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 <jasow...@redhat.com>
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

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