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| author | Waiman Long <longman@redhat.com> | 2018-03-30 17:27:58 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-03-31 07:30:50 +0200 |
| commit | 5149cbac4235e12a34cf089592a8bd1c9fcfa467 (patch) | |
| tree | dc8965899aaab98faf1c1f0b7319fd1af2dde616 /kernel/locking/rwsem.h | |
| parent | 169310f71fc820fe153ec04c6a111e444a68d6d5 (diff) | |
| download | linux-5149cbac4235e12a34cf089592a8bd1c9fcfa467.tar.gz linux-5149cbac4235e12a34cf089592a8bd1c9fcfa467.tar.bz2 linux-5149cbac4235e12a34cf089592a8bd1c9fcfa467.zip | |
locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches
For a rwsem, locking can either be exclusive or shared. The corresponding
exclusive or shared unlock must be used. Otherwise, the protected data
structures may get corrupted or the lock may be in an inconsistent state.
In order to detect such anomaly, a new configuration option DEBUG_RWSEMS
is added which can be enabled to look for such mismatches and print
warnings that that happens.
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
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>
Link: http://lkml.kernel.org/r/1522445280-7767-2-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking/rwsem.h')
| -rw-r--r-- | kernel/locking/rwsem.h | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h index a883b8f1fdc6..a17cba8d94bb 100644 --- a/kernel/locking/rwsem.h +++ b/kernel/locking/rwsem.h @@ -16,6 +16,12 @@ */ #define RWSEM_READER_OWNED ((struct task_struct *)1UL) +#ifdef CONFIG_DEBUG_RWSEMS +# define DEBUG_RWSEMS_WARN_ON(c) DEBUG_LOCKS_WARN_ON(c) +#else +# define DEBUG_RWSEMS_WARN_ON(c) +#endif + #ifdef CONFIG_RWSEM_SPIN_ON_OWNER /* * All writes to owner are protected by WRITE_ONCE() to make sure that @@ -41,7 +47,7 @@ static inline void rwsem_set_reader_owned(struct rw_semaphore *sem) * do a write to the rwsem cacheline when it is really necessary * to minimize cacheline contention. */ - if (sem->owner != RWSEM_READER_OWNED) + if (READ_ONCE(sem->owner) != RWSEM_READER_OWNED) WRITE_ONCE(sem->owner, RWSEM_READER_OWNED); } |