Re: [PATCH net v3 1/2] virtio_net: fix possible dim status unrecoverable

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, May 28, 2024 at 09:41:15PM +0800, Heng Qi wrote:
> When the dim worker is scheduled, if it no longer needs to issue
> commands, dim may not be able to return to the working state later.
> 
> For example, the following single queue scenario:
>   1. The dim worker of rxq0 is scheduled, and the dim status is
>      changed to DIM_APPLY_NEW_PROFILE;
>   2. dim is disabled or parameters have not been modified;
>   3. virtnet_rx_dim_work exits directly;
> 
> Then, even if net_dim is invoked again, it cannot work because the
> state is not restored to DIM_START_MEASURE.
> 
> Fixes: 6208799553a8 ("virtio-net: support rx netdim")
> Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>


Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  drivers/net/virtio_net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 4a802c0ea2cb..4f828a9e5889 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -4417,9 +4417,9 @@ static void virtnet_rx_dim_work(struct work_struct *work)
>  		if (err)
>  			pr_debug("%s: Failed to send dim parameters on rxq%d\n",
>  				 dev->name, qnum);
> -		dim->state = DIM_START_MEASURE;
>  	}
>  out:
> +	dim->state = DIM_START_MEASURE;
>  	mutex_unlock(&rq->dim_lock);
>  }
>  
> -- 
> 2.32.0.3.g01195cf9f