From ab306cae660e524edbeb8889e4e23d3c97717b9c Mon Sep 17 00:00:00 2001
From: Chris Metcalf <cmetcalf@tilera.com>
Date: Fri, 30 Mar 2012 15:46:29 -0400
Subject: arch/tile: use atomic exchange in arch_write_unlock()
This idiom is used elsewhere when we do an unlock by writing a zero,
but I missed it here. Using an atomic operation avoids waiting
on the write buffer for the unlocking write to be sent to the home cache.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
---
arch/tile/include/asm/spinlock_64.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'arch/tile')
diff --git a/arch/tile/include/asm/spinlock_64.h b/arch/tile/include/asm/spinlock_64.h
index 72be5904e020..5f8b6a095fd8 100644
--- a/arch/tile/include/asm/spinlock_64.h
+++ b/arch/tile/include/asm/spinlock_64.h
@@ -137,7 +137,7 @@ static inline void arch_read_unlock(arch_rwlock_t *rw)
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
__insn_mf();
- rw->lock = 0;
+ __insn_exch4(&rw->lock, 0); /* Avoid waiting in the write buffer. */
}
static inline int arch_read_trylock(arch_rwlock_t *rw)
--
cgit v1.2.3