[PATCH 4/6] MIPS: Octeon: qspinlock: Exclude mmiowb()

[Alexander A Sverdlin]

From: Alexander Sverdlin <alexander.sverd...@nokia.com>

On Octeon mmiowb() is SYNCW, which is already contained in
smp_store_release(). Removing superfluous barrier brings around 10%
performance on uncontended tight spinlock loops.

Signed-off-by: Alexander Sverdlin <alexander.sverd...@nokia.com>
---
 arch/mips/include/asm/spinlock.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index 0a707f3..fbe97b4 100644
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -21,8 +21,10 @@
  */
 static inline void queued_spin_unlock(struct qspinlock *lock)
 {
+#ifndef CONFIG_CPU_CAVIUM_OCTEON
        /* This could be optimised with ARCH_HAS_MMIOWB */
        mmiowb();
+#endif
        smp_store_release(&lock->locked, 0);
 #ifdef CONFIG_CPU_CAVIUM_OCTEON
        nudge_writes();
-- 
2.10.2