Re: [PATCH] vdpa: fix gcc cvq_isolated uninitialized variable warning

[Eugenio Perez Martin]

On Mon, Sep 11, 2023 at 11:54 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
>
> gcc 13.2.1 emits the following warning:
>
>   net/vhost-vdpa.c: In function ‘net_vhost_vdpa_init.constprop’:
>   net/vhost-vdpa.c:1394:25: error: ‘cvq_isolated’ may be used uninitialized 
> [-Werror=maybe-uninitialized]
>    1394 |         s->cvq_isolated = cvq_isolated;
>         |         ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
>   net/vhost-vdpa.c:1355:9: note: ‘cvq_isolated’ was declared here
>    1355 |     int cvq_isolated;
>         |         ^~~~~~~~~~~~
>   cc1: all warnings being treated as errors
>

I think GCC is evaluating the case where (queue_pair_index == 0 &&
!is_datapath), which should be not possible.

If it is useful we can refactor the conditionals so we don't need the
variable at that level of the function. If not,

Acked-by: Eugenio Pérez <eperezma@redhat.com>

Thanks!

> Cc: Eugenio Pérez <eperezma@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  net/vhost-vdpa.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 34202ca009..7eaee841aa 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -1352,7 +1352,7 @@ static NetClientState 
> *net_vhost_vdpa_init(NetClientState *peer,
>      VhostVDPAState *s;
>      int ret = 0;
>      assert(name);
> -    int cvq_isolated;
> +    int cvq_isolated = 0;
>
>      if (is_datapath) {
>          nc = qemu_new_net_client(&net_vhost_vdpa_info, peer, device,
> --
> 2.41.0
>