On Tue, 2024-04-23 at 06:57 +0300, Daniel Jurgens wrote:
> Once the RTNL locking around the control buffer is removed there can be
> contention on the per queue RX interrupt coalescing data. Use a mutex
> per queue. A mutex is required because virtnet_send_command can sleep.
>
> Signed-off-by: Daniel Jurgens <danielj@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 53 +++++++++++++++++++++++++++++++---------
> 1 file changed, 41 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index af9048ddc3c1..033e1d6ea31b 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -184,6 +184,9 @@ struct receive_queue {
> /* Is dynamic interrupt moderation enabled? */
> bool dim_enabled;
>
> + /* Used to protect dim_enabled and inter_coal */
> + struct mutex dim_lock;
> +
> /* Dynamic Interrupt Moderation */
> struct dim dim;
>
> @@ -2218,6 +2221,10 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
> /* Out of packets? */
> if (received < budget) {
> napi_complete = virtqueue_napi_complete(napi, rq->vq, received);
> + /* Intentionally not taking dim_lock here. This could result
> + * in a net_dim call with dim now disabled. But virtnet_rx_dim_work
> + * will take the lock not update settings if dim is now disabled.
Minor nit: the above comment looks confusing/mangled to me ?!?
will take the lock and will not update settings...
Thanks,
Paolo
