Re: [PATCH V2] mlx5: vdpa: fix possible uninitialized var

[Jason Wang]

On 2021/1/17 下午6:30, Michael S. Tsirkin wrote:
> On Thu, Jan 14, 2021 at 03:09:04PM +0800, Jason Wang wrote:
> > When compiling with -Werror=maybe-uninitialized, gcc may complains the
> > possible uninitialized umem. Since the callers won't pass value other
> > than 1 to 3, making 3 as default to fix the compiler warning.
> >
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> Of course if it's actually something else this is not DTRT ...


It breaks some donw stream build (which mandates 
-Werror=maybe-uninitialized)


> As long as we worry about this warning, let's have defence in depth:
>    	case 3:
>    		umem = &mvq->umem3;
>    		break;
>   +	default:
>   +		umem = NULL;
>   +              BUG();
>   +		break;


Checkpatch doesn't like this:

WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code 
rather than BUG() or BUG_ON()
#20: FILE: drivers/vdpa/mlx5/net/mlx5_vnet.c:695:
+        BUG();

But if you stick, I can go this way.

Thanks


> > ---
> >   drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index f1d54814db97..07ccc61cd6f6 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -703,7 +703,7 @@ static void umem_destroy(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue
> >   	case 2:
> >   		umem = &mvq->umem2;
> >   		break;
> > -	case 3:
> > +	default:
> >   		umem = &mvq->umem3;
> >   		break;
> >   	}
> > --
> > 2.25.1