On Wed, Aug 21, 2013 at 10:16:02AM +0200, Paolo Bonzini wrote:
> Il 21/08/2013 04:02, Asias He ha scritto:
> > In block/gluster.c, we have
> >
> > gluster_finish_aiocb
> > {
> > if (retval != sizeof(acb)) {
> > qemu_mutex_lock_iothread(); /* We are in gluster thread context */
> > ...
> > qemu_mutex_unlock_iothread();
> > }
> > }
> >
> > qemu tools, e.g. qemu-img, might race here because
> > qemu_mutex_{lock,unlock}_iothread are a nop operation and
> > gluster_finish_aiocb is in the gluster thread context.
> >
> > To fix, we introduce our own mutex for qemu tools.
> >
> > Signed-off-by: Asias He <as...@redhat.com>
> > ---
> > stubs/iothread-lock.c | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/stubs/iothread-lock.c b/stubs/iothread-lock.c
> > index 5d8aca1..d5c6dec 100644
> > --- a/stubs/iothread-lock.c
> > +++ b/stubs/iothread-lock.c
> > @@ -1,10 +1,21 @@
> > #include "qemu-common.h"
> > #include "qemu/main-loop.h"
> >
> > +static QemuMutex qemu_tools_mutex;
> > +static pthread_once_t qemu_tools_once = PTHREAD_ONCE_INIT;
>
> Doesn't work on Windows, but you can just add
Hmm, Any reasons, why it does not work on Windows?
> __attribute__((__constructor__)) to qemu_tools_mutex_init.
__attribute__((__constructor__)) works on Windows?
> Paolo
>
> > +static void qemu_tools_mutex_init(void)
> > +{
> > + qemu_mutex_init(&qemu_tools_mutex);
> > +}
> > +
> > void qemu_mutex_lock_iothread(void)
> > {
> > + pthread_once(&qemu_tools_once, qemu_tools_mutex_init);
> > + qemu_mutex_lock(&qemu_tools_mutex);
> > }
> >
> > void qemu_mutex_unlock_iothread(void)
> > {
> > + qemu_mutex_unlock(&qemu_tools_mutex);
> > }
> >
>
--
Asias
