Re: [Qemu-devel] [PATCH] virtio-blk: Move resetting of req->mr_next to virtio_blk_handle_rw_error

[Paolo Bonzini <pbonzini@redhat.com>]

On 23/11/2015 01:41, Fam Zheng wrote:
> "werror=report" would free the req in virtio_blk_handle_rw_error, we
> mustn't write to it in that case.
> 
> Reported-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  hw/block/virtio-blk.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 848f3fe..756ae5c 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -72,6 +72,9 @@ static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
>      VirtIOBlock *s = req->dev;
>  
>      if (action == BLOCK_ERROR_ACTION_STOP) {
> +        /* Break the link as the next request is going to be parsed from the
> +         * ring again. Otherwise we may end up doing a double completion! */
> +        req->mr_next = NULL;
>          req->next = s->rq;
>          s->rq = req;
>      } else if (action == BLOCK_ERROR_ACTION_REPORT) {
> @@ -112,10 +115,6 @@ static void virtio_blk_rw_complete(void *opaque, int ret)
>               * happen on the other side of the migration).
>               */
>              if (virtio_blk_handle_rw_error(req, -ret, is_read)) {
> -                /* Break the link in case the next request is added to the
> -                 * restart queue and is going to be parsed from the ring again.
> -                 */
> -                req->mr_next = NULL;
>                  continue;
>              }
>          }
> 

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