compiler/gcc4: Make quirk for asm_volatile_goto() unconditional
authorSteven Noonan <steven@uplinklabs.net>
Thu, 13 Feb 2014 07:01:07 +0000 (23:01 -0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 22 Feb 2014 21:32:29 +0000 (13:32 -0800)
commita6ad68bc9fd3159cfb3495d4f96b2d20bb625fad
treed9c6adae2356be943d6108f857834e7d7dead258
parent1f25819485fdaee53cc5b8ec96a44a440a63cf46
compiler/gcc4: Make quirk for asm_volatile_goto() unconditional

commit a9f180345f5378ac87d80ed0bea55ba421d83859 upstream.

I started noticing problems with KVM guest destruction on Linux
3.12+, where guest memory wasn't being cleaned up. I bisected it
down to the commit introducing the new 'asm goto'-based atomics,
and found this quirk was later applied to those.

Unfortunately, even with GCC 4.8.2 (which ostensibly fixed the
known 'asm goto' bug) I am still getting some kind of
miscompilation. If I enable the asm_volatile_goto quirk for my
compiler, KVM guests are destroyed correctly and the memory is
cleaned up.

So make the quirk unconditional for now, until bug is found
and fixed.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/1392274867-15236-1-git-send-email-steven@uplinklabs.net
Link: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
include/linux/compiler-gcc4.h