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
__attribute__((__constructor__)) to qemu_tools_mutex_init.
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);
> }
>
