Re: [Qemu-devel] [PATCH v2 3/5] libvhost-user: quit when no more data received

[Marc-André Lureau]

Hi

On Tue, Aug 8, 2017 at 10:52 PM Jens Freimann <address@hidden> wrote:
>
> From: Jens Freimann <address@hidden>
>
> End processing of messages when VHOST_USER_NONE
> is received.
>
> Without this we run into a vubr_panic() call and get
> "PANIC: Unhandled request: 0"
>
> Signed-off-by: Jens Freimann <address@hidden>
> ---
>  contrib/libvhost-user/libvhost-user.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/contrib/libvhost-user/libvhost-user.c 
> b/contrib/libvhost-user/libvhost-user.c
> index 9efb9dac0e..35fa0c5e56 100644
> --- a/contrib/libvhost-user/libvhost-user.c
> +++ b/contrib/libvhost-user/libvhost-user.c
> @@ -161,7 +161,7 @@ vu_message_read(VuDev *dev, int conn_fd, VhostUserMsg 
> *vmsg)
>          rc = recvmsg(conn_fd, &msg, 0);
>      } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
>
> -    if (rc <= 0) {
> +    if (rc < 0) {
>          vu_panic(dev, "Error while recvmsg: %s", strerror(errno));
>          return false;
>      }
> @@ -806,6 +806,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
>          return vu_get_queue_num_exec(dev, vmsg);
>      case VHOST_USER_SET_VRING_ENABLE:
>          return vu_set_vring_enable_exec(dev, vmsg);
> +    case VHOST_USER_NONE:
> +        break;


I am afraid this isn't working. vu_message_read() returns
true/success, vu_process_message() returns false/no-reply, so
vu_dispatch() will return success, and the caller has no clear way to
know that the socket got disconnected. For me the vu_panic() was quite
more appropriate here.

What problem did this patch exactly solve?

>
>      default:
>          vmsg_close_fds(vmsg);
>          vu_panic(dev, "Unhandled request: %d", vmsg->request);
> --
> 2.13.3
>
>