[Qemu-devel] Re: [PATCH] qemu: work around for "posix-aio-compat"

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 21, 2009 at 05:42:34PM +0200, Michael S. Tsirkin wrote:
> On Tue, Oct 20, 2009 at 08:57:13PM +0200, Paolo Bonzini wrote:
> > On 10/20/2009 08:39 PM, Mark McLoughlin wrote:
> >> On Thu, 2009-10-08 at 22:37 +0200, Michael S. Tsirkin wrote:
> >>> With commit ee3993069ff55fa6f1c64daf1e09963e340db8e4,
> >>> "posix-aio-compat: avoid signal race when spawning a thread"
> >>> winxp installation on a raw format file fails
> >>> during disk format, with a message "your
> >>> disk may be damaged".
> >>>
> >>> This commit moved signal mask from aio thread to creating thread.
> >>> It turns out if we keep the mask in aio thread as well, the problem
> >>> disappears. It should not be needed, but since this is harmless, let's
> >>> keep it around until someone inclined to debug pthread library internals
> >>> can check this issue.
> >>>
> >>> While we are at it, convert sigprocmask to pthread_sigmask
> >>> as per posix.
> >>
> >> FWIW, I just started hitting a boot hang with qemu.git and --enable-kvm
> >> on a Fedora 11 machine with a Fedora 11 guest.
> >>
> >> I bisected it back to malc's commit, found this thread, applied
> >> Michael's patch and confirmed that it fixes the problem for me too.
> >
> > If anybody can send me the output of compiling the "strange" file with  
> > and without the patch, both with "-fdump-tree-all -fdump-rtl-all -O2  
> > --save-temps -g" flags, I could try debugging it in GCC.
> >
> > It will be huge, so bz/gz/lzip it.
> 
> I've uploaded them here:
> http://www.kernel.org/pub/linux/kernel/people/mst/
> you can't see them in mirrors yet but will be able to soon when
> kernel.org mirroring system catches them.

ok, it's there now:
http://www.kernel.org/pub/linux/kernel/people/mst/posix-aio-corruption.tbz2
once you open this, you will see subdirectories "hang" and "nohang".
the source file is also there, so that you can compare.

> 
> > Paolo