On 12/8/25 22:34, Bui Quang Minh wrote:
Calling napi_disable() on an already disabled napi can cause the deadlock. In commit 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx"), to avoid the deadlock, when pausing the RX in virtnet_rx_pause[_all](), we disable and cancel the delayed refill work. However, in the virtnet_rx_resume_all(), we enable the delayed refill work too early before enabling all the receive queue napis.The deadlock can be reproduced by running selftests/drivers/net/hw/xsk_reconfig.py with multiqueue virtio-net device and inserting a cond_resched() inside the for loop in virtnet_rx_resume_all() to increase the success rate. Because the worker processing the delayed refilled work runs on the same CPU as virtnet_rx_resume_all(), a reschedule is needed to cause the deadlock. In real scenario, the contention on netdev_lock can cause the reschedule. This fixes the deadlock by ensuring all receive queue's napis are enabled before we enable the delayed refill work in virtnet_rx_resume_all() and virtnet_open(). Fixes: 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx") Reported-by: Paolo Abeni <[email protected]> Closes: https://netdev-ctrl.bots.linux.dev/logs/vmksft/drv-hw-dbg/results/400961/3-xdp-py/stderr Signed-off-by: Bui Quang Minh <[email protected]>
I forgot to add Cc:[email protected]. I will add in next version. Thanks, Quang Minh.
--- drivers/net/virtio_net.c | 59 +++++++++++++++++++--------------------- 1 file changed, 28 insertions(+), 31 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 8e04adb57f52..f2b1ea65767d 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2858,6 +2858,20 @@ static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq, return err != -ENOMEM; }+static void virtnet_rx_refill_all(struct virtnet_info *vi)+{ + bool schedule_refill = false; + int i; + + enable_delayed_refill(vi); + for (i = 0; i < vi->curr_queue_pairs; i++) + if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) + schedule_refill = true; + + if (schedule_refill) + schedule_delayed_work(&vi->refill, 0); +} + static void skb_recv_done(struct virtqueue *rvq) { struct virtnet_info *vi = rvq->vdev->priv; @@ -3216,19 +3230,14 @@ static int virtnet_open(struct net_device *dev) struct virtnet_info *vi = netdev_priv(dev); int i, err;- enable_delayed_refill(vi);- for (i = 0; i < vi->max_queue_pairs; i++) { - if (i < vi->curr_queue_pairs) - /* Make sure we have some buffers: if oom use wq. */ - if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) - schedule_delayed_work(&vi->refill, 0); - err = virtnet_enable_queue_pair(vi, i); if (err < 0) goto err_enable_qp; }+ virtnet_rx_refill_all(vi);+ if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) { if (vi->status & VIRTIO_NET_S_LINK_UP) netif_carrier_on(vi->dev); @@ -3463,39 +3472,27 @@ static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue *rq) __virtnet_rx_pause(vi, rq); }-static void __virtnet_rx_resume(struct virtnet_info *vi,- struct receive_queue *rq, - bool refill) -{ - bool running = netif_running(vi->dev); - bool schedule_refill = false; - - if (refill && !try_fill_recv(vi, rq, GFP_KERNEL)) - schedule_refill = true; - if (running) - virtnet_napi_enable(rq); - - if (schedule_refill) - schedule_delayed_work(&vi->refill, 0); -} - static void virtnet_rx_resume_all(struct virtnet_info *vi) { int i;- enable_delayed_refill(vi);- for (i = 0; i < vi->max_queue_pairs; i++) { - if (i < vi->curr_queue_pairs) - __virtnet_rx_resume(vi, &vi->rq[i], true); - else - __virtnet_rx_resume(vi, &vi->rq[i], false); + if (netif_running(vi->dev)) { + for (i = 0; i < vi->max_queue_pairs; i++) + virtnet_napi_enable(&vi->rq[i]); + + virtnet_rx_refill_all(vi); } }static void virtnet_rx_resume(struct virtnet_info *vi, struct receive_queue *rq){ - enable_delayed_refill(vi); - __virtnet_rx_resume(vi, rq, true); + if (netif_running(vi->dev)) { + virtnet_napi_enable(rq); + + enable_delayed_refill(vi); + if (!try_fill_recv(vi, rq, GFP_KERNEL)) + schedule_delayed_work(&vi->refill, 0); + } }static int virtnet_rx_resize(struct virtnet_info *vi,
