Commit-ID: 2b2a85a4d3534b8884fcfa5bb52837f0e1c672bc
Gitweb: http://git.kernel.org/tip/2b2a85a4d3534b8884fcfa5bb52837f0e1c672bc
Author: Will Deacon <will.deacon@xxxxxxx>
AuthorDate: Thu, 6 Aug 2015 17:54:41 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 12 Aug 2015 11:59:05 +0200
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@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Waiman Long <Waiman.Long@xxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1438880084-18856-6-git-send-email-will.deacon@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/qrwlock.h | 10 ----------
include/asm-generic/qrwlock.h | 9 +--------
2 files changed, 1 insertion(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/qrwlock.h b/arch/x86/include/asm/qrwlock.h
index a8810bf..c537cbb 100644
--- a/arch/x86/include/asm/qrwlock.h
+++ b/arch/x86/include/asm/qrwlock.h
@@ -2,16 +2,6 @@
#define _ASM_X86_QRWLOCK_H
#include <asm-generic/qrwlock_types.h>
-
-#ifndef CONFIG_X86_PPRO_FENCE
-#define queued_write_unlock queued_write_unlock
-static inline void queued_write_unlock(struct qrwlock *lock)
-{
- barrier();
- ACCESS_ONCE(*(u8 *)&lock->cnts) = 0;
-}
-#endif
-
#include <asm-generic/qrwlock.h>
#endif /* _ASM_X86_QRWLOCK_H */
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
index deb9e8b..eb673dd 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
--
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