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ARM: 8098/1: mcs lock: implement wfe-based polling for MCS locking 

This patch introduces a wfe-based polling loop for spinning on contended
MCS locks and waking up corresponding waiters when the lock is released.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon 2014-07-09 19:31:28 +01:00 committed by Russell King
parent e38361d032
commit bf67fd3142
1 changed files with 23 additions and 0 deletions
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23
arch/arm/include/asm/mcs_spinlock.h Normal file
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#ifndef __ASM_MCS_LOCK_H
#define __ASM_MCS_LOCK_H
#ifdef CONFIG_SMP
#include <asm/spinlock.h>
/* MCS spin-locking. */
#define arch_mcs_spin_lock_contended(lock) \
do { \
/* Ensure prior stores are observed before we enter wfe. */ \
smp_mb(); \
while (!(smp_load_acquire(lock))) \
wfe(); \
} while (0) \
#define arch_mcs_spin_unlock_contended(lock) \
do { \
smp_store_release(lock, 1); \
dsb_sev(); \
} while (0)
#endif /* CONFIG_SMP */
#endif /* __ASM_MCS_LOCK_H */