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Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Bui Quang Minh Subject: [PATCH net] virtio-net: enable all napis before scheduling refill work Date: Mon, 8 Dec 2025 22:34:19 +0700 Message-ID: <20251208153419.18196-1-minhquangbui99@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Closes: https://netdev-ctrl.bots.linux.dev/logs/vmksft/drv-hw-dbg/results/400961/3-xdp-py/stderr Signed-off-by: Bui 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, -- 2.43.0