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| author | Punit Agrawal <punit.agrawal@arm.com> | 2014-09-01 18:16:01 +0200 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-09-12 18:38:58 +0200 |
| commit | e918a62a2ba81d10a3cc2c513dc70034c9524a95 (patch) | |
| tree | 6f2c9f379f791a251319be69149d0061b5672aeb /arch/arm/kernel/swp_emulate.c | |
| parent | ARM: 8133/1: use irq_set_affinity with force=false when migrating irqs (diff) | |
| download | linux-e918a62a2ba81d10a3cc2c513dc70034c9524a95.tar.xz linux-e918a62a2ba81d10a3cc2c513dc70034c9524a95.zip | |
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 <will.deacon@arm.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/swp_emulate.c')
| -rw-r--r-- | arch/arm/kernel/swp_emulate.c | 15 |
1 files changed, 0 insertions, 15 deletions
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 |