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-Url: http://git.mmlx.us/?a=commitdiff_plain;h=42b5bb47a62b7b2d8cd0b9af58f914c5e83ef76e;p=linux-edison.git arm64: spinlock: retry trylock operation if strex fails on free lock commit 4ecf7ccb1973fd826456b6ab1e6dfafe9023c753 upstream. 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 Cc: Mark Brown Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index 7065e920149..0defa0728a9 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)