2019 00:47:45 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id D3B2BAC2E; Mon, 29 Jul 2019 04:47:43 +0000 (UTC) From: Davidlohr Bueso To: mingo@kernel.org, peterz@infradead.org Cc: longman@redhat.com, linux-kernel@vger.kernel.org, Davidlohr Bueso , Davidlohr Bueso Subject: [PATCH -tip] locking/rwsem: Check for operations on an uninitialized rwsem Date: Sun, 28 Jul 2019 21:47:35 -0700 Message-Id: <20190729044735.9632-1-dave@stgolabs.net> X-Mailer: git-send-email 2.16.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently rwsems is the only locking primitive that lacks this debug feature. Add it under CONFIG_DEBUG_RWSEMS and do the magic checking in the locking fastpath (trylock) operation such that we cover all cases. The unlocking part is pretty straightforward. Signed-off-by: Davidlohr Bueso --- include/linux/rwsem.h | 10 ++++++++++ kernel/locking/rwsem.c | 22 ++++++++++++++++++---- 2 files changed, 28 insertions(+), 4 deletions(-) diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index 9d9c663987d8..00d6054687dd 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -45,6 +45,9 @@ struct rw_semaphore { #endif raw_spinlock_t wait_lock; struct list_head wait_list; +#ifdef CONFIG_DEBUG_RWSEMS + void *magic; +#endif #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif @@ -73,6 +76,12 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) # define __RWSEM_DEP_MAP_INIT(lockname) #endif +#ifdef CONFIG_DEBUG_RWSEMS +# define __DEBUG_RWSEM_INITIALIZER(lockname) , .magic = &lockname +#else +# define __DEBUG_RWSEM_INITIALIZER(lockname) +#endif + #ifdef CONFIG_RWSEM_SPIN_ON_OWNER #define __RWSEM_OPT_INIT(lockname) , .osq = OSQ_LOCK_UNLOCKED #else @@ -85,6 +94,7 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) .wait_list = LIST_HEAD_INIT((name).wait_list), \ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(name.wait_lock) \ __RWSEM_OPT_INIT(name) \ + __DEBUG_RWSEM_INITIALIZER(name) \ __RWSEM_DEP_MAP_INIT(name) } #define DECLARE_RWSEM(name) \ diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 37524a47f002..ab392ec51252 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -105,8 +105,9 @@ #ifdef CONFIG_DEBUG_RWSEMS # define DEBUG_RWSEMS_WARN_ON(c, sem) do { \ if (!debug_locks_silent && \ - WARN_ONCE(c, "DEBUG_RWSEMS_WARN_ON(%s): count = 0x%lx, owner = 0x%lx, curr 0x%lx, list %sempty\n",\ + WARN_ONCE(c, "DEBUG_RWSEMS_WARN_ON(%s): count = 0x%lx, magic = 0x%lx, owner = 0x%lx, curr 0x%lx, list %sempty\n",\ #c, atomic_long_read(&(sem)->count), \ + (unsigned long) sem->magic, \ atomic_long_read(&(sem)->owner), (long)current, \ list_empty(&(sem)->wait_list) ? "" : "not ")) \ debug_locks_off(); \ @@ -329,6 +330,9 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name, */ debug_check_no_locks_freed((void *)sem, sizeof(*sem)); lockdep_init_map(&sem->dep_map, name, key, 0); +#endif +#ifdef CONFIG_DEBUG_RWSEMS + sem->magic = sem; #endif atomic_long_set(&sem->count, RWSEM_UNLOCKED_VALUE); raw_spin_lock_init(&sem->wait_lock); @@ -1322,11 +1326,14 @@ static inline int __down_read_killable(struct rw_semaphore *sem) static inline int __down_read_trylock(struct rw_semaphore *sem) { + long tmp; + + DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem); + /* * Optimize for the case when the rwsem is not locked at all. */ - long tmp = RWSEM_UNLOCKED_VALUE; - + tmp = RWSEM_UNLOCKED_VALUE; do { if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, tmp + RWSEM_READER_BIAS)) { @@ -1367,8 +1374,11 @@ static inline int __down_write_killable(struct rw_semaphore *sem) static inline int __down_write_trylock(struct rw_semaphore *sem) { - long tmp = RWSEM_UNLOCKED_VALUE; + long tmp; + DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem); + + tmp = RWSEM_UNLOCKED_VALUE; if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, RWSEM_WRITER_LOCKED)) { rwsem_set_owner(sem); @@ -1384,7 +1394,9 @@ inline void __up_read(struct rw_semaphore *sem) { long tmp; + DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem); DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem); + rwsem_clear_reader_owned(sem); tmp = atomic_long_add_return_release(-RWSEM_READER_BIAS, &sem->count); DEBUG_RWSEMS_WARN_ON(tmp < 0, sem); @@ -1402,12 +1414,14 @@ static inline void __up_write(struct rw_semaphore *sem) { long tmp; + DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem); /* * sem->owner may differ from current if the ownership is transferred * to an anonymous writer by setting the RWSEM_NONSPINNABLE bits. */ DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE), sem); + rwsem_clear_owner(sem); tmp = atomic_long_fetch_add_release(-RWSEM_WRITER_LOCKED, &sem->count); if (unlikely(tmp & RWSEM_FLAG_WAITERS)) -- 2.16.4