On 4/2/25 7:42 AM, Bui Quang Minh wrote:
> When setting up XDP for a running interface, we call napi_disable() on
> the receive queue's napi. In delayed refill_work, it also calls
> napi_disable() on the receive queue's napi. This can leads to deadlock
> when napi_disable() is called on an already disabled napi. This commit
> fixes this by disabling future and cancelling all inflight delayed
> refill works before calling napi_disabled() in virtnet_xdp_set.
>
> Fixes: 4941d472bf95 ("virtio-net: do not reset during XDP set")
> Signed-off-by: Bui Quang Minh <minhquangbui99@xxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7e4617216a4b..33406d59efe2 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -5956,6 +5956,15 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
> if (!prog && !old_prog)
> return 0;
>
> + /*
> + * Make sure refill_work does not run concurrently to
> + * avoid napi_disable race which leads to deadlock.
> + */
> + if (netif_running(dev)) {
> + disable_delayed_refill(vi);
> + cancel_delayed_work_sync(&vi->refill);
AFAICS at this point refill_work() could still be running, why don't you
need to call flush_delayed_work()?
@Jason: somewhat related, why virtnet_close() does not use
flush_delayed_work(), too?
Thanks,
Paolo
