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From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org, linux-xtensa@linux-xtensa.org,
	Davidlohr Bueso <dave@stgolabs.net>,
	linux-ia64@vger.kernel.org, Tim Chen <tim.c.chen@linux.intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-sh@vger.kernel.org, linux-hexagon@vger.kernel.org,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Borislav Petkov <bp@alien8.de>,
	linux-alpha@vger.kernel.org, sparclinux@vger.kernel.org,
	Waiman Long <longman@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linuxppc-dev@lists.ozlabs.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH-tip 08/22] locking/rwsem: Add debug check for __down_read*()
Date: Thu,  7 Feb 2019 14:07:12 -0500
Message-ID: <1549566446-27967-9-git-send-email-longman@redhat.com> (raw)
In-Reply-To: <1549566446-27967-1-git-send-email-longman@redhat.com>

When rwsem_down_read_failed*() return, the read lock is acquired
indirectly by others. So debug checks are added in __down_read() and
__down_read_killable() to make sure the rwsem is really reader-owned.

The other debug check calls in kernel/locking/rwsem.c except the
one in up_read_non_owner() are also moved over to rwsem-xadd.h.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 kernel/locking/rwsem-xadd.h | 12 ++++++++++--
 kernel/locking/rwsem.c      |  3 ---
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/locking/rwsem-xadd.h b/kernel/locking/rwsem-xadd.h
index 64e7d62..77151c3 100644
--- a/kernel/locking/rwsem-xadd.h
+++ b/kernel/locking/rwsem-xadd.h
@@ -165,10 +165,13 @@ static inline void rwsem_clear_reader_owned(struct rw_semaphore *sem)
  */
 static inline void __down_read(struct rw_semaphore *sem)
 {
-	if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0))
+	if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) {
 		rwsem_down_read_failed(sem);
-	else
+		DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner &
+					RWSEM_READER_OWNED));
+	} else {
 		rwsem_set_reader_owned(sem);
+	}
 }
 
 static inline int __down_read_killable(struct rw_semaphore *sem)
@@ -176,6 +179,8 @@ static inline int __down_read_killable(struct rw_semaphore *sem)
 	if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) {
 		if (IS_ERR(rwsem_down_read_failed_killable(sem)))
 			return -EINTR;
+		DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner &
+					RWSEM_READER_OWNED));
 	} else {
 		rwsem_set_reader_owned(sem);
 	}
@@ -243,6 +248,7 @@ static inline void __up_read(struct rw_semaphore *sem)
 {
 	long tmp;
 
+	DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED));
 	rwsem_clear_reader_owned(sem);
 	tmp = atomic_long_dec_return_release(&sem->count);
 	if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
@@ -254,6 +260,7 @@ static inline void __up_read(struct rw_semaphore *sem)
  */
 static inline void __up_write(struct rw_semaphore *sem)
 {
+	DEBUG_RWSEMS_WARN_ON(sem->owner != current);
 	rwsem_clear_owner(sem);
 	if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS,
 						    &sem->count) < 0))
@@ -274,6 +281,7 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
 	 * read-locked region is ok to be re-ordered into the
 	 * write side. As such, rely on RELEASE semantics.
 	 */
+	DEBUG_RWSEMS_WARN_ON(sem->owner != current);
 	tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS, &sem->count);
 	rwsem_set_reader_owned(sem);
 	if (tmp < 0)
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index b3b4582..598fc7c 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -114,7 +114,6 @@ int down_write_trylock(struct rw_semaphore *sem)
 void up_read(struct rw_semaphore *sem)
 {
 	rwsem_release(&sem->dep_map, 1, _RET_IP_);
-	DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED));
 
 	__up_read(sem);
 }
@@ -127,7 +126,6 @@ void up_read(struct rw_semaphore *sem)
 void up_write(struct rw_semaphore *sem)
 {
 	rwsem_release(&sem->dep_map, 1, _RET_IP_);
-	DEBUG_RWSEMS_WARN_ON(sem->owner != current);
 
 	__up_write(sem);
 }
@@ -140,7 +138,6 @@ void up_write(struct rw_semaphore *sem)
 void downgrade_write(struct rw_semaphore *sem)
 {
 	lock_downgrade(&sem->dep_map, _RET_IP_);
-	DEBUG_RWSEMS_WARN_ON(sem->owner != current);
 
