linux-kernel - Re: [PATCH] vdpa/mlx5: fix error handling in mlx5_vdpa_dev

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Message-ID: <3740be2d-192f-aeaf-02fe-e309cdb278dc@oracle.com>
Date:   Fri, 7 Jan 2022 17:49:42 -0800
From:   Si-Wei Liu <si-wei.liu@...cle.com>
To:     trix@...hat.com, mst@...hat.com, jasowang@...hat.com,
        nathan@...nel.org, ndesaulniers@...gle.com, elic@...dia.com,
        parav@...dia.com, xieyongji@...edance.com
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] vdpa/mlx5: fix error handling in mlx5_vdpa_dev_add()


The proposed fix looks fine, but I still hope this to revert this series 
if at all possible. The review hadn't been done yet.

On 1/7/2022 1:13 PM, trix@...hat.com wrote:
> From: Tom Rix <trix@...hat.com>
>
> Clang build fails with
> mlx5_vnet.c:2574:6: error: variable 'mvdev' is used uninitialized whenever
>    'if' condition is true
>          if (!ndev->vqs || !ndev->event_cbs) {
>              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> mlx5_vnet.c:2660:14: note: uninitialized use occurs here
>          put_device(&mvdev->vdev.dev);
>                      ^~~~~
> This because mvdev is set after trying to allocate ndev->vqs,event_cbs.
> So move the allocation to after mvdev is set but before the arrays
> are used in init_mvqs()
>
> Fixes: 7620d51af29a ("vdpa/mlx5: Support configuring max data virtqueue")
> Signed-off-by: Tom Rix <trix@...hat.com>

Reviewed-by: Si-Wei Liu<si-wei.liu@...cle.com>
> ---
>   drivers/vdpa/mlx5/net/mlx5_vnet.c | 10 ++++++----
>   1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index b564c70475815..37220f6db7ad7 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2569,16 +2569,18 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>   	if (IS_ERR(ndev))
>   		return PTR_ERR(ndev);
>   
> +	ndev->mvdev.mlx_features = mgtdev->mgtdev.supported_features;
> +	ndev->mvdev.max_vqs = max_vqs;
> +	mvdev = &ndev->mvdev;
> +	mvdev->mdev = mdev;
> +
>   	ndev->vqs = kcalloc(max_vqs, sizeof(*ndev->vqs), GFP_KERNEL);
>   	ndev->event_cbs = kcalloc(max_vqs + 1, sizeof(*ndev->event_cbs), GFP_KERNEL);
>   	if (!ndev->vqs || !ndev->event_cbs) {
>   		err = -ENOMEM;
>   		goto err_alloc;
>   	}
> -	ndev->mvdev.mlx_features = mgtdev->mgtdev.supported_features;
> -	ndev->mvdev.max_vqs = max_vqs;
> -	mvdev = &ndev->mvdev;
> -	mvdev->mdev = mdev;
> +
>   	init_mvqs(ndev);
>   	mutex_init(&ndev->reslock);
>   	config = &ndev->config;