Subject: Re: [PATCH] virtio_net: Use u64_stats_fetch_begin() for stats fetch

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 9 Jul 2024 08:45:18 -0400

On Wed, Jun 19, 2024 at 10:55:29AM +0800, Li RongQing wrote:
> This place is fetching the stats, so u64_stats_fetch_begin
> and u64_stats_fetch_retry should be used
> 
> Fixes: 6208799553a8 ("virtio-net: support rx netdim")
> Signed-off-by: Li RongQing <[email-masked]>

So I dropped this from my tree, if you think it's
still necessary, pls resubmit to net-next.

Thanks!

> ---
>  drivers/net/virtio_net.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 61a57d1..b669e73 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2332,16 +2332,18 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
>  static void virtnet_rx_dim_update(struct virtnet_info *vi, struct receive_queue *rq)
>  {
>  	struct dim_sample cur_sample = {};
> +	unsigned int start;
>  
>  	if (!rq->packets_in_napi)
>  		return;
>  
> -	u64_stats_update_begin(&rq->stats.syncp);
> -	dim_update_sample(rq->calls,
> -			  u64_stats_read(&rq->stats.packets),
> -			  u64_stats_read(&rq->stats.bytes),
> -			  &cur_sample);
> -	u64_stats_update_end(&rq->stats.syncp);
> +	do {
> +		start = u64_stats_fetch_begin(&rq->stats.syncp);
> +		dim_update_sample(rq->calls,
> +				u64_stats_read(&rq->stats.packets),
> +				u64_stats_read(&rq->stats.bytes),
> +				&cur_sample);
> +	} while (u64_stats_fetch_retry(&rq->stats.syncp, start));
>  
>  	net_dim(&rq->dim, cur_sample);
>  	rq->packets_in_napi = 0;
> -- 
> 2.9.4