Messages in this thread Patch in this message | | | From | Davidlohr Bueso <> | Subject | [PATCH 1/4] locking/rwsem: Avoid stale ->count for rwsem_down_write_failed() | Date | Sun, 8 May 2016 21:56:07 -0700 |
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The field is obviously updated w.o the lock and needs a READ_ONCE while waiting for lock holder(s) to go away, just like we do with all other ->count accesses.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de> --- kernel/locking/rwsem-xadd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index df4dcb883b50..7d62772600cf 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -494,7 +494,7 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) } schedule(); set_current_state(state); - } while ((count = sem->count) & RWSEM_ACTIVE_MASK); + } while ((count = READ_ONCE(sem->count)) & RWSEM_ACTIVE_MASK); raw_spin_lock_irq(&sem->wait_lock); } -- 2.8.1
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