From 42b5bb47a62b7b2d8cd0b9af58f914c5e83ef76e Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 31 May 2013 16:30:58 +0100 Subject: 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 --- arch/arm64/include/asm/spinlock.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/arm64') 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) -- cgit v1.2.3