On 03/01/2010 10:33 PM, Aurelien Jarno wrote:
> While trying to implement setcond on TCG ARM, I have discovered it does
> not work anymore. I have bisected this regression to:
>
> commit 6113d6d3169393c323ac4c82d756a850145a5e7a
> Author: Paolo Bonzini<pbonzini@redhat.com>
> Date:   Fri Jan 15 09:42:09 2010 +0100
>
>      change while to if
>
>      The while loop will be executed exactly 0 or 1 times, depending on
>      env->exit_request.
>
>      Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
>      Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>
>
> The assertion is actually triggered. When the next patch removing the
> assertion is also applied it segfaults instead.

Looks like a race.  The only piece of logic that is changed by that 
commit is reverted in the attached patch, can you try it?  If it passes, 
I can resubmit with S-o-b.

If it doesn't pass, I wonder whether the while loop was there to trick 
the compiler into not optimizing something.  Seems a bit too clever though.

Paolo