linux-kernel - [PATCH 3/3] MIPS: bugfix - replace smp_mb with release barrier function in unlocks

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Message-ID: <20150602000952.6668.82483.stgit@ubuntu-yegoshin>
Date:	Mon, 1 Jun 2015 17:09:52 -0700
From:	Leonid Yegoshin <Leonid.Yegoshin@...tec.com>
To:	<linux-mips@...ux-mips.org>, <benh@...nel.crashing.org>,
	<will.deacon@....com>, <linux-kernel@...r.kernel.org>,
	<ralf@...ux-mips.org>, <markos.chandras@...tec.com>,
	<macro@...ux-mips.org>, <Steven.Hill@...tec.com>,
	<alexander.h.duyck@...hat.com>, <davem@...emloft.net>
Subject: [PATCH 3/3] MIPS: bugfix - replace smp_mb with release barrier
 function in unlocks

Repleace smp_mb() in arch_write_unlock() and __clear_bit_unlock() to
smp_mb__before_llsc() call which does "release" barrier functionality.

It seems like it was missed in commit f252ffd50c97dae87b45f1dbad24f71358ccfbd6
during introduction of "acquire" and "release" semantics.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@...tec.com>
---
 arch/mips/include/asm/bitops.h   |    2 +-
 arch/mips/include/asm/spinlock.h |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
index 0cf29bd5dc5c..ce9666cf1499 100644
--- a/arch/mips/include/asm/bitops.h
+++ b/arch/mips/include/asm/bitops.h
@@ -469,7 +469,7 @@ static inline int test_and_change_bit(unsigned long nr,
  */
 static inline void __clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)
 {
-	smp_mb();
+	smp_mb__before_llsc();
 	__clear_bit(nr, addr);
 }
 
diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index 1fca2e0793dc..7c7f3b2bd3de 100644
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -317,7 +317,7 @@ static inline void arch_write_lock(arch_rwlock_t *rw)
 
 static inline void arch_write_unlock(arch_rwlock_t *rw)
 {
-	smp_mb();
+	smp_mb__before_llsc();
 
 	__asm__ __volatile__(
 	"				# arch_write_unlock	\n"

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