lkml.org 
[lkml]   [2019]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:locking/core] locking/rwsem: Add debug check for __down_read*()
Commit-ID:  a68e2c4c637918da47b3aa270051545cff7d8245
Gitweb: https://git.kernel.org/tip/a68e2c4c637918da47b3aa270051545cff7d8245
Author: Waiman Long <longman@redhat.com>
AuthorDate: Thu, 4 Apr 2019 13:43:14 -0400
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 10 Apr 2019 10:56:02 +0200

locking/rwsem: Add debug check for __down_read*()

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>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-6-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/locking/rwsem.c | 3 ---
kernel/locking/rwsem.h | 12 ++++++++++--
2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 59e584895532..90de5f1780ba 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -109,7 +109,6 @@ EXPORT_SYMBOL(down_write_trylock);
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);
}
@@ -122,7 +121,6 @@ EXPORT_SYMBOL(up_read);
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);
}
@@ -135,7 +133,6 @@ EXPORT_SYMBOL(up_write);
void downgrade_write(struct rw_semaphore *sem)
{
lock_downgrade(&sem->dep_map, _RET_IP_);
- DEBUG_RWSEMS_WARN_ON(sem->owner != current);

__downgrade_write(sem);
}
diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h
index 19997c82270b..1d8f722a6761 100644
--- a/kernel/locking/rwsem.h
+++ b/kernel/locking/rwsem.h
@@ -165,10 +165,13 @@ extern struct rw_semaphore *rwsem_downgrade_wake(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);
}
@@ -246,6 +251,7 @@ 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))
@@ -257,6 +263,7 @@ 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))
@@ -277,6 +284,7 @@ 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)
\
 
 \ /
  Last update: 2019-04-16 12:07    [W:0.170 / U:8.952 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site