From 5dab26af1bacad9a7189d904fbc8b4fe8e95dd81 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 4 Mar 2011 12:38:54 +0100 Subject: ARM: 6784/1: errata: no automatic Store Buffer drain on Cortex-A9 On revisions of the Cortex-A9 prior to r2p0, the Store Buffer does not have any automatic draining mechanism and therefore a livelock may occur if an external agent continuously polls a memory location waiting to observe an update. This workaround defines cpu_relax() as smp_mb(), preventing correctly written polling loops from denying visibility of updates to memory. Acked-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/include/asm/processor.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm/include/asm/processor.h') diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h index 67357baaeeeb..7a1f03c10f1b 100644 --- a/arch/arm/include/asm/processor.h +++ b/arch/arm/include/asm/processor.h @@ -95,7 +95,7 @@ extern void release_thread(struct task_struct *); unsigned long get_wchan(struct task_struct *p); -#if __LINUX_ARM_ARCH__ == 6 +#if __LINUX_ARM_ARCH__ == 6 || defined(CONFIG_ARM_ERRATA_754327) #define cpu_relax() smp_mb() #else #define cpu_relax() barrier() -- cgit v1.2.3