From: Punit Agrawal Date: Mon, 1 Sep 2014 16:16:01 +0000 (+0100) Subject: ARM: 8135/1: Fix in-correct barrier usage in SWP{B} emulation X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e918a62a2ba81d10a3cc2c513dc70034c9524a95;p=linux-beck.git ARM: 8135/1: Fix in-correct barrier usage in SWP{B} emulation According to the ARM ARMv7, explicit barriers are necessary when using synchronisation primitives such as SWP{B}. The use of these instructions does not automatically imply a barrier and any ordering requirements by the software must be explicitly expressed with the use of suitable barriers. Based on this, remove the barriers from SWP{B} emulation. Acked-by: Will Deacon Signed-off-by: Punit Agrawal Signed-off-by: Russell King --- diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c index 67ca8578c6d8..587fdfe1a72c 100644 --- a/arch/arm/kernel/swp_emulate.c +++ b/arch/arm/kernel/swp_emulate.c @@ -142,14 +142,6 @@ static int emulate_swpX(unsigned int address, unsigned int *data, while (1) { unsigned long temp; - /* - * Barrier required between accessing protected resource and - * releasing a lock for it. Legacy code might not have done - * this, and we cannot determine that this is not the case - * being emulated, so insert always. - */ - smp_mb(); - if (type == TYPE_SWPB) __user_swpb_asm(*data, address, res, temp); else @@ -162,13 +154,6 @@ static int emulate_swpX(unsigned int address, unsigned int *data, } if (res == 0) { - /* - * Barrier also required between acquiring a lock for a - * protected resource and accessing the resource. Inserted for - * same reason as above. - */ - smp_mb(); - if (type == TYPE_SWPB) swpbcounter++; else