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Wed, 24 Dec 2025 02:19:33 -0800 (PST) X-Google-Smtp-Source: AGHT+IFWh4eB5LClE32541NyP3GYu8yrLTSzO9/oko2wZ9FswtoXx/XEGhT13Drk8XxIX4u7HLPOVA== X-Received: by 2002:a05:600c:4711:b0:475:dd7f:f6cd with SMTP id 5b1f17b1804b1-47d19596ed2mr188269395e9.35.1766571572577; Wed, 24 Dec 2025 02:19:32 -0800 (PST) Received: from redhat.com ([31.187.78.137]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4324eab33f5sm33496423f8f.41.2025.12.24.02.19.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Dec 2025 02:19:32 -0800 (PST) Date: Wed, 24 Dec 2025 05:19:29 -0500 From: "Michael S. Tsirkin" To: Bui Quang Minh Cc: netdev@vger.kernel.org, Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , 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 Subject: Re: [PATCH net 1/3] virtio-net: make refill work a per receive queue work Message-ID: <20251224051747-mutt-send-email-mst@kernel.org> References: <20251223152533.24364-1-minhquangbui99@gmail.com> <20251223152533.24364-2-minhquangbui99@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251223152533.24364-2-minhquangbui99@gmail.com> On Tue, Dec 23, 2025 at 10:25:31PM +0700, Bui Quang Minh wrote: > Currently, the refill work is a global delayed work for all the receive > queues. This commit makes the refill work a per receive queue so that we > can manage them separately and avoid further mistakes. It also helps the > successfully refilled queue avoid the napi_disable in the global delayed > refill work like before. > this commit log is unreadable. before what? what is the problem with "refilled queue napi_disable" this refers to. > Signed-off-by: Bui Quang Minh > --- > drivers/net/virtio_net.c | 155 ++++++++++++++++++--------------------- > 1 file changed, 72 insertions(+), 83 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 1bb3aeca66c6..63126e490bda 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -379,6 +379,15 @@ struct receive_queue { > struct xdp_rxq_info xsk_rxq_info; > > struct xdp_buff **xsk_buffs; > + > + /* Is delayed refill enabled? */ > + bool refill_enabled; > + > + /* The lock to synchronize the access to refill_enabled */ > + spinlock_t refill_lock; > + > + /* Work struct for delayed refilling if we run low on memory. */ > + struct delayed_work refill; > }; > > #define VIRTIO_NET_RSS_MAX_KEY_SIZE 40 > @@ -441,9 +450,6 @@ struct virtnet_info { > /* Packet virtio header size */ > u8 hdr_len; > > - /* Work struct for delayed refilling if we run low on memory. */ > - struct delayed_work refill; > - > /* UDP tunnel support */ > bool tx_tnl; > > @@ -451,12 +457,6 @@ struct virtnet_info { > > bool rx_tnl_csum; > > - /* Is delayed refill enabled? */ > - bool refill_enabled; > - > - /* The lock to synchronize the access to refill_enabled */ > - spinlock_t refill_lock; > - > /* Work struct for config space updates */ > struct work_struct config_work; > > @@ -720,18 +720,18 @@ static void virtnet_rq_free_buf(struct virtnet_info *vi, > put_page(virt_to_head_page(buf)); > } > > -static void enable_delayed_refill(struct virtnet_info *vi) > +static void enable_delayed_refill(struct receive_queue *rq) > { > - spin_lock_bh(&vi->refill_lock); > - vi->refill_enabled = true; > - spin_unlock_bh(&vi->refill_lock); > + spin_lock_bh(&rq->refill_lock); > + rq->refill_enabled = true; > + spin_unlock_bh(&rq->refill_lock); > } > > -static void disable_delayed_refill(struct virtnet_info *vi) > +static void disable_delayed_refill(struct receive_queue *rq) > { > - spin_lock_bh(&vi->refill_lock); > - vi->refill_enabled = false; > - spin_unlock_bh(&vi->refill_lock); > + spin_lock_bh(&rq->refill_lock); > + rq->refill_enabled = false; > + spin_unlock_bh(&rq->refill_lock); > } > > static void enable_rx_mode_work(struct virtnet_info *vi) > @@ -2950,38 +2950,19 @@ static void virtnet_napi_disable(struct receive_queue *rq) > > static void refill_work(struct work_struct *work) > { > - struct virtnet_info *vi = > - container_of(work, struct virtnet_info, refill.work); > + struct receive_queue *rq = > + container_of(work, struct receive_queue, refill.work); > bool still_empty; > - int i; > - > - for (i = 0; i < vi->curr_queue_pairs; i++) { > - struct receive_queue *rq = &vi->rq[i]; > > - /* > - * When queue API support is added in the future and the call > - * below becomes napi_disable_locked, this driver will need to > - * be refactored. > - * > - * One possible solution would be to: > - * - cancel refill_work with cancel_delayed_work (note: > - * non-sync) > - * - cancel refill_work with cancel_delayed_work_sync in > - * virtnet_remove after the netdev is unregistered > - * - wrap all of the work in a lock (perhaps the netdev > - * instance lock) > - * - check netif_running() and return early to avoid a race > - */ > - napi_disable(&rq->napi); > - still_empty = !try_fill_recv(vi, rq, GFP_KERNEL); > - virtnet_napi_do_enable(rq->vq, &rq->napi); > + napi_disable(&rq->napi); > + still_empty = !try_fill_recv(rq->vq->vdev->priv, rq, GFP_KERNEL); > + virtnet_napi_do_enable(rq->vq, &rq->napi); > > - /* In theory, this can happen: if we don't get any buffers in > - * we will *never* try to fill again. > - */ > - if (still_empty) > - schedule_delayed_work(&vi->refill, HZ/2); > - } > + /* In theory, this can happen: if we don't get any buffers in > + * we will *never* try to fill again. > + */ > + if (still_empty) > + schedule_delayed_work(&rq->refill, HZ / 2); > } > > static int virtnet_receive_xsk_bufs(struct virtnet_info *vi, > @@ -3048,10 +3029,10 @@ static int virtnet_receive(struct receive_queue *rq, int budget, > > if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) { > if (!try_fill_recv(vi, rq, GFP_ATOMIC)) { > - spin_lock(&vi->refill_lock); > - if (vi->refill_enabled) > - schedule_delayed_work(&vi->refill, 0); > - spin_unlock(&vi->refill_lock); > + spin_lock(&rq->refill_lock); > + if (rq->refill_enabled) > + schedule_delayed_work(&rq->refill, 0); > + spin_unlock(&rq->refill_lock); > } > } > > @@ -3226,13 +3207,13 @@ 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) > + if (i < vi->curr_queue_pairs) { > + enable_delayed_refill(&vi->rq[i]); > /* 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); > + schedule_delayed_work(&vi->rq[i].refill, 0); > + } > > err = virtnet_enable_queue_pair(vi, i); > if (err < 0) > @@ -3251,10 +3232,9 @@ static int virtnet_open(struct net_device *dev) > return 0; > > err_enable_qp: > - disable_delayed_refill(vi); > - cancel_delayed_work_sync(&vi->refill); > - > for (i--; i >= 0; i--) { > + disable_delayed_refill(&vi->rq[i]); > + cancel_delayed_work_sync(&vi->rq[i].refill); > virtnet_disable_queue_pair(vi, i); > virtnet_cancel_dim(vi, &vi->rq[i].dim); > } > @@ -3447,14 +3427,15 @@ static void virtnet_rx_pause_all(struct virtnet_info *vi) > { > int i; > > - /* > - * 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); > - for (i = 0; i < vi->max_queue_pairs; i++) > + for (i = 0; i < vi->max_queue_pairs; i++) { > + /* > + * Make sure refill_work does not run concurrently to > + * avoid napi_disable race which leads to deadlock. > + */ > + disable_delayed_refill(&vi->rq[i]); > + cancel_delayed_work_sync(&vi->rq[i].refill); > __virtnet_rx_pause(vi, &vi->rq[i]); > + } > } > > static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue *rq) > @@ -3463,8 +3444,8 @@ static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue *rq) > * 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); > + disable_delayed_refill(rq); > + cancel_delayed_work_sync(&rq->refill); > __virtnet_rx_pause(vi, rq); > } > > @@ -3481,25 +3462,26 @@ static void __virtnet_rx_resume(struct virtnet_info *vi, > virtnet_napi_enable(rq); > > if (schedule_refill) > - schedule_delayed_work(&vi->refill, 0); > + schedule_delayed_work(&rq->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) > + if (i < vi->curr_queue_pairs) { > + enable_delayed_refill(&vi->rq[i]); > __virtnet_rx_resume(vi, &vi->rq[i], true); > - else > + } else { > __virtnet_rx_resume(vi, &vi->rq[i], false); > + } > } > } > > static void virtnet_rx_resume(struct virtnet_info *vi, struct receive_queue *rq) > { > - enable_delayed_refill(vi); > + enable_delayed_refill(rq); > __virtnet_rx_resume(vi, rq, true); > } > > @@ -3830,10 +3812,16 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) > succ: > vi->curr_queue_pairs = queue_pairs; > /* virtnet_open() will refill when device is going to up. */ > - spin_lock_bh(&vi->refill_lock); > - if (dev->flags & IFF_UP && vi->refill_enabled) > - schedule_delayed_work(&vi->refill, 0); > - spin_unlock_bh(&vi->refill_lock); > + if (dev->flags & IFF_UP) { > + int i; > + > + for (i = 0; i < vi->curr_queue_pairs; i++) { > + spin_lock_bh(&vi->rq[i].refill_lock); > + if (vi->rq[i].refill_enabled) > + schedule_delayed_work(&vi->rq[i].refill, 0); > + spin_unlock_bh(&vi->rq[i].refill_lock); > + } > + } > > return 0; > } > @@ -3843,10 +3831,6 @@ static int virtnet_close(struct net_device *dev) > struct virtnet_info *vi = netdev_priv(dev); > int i; > > - /* Make sure NAPI doesn't schedule refill work */ > - disable_delayed_refill(vi); > - /* Make sure refill_work doesn't re-enable napi! */ > - cancel_delayed_work_sync(&vi->refill); > /* Prevent the config change callback from changing carrier > * after close > */ > @@ -3857,6 +3841,10 @@ static int virtnet_close(struct net_device *dev) > cancel_work_sync(&vi->config_work); > > for (i = 0; i < vi->max_queue_pairs; i++) { > + /* Make sure NAPI doesn't schedule refill work */ > + disable_delayed_refill(&vi->rq[i]); > + /* Make sure refill_work doesn't re-enable napi! */ > + cancel_delayed_work_sync(&vi->rq[i].refill); > virtnet_disable_queue_pair(vi, i); > virtnet_cancel_dim(vi, &vi->rq[i].dim); > } > @@ -5802,7 +5790,6 @@ static int virtnet_restore_up(struct virtio_device *vdev) > > virtio_device_ready(vdev); > > - enable_delayed_refill(vi); > enable_rx_mode_work(vi); > > if (netif_running(vi->dev)) { > @@ -6559,8 +6546,9 @@ static int virtnet_alloc_queues(struct virtnet_info *vi) > if (!vi->rq) > goto err_rq; > > - INIT_DELAYED_WORK(&vi->refill, refill_work); > for (i = 0; i < vi->max_queue_pairs; i++) { > + INIT_DELAYED_WORK(&vi->rq[i].refill, refill_work); > + spin_lock_init(&vi->rq[i].refill_lock); > vi->rq[i].pages = NULL; > netif_napi_add_config(vi->dev, &vi->rq[i].napi, virtnet_poll, > i); > @@ -6901,7 +6889,6 @@ static int virtnet_probe(struct virtio_device *vdev) > > INIT_WORK(&vi->config_work, virtnet_config_changed_work); > INIT_WORK(&vi->rx_mode_work, virtnet_rx_mode_work); > - spin_lock_init(&vi->refill_lock); > > if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) { > vi->mergeable_rx_bufs = true; > @@ -7165,7 +7152,9 @@ static int virtnet_probe(struct virtio_device *vdev) > net_failover_destroy(vi->failover); > free_vqs: > virtio_reset_device(vdev); > - cancel_delayed_work_sync(&vi->refill); > + for (i = 0; i < vi->max_queue_pairs; i++) > + cancel_delayed_work_sync(&vi->rq[i].refill); > + > free_receive_page_frags(vi); > virtnet_del_vqs(vi); > free: > -- > 2.43.0