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locking/qspinlock: Use smp_store_release() in queued_spin_unlock()

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A qspinlock can be unlocked simply by writing zero to the locked byte.
This can be implemented in the generic code, so do that and remove the
arch-specific override for x86 in the !PV case.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: boqun.feng@gmail.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1524738868-31318-11-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Will Deacon
2018-04-26 11:34:24 +01:00
committed by Ingo Molnar
parent c131a198c4
commit 626e5fbc14
2 changed files with 7 additions and 12 deletions
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2
include/asm-generic/qspinlock.h
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@@ -100,7 +100,7 @@ static __always_inline void queued_spin_unlock(struct qspinlock *lock)
/*
* unlock() needs release semantics:
*/
(void)atomic_sub_return_release(_Q_LOCKED_VAL, &lock->val);
smp_store_release(&lock->locked, 0);
}
#endif