On Wed, 19 Jun 2024 10:55:29 +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 <lirongqing@xxxxxxxxx>
> ---
> 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));
Did you by any chance use an automated tool of any sort to find this
issue or generate the fix?
I don't think this is actually necessary here, you're in the same
context as the updater of the stats, you don't need any protection.
You can remove u64_stats_update_begin() / end() (in net-next, there's
no bug).
I won't comment on implications of calling dim_update_sample() in
a loop.
Please make sure you answer my "did you use a tool" question, I'm
really curious.
--
pw-bot: cr
