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([2001:ee0:4f4c:210:c711:242:cd10:6c98]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c1e7961b4d0sm14833334a12.5.2025.12.24.09.03.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Dec 2025 09:03:11 -0800 (PST) Message-ID: <0d5469f9-9918-4707-a390-533f53eadbe4@gmail.com> Date: Thu, 25 Dec 2025 00:03:05 +0700 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net 1/3] virtio-net: make refill work a per receive queue work To: "Michael S. Tsirkin" Cc: netdev@vger.kernel.org, Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=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 References: <20251223152533.24364-1-minhquangbui99@gmail.com> <20251223152533.24364-2-minhquangbui99@gmail.com> <20251224051747-mutt-send-email-mst@kernel.org> Content-Language: en-US From: Bui Quang Minh In-Reply-To: <20251224051747-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/24/25 17:19, Michael S. Tsirkin wrote: > 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. I mean that currently even if one RX queue is refilled successfully but another is not, then the successful one still gets napi_disable() in the global refill work. It will unnecessarily disrupt that queue I think. > >> 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