Re: [Qemu-devel] [PATCH v2 2/3] block/iscsi: take iscsilun->mutex in iscsi_timed_check_events()

[Paolo Bonzini <pbonzini@redhat.com>]

On 03/02/2018 07:16, Stefan Hajnoczi wrote:
> Commit d045c466d9e62b4321fadf586d024d54ddfd8bd4 ("iscsi: do not use
> aio_context_acquire/release") introduced iscsilun->mutex but appears to
> have overlooked iscsi_timed_check_events() when introducing the mutex.
> 
> iscsi_service() and iscsi_set_events() must be called with
> iscsilun->mutex held.
> 
> iscsi_timed_check_events() is invoked from the AioContext and does not
> take the mutex.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

> ---
>  block/iscsi.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index cd0738942c..1cfe1c647c 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -339,6 +339,8 @@ static void iscsi_timed_check_events(void *opaque)
>  {
>      IscsiLun *iscsilun = opaque;
>  
> +    qemu_mutex_lock(&iscsilun->mutex);
> +
>      /* check for timed out requests */
>      iscsi_service(iscsilun->iscsi, 0);
>  
> @@ -351,6 +353,8 @@ static void iscsi_timed_check_events(void *opaque)
>       * to return to service once this situation changes. */
>      iscsi_set_events(iscsilun);
>  
> +    qemu_mutex_unlock(&iscsilun->mutex);
> +
>      timer_mod(iscsilun->event_timer,
>                qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + EVENT_INTERVAL);
>  }
>