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Tsirkin" , Jason Wang , Xuan Zhuo , Andrew Lunn , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , "David S . Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Bui Quang Minh Subject: [PATCH v2 1/3] virtio-net: disable delayed refill when pausing rx Date: Mon, 14 Apr 2025 12:08:35 +0700 Message-ID: <20250414050837.31213-2-minhquangbui99@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250414050837.31213-1-minhquangbui99@gmail.com> References: <20250414050837.31213-1-minhquangbui99@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When pausing rx (e.g. set up xdp, xsk pool, rx resize), 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. When napi_disable() is called on an already disabled napi, it will sleep in napi_disable_locked while still holding the netdev_lock. As a result, later napi_enable gets stuck too as it cannot acquire the netdev_lock. This leads to refill_work and the pause-then-resume tx are stuck altogether. This scenario can be reproducible by binding a XDP socket to virtio-net interface without setting up the fill ring. As a result, try_fill_recv will fail until the fill ring is set up and refill_work is scheduled. This commit adds virtnet_rx_(pause/resume)_all helpers and fixes up the virtnet_rx_resume to disable future and cancel all inflights delayed refill_work before calling napi_disable() to pause the rx. Fixes: 413f0271f396 ("net: protect NAPI enablement with netdev_lock()") Signed-off-by: Bui Quang Minh --- drivers/net/virtio_net.c | 60 ++++++++++++++++++++++++++++++++++------ 1 file changed, 51 insertions(+), 9 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 7e4617216a4b..4361b91ccc64 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3342,10 +3342,53 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, = struct net_device *dev) return NETDEV_TX_OK; } =20 +static void virtnet_rx_pause_all(struct virtnet_info *vi) +{ + bool running =3D netif_running(vi->dev); + + /* + * Make sure refill_work does not run concurrently to + * avoid napi_disable race which leads to deadlock. + */ + disable_delayed_refill(vi); + cancel_delayed_work_sync(&vi->refill); + if (running) { + int i; + + for (i =3D 0; i < vi->max_queue_pairs; i++) { + virtnet_napi_disable(&vi->rq[i]); + virtnet_cancel_dim(vi, &vi->rq[i].dim); + } + } +} + +static void virtnet_rx_resume_all(struct virtnet_info *vi) +{ + bool running =3D netif_running(vi->dev); + int i; + + enable_delayed_refill(vi); + for (i =3D 0; i < vi->max_queue_pairs; i++) { + if (i < vi->curr_queue_pairs) { + if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) + schedule_delayed_work(&vi->refill, 0); + } + + if (running) + virtnet_napi_enable(&vi->rq[i]); + } +} + static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue= *rq) { bool running =3D netif_running(vi->dev); =20 + /* + * Make sure refill_work does not run concurrently to + * avoid napi_disable race which leads to deadlock. + */ + disable_delayed_refill(vi); + cancel_delayed_work_sync(&vi->refill); if (running) { virtnet_napi_disable(rq); virtnet_cancel_dim(vi, &rq->dim); @@ -3356,6 +3399,7 @@ static void virtnet_rx_resume(struct virtnet_info *vi= , struct receive_queue *rq) { bool running =3D netif_running(vi->dev); =20 + enable_delayed_refill(vi); if (!try_fill_recv(vi, rq, GFP_KERNEL)) schedule_delayed_work(&vi->refill, 0); =20 @@ -5959,12 +6003,12 @@ static int virtnet_xdp_set(struct net_device *dev, = struct bpf_prog *prog, if (prog) bpf_prog_add(prog, vi->max_queue_pairs - 1); =20 + virtnet_rx_pause_all(vi); + /* Make sure NAPI is not using any XDP TX queues for RX. */ if (netif_running(dev)) { - for (i =3D 0; i < vi->max_queue_pairs; i++) { - virtnet_napi_disable(&vi->rq[i]); + for (i =3D 0; i < vi->max_queue_pairs; i++) virtnet_napi_tx_disable(&vi->sq[i]); - } } =20 if (!prog) { @@ -5996,13 +6040,12 @@ static int virtnet_xdp_set(struct net_device *dev, = struct bpf_prog *prog, vi->xdp_enabled =3D false; } =20 + virtnet_rx_resume_all(vi); for (i =3D 0; i < vi->max_queue_pairs; i++) { if (old_prog) bpf_prog_put(old_prog); - if (netif_running(dev)) { - virtnet_napi_enable(&vi->rq[i]); + if (netif_running(dev)) virtnet_napi_tx_enable(&vi->sq[i]); - } } =20 return 0; @@ -6014,11 +6057,10 @@ static int virtnet_xdp_set(struct net_device *dev, = struct bpf_prog *prog, rcu_assign_pointer(vi->rq[i].xdp_prog, old_prog); } =20 + virtnet_rx_resume_all(vi); if (netif_running(dev)) { - for (i =3D 0; i < vi->max_queue_pairs; i++) { - virtnet_napi_enable(&vi->rq[i]); + for (i =3D 0; i < vi->max_queue_pairs; i++) virtnet_napi_tx_enable(&vi->sq[i]); - } } if (prog) bpf_prog_sub(prog, vi->max_queue_pairs - 1); --=20 2.43.0