From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/4] ARM: atomic ops: reduce critical region in atomic64_cmpxchg
Date: Wed, 30 Jun 2010 15:04:46 +0100 [thread overview]
Message-ID: <1277906688-12065-3-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1277906688-12065-2-git-send-email-will.deacon@arm.com>
In order to reduce the likelihood of failure in a load/store
exclusive block, the number of intervening instructions should
be kept to a minimum.
This patch hoists a mov operation out of the critical region
in atomic64_cmpxchg.
Cc: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/include/asm/atomic.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
index e9e56c0..4f0f282 100644
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -358,8 +358,8 @@ static inline u64 atomic64_cmpxchg(atomic64_t *ptr, u64 old, u64 new)
do {
__asm__ __volatile__("@ atomic64_cmpxchg\n"
- "ldrexd %1, %H1, [%2]\n"
"mov %0, #0\n"
+ "ldrexd %1, %H1, [%2]\n"
"teq %1, %3\n"
"teqeq %H1, %H3\n"
"strexdeq %0, %4, %H4, [%2]"
--
1.6.3.3
next prev parent reply other threads:[~2010-06-30 14:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-30 14:04 [PATCH 0/4] Fix atomic operations so that atomic64_test passes on ARM [V2] Will Deacon
2010-06-30 14:04 ` [PATCH 1/4] ARM: atomic ops: fix register constraints for atomic64_add_unless Will Deacon
2010-06-30 14:04 ` Will Deacon [this message]
2010-06-30 14:04 ` [PATCH 3/4] ARM: atomic ops: add memory constraints to inline asm Will Deacon
2010-06-30 14:04 ` [PATCH 4/4] ARM: atomic64_test: add ARM as supported architecture Will Deacon
2010-07-08 5:50 ` Nicolas Pitre
2010-07-07 16:42 ` [PATCH 3/4] ARM: atomic ops: add memory constraints to inline asm Will Deacon
2010-07-08 5:49 ` Nicolas Pitre
2010-07-08 9:36 ` Will Deacon
[not found] ` <004b01cb1e81$0b745960$225d0c20$%deacon@arm.com>
2010-07-08 12:42 ` Nicolas Pitre
[not found] ` <004101cb1df3$5825ecd0$0871c670$%deacon@arm.com>
2010-07-08 5:58 ` Nicolas Pitre
2010-07-08 10:03 ` Will Deacon
2010-07-08 4:49 ` [PATCH 2/4] ARM: atomic ops: reduce critical region in atomic64_cmpxchg Nicolas Pitre
2010-07-08 9:43 ` Will Deacon
2010-07-08 4:37 ` [PATCH 1/4] ARM: atomic ops: fix register constraints for atomic64_add_unless Nicolas Pitre
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