From: Catalin Marinas Date: Fri, 31 May 2013 15:30:58 +0000 (+0100) Subject: arm64: spinlock: retry trylock operation if strex fails on free lock X-Git-Tag: v3.11-rc1~80^2~15 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4ecf7ccb1973fd826456b6ab1e6dfafe9023c753;p=platform%2Fkernel%2Flinux-stable.git arm64: spinlock: retry trylock operation if strex fails on free lock An exclusive store instruction may fail for reasons other than lock contention (e.g. a cache eviction during the critical section) so, in line with other architectures using similar exclusive instructions (alpha, mips, powerpc), retry the trylock operation if the lock appears to be free but the strex reported failure. Signed-off-by: Catalin Marinas Reported-by: Tony Thompson Acked-by: Will Deacon --- diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index 7065e92..0defa07 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -59,9 +59,10 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) unsigned int tmp; asm volatile( - " ldaxr %w0, %1\n" + "2: ldaxr %w0, %1\n" " cbnz %w0, 1f\n" " stxr %w0, %w2, %1\n" + " cbnz %w0, 2b\n" "1:\n" : "=&r" (tmp), "+Q" (lock->lock) : "r" (1)