From: Christoph Lameter Date: Wed, 1 Jun 2011 17:25:47 +0000 (-0500) Subject: x86: Add support for cmpxchg_double X-Git-Tag: v3.1-rc1~278^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3824abd1279ef75f791c43a6b1e3162ae0692b42;p=pandora-kernel.git x86: Add support for cmpxchg_double A simple implementation that only supports the word size and does not have a fallback mode (would require a spinlock). Add 32 and 64 bit support for cmpxchg_double. cmpxchg double uses the cmpxchg8b or cmpxchg16b instruction on x86 processors to compare and swap 2 machine words. This allows lockless algorithms to move more context information through critical sections. Set a flag CONFIG_CMPXCHG_DOUBLE to signal that support for double word cmpxchg detection has been build into the kernel. Note that each subsystem using cmpxchg_double has to implement a fall back mechanism as long as we offer support for processors that do not implement cmpxchg_double. Reviewed-by: H. Peter Anvin Cc: Tejun Heo Cc: Pekka Enberg Signed-off-by: Christoph Lameter Link: http://lkml.kernel.org/r/20110601172614.173427964@linux.com Signed-off-by: H. Peter Anvin --- Reading git-diff-tree failed