 	__downgrade_write(sem);
 }
-- 
1.8.3.1


  parent reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-07 19:07 [PATCH-tip 00/22] locking/rwsem: Rework rwsem-xadd & enable new rwsem features Waiman Long
2019-02-07 19:07 ` [PATCH-tip 01/22] locking/qspinlock_stat: Introduce a generic lockevent counting APIs Waiman Long
2019-02-07 19:07 ` [PATCH-tip 02/22] locking/lock_events: Make lock_events available for all archs & other locks Waiman Long
2019-02-07 19:07 ` [PATCH-tip 03/22] locking/rwsem: Relocate rwsem_down_read_failed() Waiman Long
2019-02-07 19:07 ` [PATCH-tip 04/22] locking/rwsem: Remove arch specific rwsem files Waiman Long
2019-02-07 19:36   ` Peter Zijlstra
2019-02-07 19:43     ` Waiman Long
2019-02-07 19:48     ` Peter Zijlstra
2019-02-07 19:07 ` [PATCH-tip 05/22] locking/rwsem: Move owner setting code from rwsem.c to rwsem.h Waiman Long
2019-02-07 19:07 ` [PATCH-tip 06/22] locking/rwsem: Rename kernel/locking/rwsem.h Waiman Long
2019-02-07 19:07 ` [PATCH-tip 07/22] locking/rwsem: Move rwsem internal function declarations to rwsem-xadd.h Waiman Long
2019-02-07 19:07 ` Waiman Long [this message]
2019-02-07 19:07 ` [PATCH-tip 09/22] locking/rwsem: Enhance DEBUG_RWSEMS_WARN_ON() macro Waiman Long
2019-02-07 19:07 ` [PATCH-tip 10/22] locking/rwsem: Enable lock event counting Waiman Long
2019-02-07 19:07 ` [PATCH-tip 11/22] locking/rwsem: Implement a new locking scheme Waiman Long
2019-02-07 19:07 ` [PATCH-tip 12/22] locking/rwsem: Implement lock handoff to prevent lock starvation Waiman Long
2019-02-07 19:07 ` [PATCH-tip 13/22] locking/rwsem: Remove rwsem_wake() wakeup optimization Waiman Long
2019-02-07 19:07 ` [PATCH-tip 14/22] locking/rwsem: Add more rwsem owner access helpers Waiman Long
2019-02-07 19:07 ` [PATCH-tip 15/22] locking/rwsem: Merge owner into count on x86-64 Waiman Long
2019-02-07 19:45   ` Peter Zijlstra
2019-02-07 19:55     ` Waiman Long
2019-02-07 20:08   ` Peter Zijlstra
2019-02-07 20:54     ` Waiman Long
2019-02-08 14:19       ` Waiman Long
2019-02-07 19:07 ` [PATCH-tip 16/22] locking/rwsem: Remove redundant computation of writer lock word Waiman Long
2019-02-07 19:07 ` [PATCH-tip 17/22] locking/rwsem: Recheck owner if it is not on cpu Waiman Long
2019-02-07 19:07 ` [PATCH-tip 18/22] locking/rwsem: Make rwsem_spin_on_owner() return a tri-state value Waiman Long
2019-02-07 19:07 ` [PATCH-tip 19/22] locking/rwsem: Enable readers spinning on writer Waiman Long
2019-02-07 19:07 ` [PATCH-tip 20/22] locking/rwsem: Enable count-based spinning on reader Waiman Long
2019-02-07 19:07 ` [PATCH-tip 21/22] locking/rwsem: Wake up all readers in wait queue Waiman Long
2019-02-07 19:07 ` [PATCH-tip 22/22] locking/rwsem: Ensure an RT task will not spin on reader Waiman Long
2019-02-07 19:51 ` [PATCH-tip 00/22] locking/rwsem: Rework rwsem-xadd & enable new rwsem features Davidlohr Bueso
2019-02-07 20:00   ` Waiman Long
2019-02-11  7:38     ` Ingo Molnar
2019-02-08 19:50 ` Linus Torvalds
2019-02-08 20:31   ` Waiman Long
2019-02-09  0:03     ` Linus Torvalds
2019-02-14 13:23     ` Davidlohr Bueso
2019-02-14 15:22       ` Waiman Long
2019-02-13  9:19 ` Chen Rong
2019-02-13 19:56   ` Linus Torvalds
2019-04-10  8:15     ` huang ying
2019-04-10 16:08       ` Waiman Long
2019-04-12  0:49         ` huang ying

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