From 4ecf7ccb1973fd826456b6ab1e6dfafe9023c753 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 31 May 2013 16:30:58 +0100 Subject: [PATCH] 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 --- arch/arm64/include/asm/spinlock.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) 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) -- 2.7.4