Remove unnecessary cast in prefetch()
commit4ecbca8554d0f643351ee07d3284138a5e85ba81
authorSerge Belyshev <belyshev@depni.sinp.msu.ru>
Thu, 4 Oct 2007 21:10:04 +0000 (4 23:10 +0200)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Fri, 5 Oct 2007 15:04:35 +0000 (5 08:04 -0700)
tree06fd712d440bba74c7957736a9a804dd42e276a4
parent9cdcaa2c9330432bfe891d40f2d914b80bbcf9f3
Remove unnecessary cast in prefetch()

It is ok to call prefetch() function with NULL argument, as specifically
commented in include/linux/prefetch.h.  But in standard C, it is invalid
to dereference NULL pointer (see C99 standard 6.5.3.2 paragraph 4 and
note #84).

prefetch() has a memory reference for its argument.

Newer gcc versions (4.3 and above) will use that to conclude that "x"
argument is non-null and thus wreaking havok everywhere prefetch() was
inlined.

Fixed by removing cast and changing asm constraint.

[ It seems in theory gcc 4.2 could miscompile this too; although no
  cases known.  In 2.6.24 we should probably switch to
  __builtin_prefetch() instead, but this is a simpler fix for now.
-- AK ]

Signed-off-by: Serge Belyshev <belyshev@depni.sinp.msu.ru>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/asm-x86_64/processor.h