From: Nick Piggin <npiggin@suse.de>
Date: Thu, 23 Mar 2006 11:01:02 +0000 (-0800)
Subject: [PATCH] atomic: add_unless cmpxchg optimise
X-Git-Tag: v2.6.17-rc1~1006
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0b2fcfdb8b4e7e379192f24ea2203163ddf5df1d;p=pandora-kernel.git

[PATCH] atomic: add_unless cmpxchg optimise

Without branch hints, the very unlikely chance of the loop repeating due to
cmpxchg failure is unrolled with gcc-4 that I have tested.

Improve this for architectures with a native cas/cmpxchg.  llsc archs
should try to implement this natively.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Andi Kleen <ak@muc.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

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