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([2001:ee0:4f4e:bd30:2142:e08e:e207:d31c]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-739d9805a00sm1144603b3a.81.2025.04.03.03.43.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Apr 2025 03:43:33 -0700 (PDT) Message-ID: <8aad5ff9-6eab-411d-9569-9a2303561ac0@gmail.com> Date: Thu, 3 Apr 2025 17:43:26 +0700 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] virtio-net: disable delayed refill when setting up xdp To: virtualization@lists.linux.dev Cc: "Michael S . 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_P=C3=A9rez?= , "David S . Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org References: <20250402054210.67623-1-minhquangbui99@gmail.com> Content-Language: en-US From: Bui Quang Minh In-Reply-To: <20250402054210.67623-1-minhquangbui99@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/2/25 12:42, 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 > --- > 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); > + } > + > if (prog) > bpf_prog_add(prog, vi->max_queue_pairs - 1); > > @@ -6004,6 +6013,8 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, > virtnet_napi_tx_enable(&vi->sq[i]); > } > } > + if (netif_running(dev)) > + enable_delayed_refill(vi); While doing some testing, it look likes that we must call try_fill_recv to resume the rx path. I'll do more testing and send a new v2 patch. > > return 0; > > @@ -6019,6 +6030,7 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, > virtnet_napi_enable(&vi->rq[i]); > virtnet_napi_tx_enable(&vi->sq[i]); > } > + enable_delayed_refill(vi); > } > if (prog) > bpf_prog_sub(prog, vi->max_queue_pairs - 1);