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Commit 2b2a85a4 authored by Will Deacon's avatar Will Deacon Committed by Ingo Molnar
Browse files

locking/qrwlock: Implement queue_write_unlock() using smp_store_release() 



Since the following commit:

  536fa402 ("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: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarWaiman 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: default avatarIngo Molnar <mingo@kernel.org>
parent f5468ffd

arch/x86/include/asm/qrwlock.h

+0 −10
Original line number Diff line number Diff line
@@ -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 */

include/asm-generic/qrwlock.h

+1 −8
Original line number Diff line number Diff line
@@ -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