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authorWill Deacon <will.deacon@arm.com>2015-08-06 19:54:41 +0300
committerIngo Molnar <mingo@kernel.org>2015-08-12 12:59:05 +0300
commit2b2a85a4d3534b8884fcfa5bb52837f0e1c672bc (patch)
treee81e07f44f5018c49ffda73aefd2e3cc9bb19291 /include/asm-generic/qrwlock.h
parentf5468ffde13fc991bd4d6bdec507ffd5777865bd (diff)
downloadlinux-2b2a85a4d3534b8884fcfa5bb52837f0e1c672bc.tar.xz
locking/qrwlock: Implement queue_write_unlock() using smp_store_release()
Since the following commit: 536fa402221f ("compiler: Allow 1- and 2-byte smp_load_acquire() and smp_store_release()") smp_store_release() supports byte accesses, so use that in writer unlock and remove the conditional macro override. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Waiman Long <Waiman.Long@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-6-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/asm-generic/qrwlock.h')
-rw-r--r--include/asm-generic/qrwlock.h9
1 files changed, 1 insertions, 8 deletions
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
index deb9e8b0eb9e..eb673dde8879 100644
--- a/include/asm-generic/qrwlock.h
+++ b/include/asm-generic/qrwlock.h
@@ -134,21 +134,14 @@ static inline void queued_read_unlock(struct qrwlock *lock)
atomic_sub(_QR_BIAS, &lock->cnts);
}
-#ifndef queued_write_unlock
/**
* queued_write_unlock - release write lock of a queue rwlock
* @lock : Pointer to queue rwlock structure
*/
static inline void queued_write_unlock(struct qrwlock *lock)
{
- /*
- * If the writer field is atomic, it can be cleared directly.
- * Otherwise, an atomic subtraction will be used to clear it.
- */
- smp_mb__before_atomic();
- atomic_sub(_QW_LOCKED, &lock->cnts);
+ smp_store_release((u8 *)&lock->cnts, 0);
}
-#endif
/*
* Remapping rwlock architecture specific functions to the corresponding