* [PATCH V2] mlx5: vdpa: fix possible uninitialized var
@ 2021-01-14 7:09 Jason Wang
2021-01-17 10:30 ` Michael S. Tsirkin
0 siblings, 1 reply; 3+ messages in thread
From: Jason Wang @ 2021-01-14 7:09 UTC (permalink / raw)
To: mst, jasowang, virtualization, linux-kernel; +Cc: elic
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@redhat.com>
---
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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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH V2] mlx5: vdpa: fix possible uninitialized var
2021-01-14 7:09 [PATCH V2] mlx5: vdpa: fix possible uninitialized var Jason Wang
@ 2021-01-17 10:30 ` Michael S. Tsirkin
2021-01-18 5:32 ` Jason Wang
0 siblings, 1 reply; 3+ messages in thread
From: Michael S. Tsirkin @ 2021-01-17 10:30 UTC (permalink / raw)
To: Jason Wang; +Cc: elic, linux-kernel, virtualization
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@redhat.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
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH V2] mlx5: vdpa: fix possible uninitialized var
2021-01-17 10:30 ` Michael S. Tsirkin
@ 2021-01-18 5:32 ` Jason Wang
0 siblings, 0 replies; 3+ messages in thread
From: Jason Wang @ 2021-01-18 5:32 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: elic, linux-kernel, virtualization
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@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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2021-01-17 10:30 ` Michael S. Tsirkin
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