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

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Message-ID: <20210117052810-mutt-send-email-mst@kernel.org>
Date:   Sun, 17 Jan 2021 05:30:01 -0500
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, elic@...dia.com
Subject: Re: [PATCH V2] mlx5: vdpa: fix possible uninitialized var

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@...hat.com>

Of course if it's actually something else this is not DTRT ...
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;


> ---
>  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