Re: [PATCH 1/6] vdpa: fix improper error message when adding vdpa dev

[Eli Cohen]

On 30/01/2023 22:30, Si-Wei Liu wrote:
> In below example, before the fix, mtu attribute is supported
> by the parent mgmtdev, but the error message showing "All
> provided are not supported" is just misleading.
>
> $ vdpa mgmtdev show
> vdpasim_net:
>    supported_classes net
>    max_supported_vqs 3
>    dev_features MTU MAC CTRL_VQ CTRL_MAC_ADDR ANY_LAYOUT VERSION_1 ACCESS_PLATFORM
>
> $ vdpa dev add mgmtdev vdpasim_net name vdpasim0 mtu 5000 max_vqp 2
> Error: vdpa: All provided attributes are not supported.
> kernel answers: Operation not supported
>
> After fix, the relevant error message will be like:
>
> $ vdpa dev add mgmtdev vdpasim_net name vdpasim0 mtu 5000 max_vqp 2
> Error: vdpa: Some provided attributes are not supported.
> kernel answers: Operation not supported
>
> $ vdpa dev add mgmtdev vdpasim_net name vdpasim0 max_vqp 2
> Error: vdpa: All provided attributes are not supported.
> kernel answers: Operation not supported
>
> Signed-off-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
> Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
>   drivers/vdpa/vdpa.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 8ef7aa1..5e57935 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -622,13 +622,20 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i
>   		err = PTR_ERR(mdev);
>   		goto err;
>   	}
> -	if ((config.mask & mdev->config_attr_mask) != config.mask) {
> +	if (config.mask && (config.mask & mdev->config_attr_mask) == 0) {
If config.mask is zero than the condition is false even without the 
change so I don't see why is this change needed.
>   		NL_SET_ERR_MSG_MOD(info->extack,
>   				   "All provided attributes are not supported");
>   		err = -EOPNOTSUPP;
>   		goto err;
>   	}
>   
> +	if ((config.mask & mdev->config_attr_mask) != config.mask) {
> +		NL_SET_ERR_MSG_MOD(info->extack,
> +				   "Some provided attributes are not supported");
Changing the message is needed but maybe list the attributes that were 
specified but are not supported?
> +		err = -EOPNOTSUPP;
> +		goto err;
> +	}
> +
>   	err = mdev->ops->dev_add(mdev, name, &config);
>   err:
>   	up_write(&vdpa_dev_lock);