Commit 48c57a49 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'virtio-net-link-queues-to-napis' 

Joe Damato says:

====================
virtio-net: Link queues to NAPIs

Jakub recently commented [1] that I should not hold this series on
virtio-net linking queues to NAPIs behind other important work that is
on-going and suggested I re-spin, so here we are :)

As per the discussion on the v3 [2], now both RX and TX NAPIs use the
API to link queues to NAPIs. Since TX-only NAPIs don't have a NAPI ID,
commit 6597e8d3 ("netdev-genl: Elide napi_id when not present") now
correctly elides the TX-only NAPIs (instead of printing zero) when the
queues and NAPIs are linked.

As per the discussion on the v4 [3], patch 3 has been refactored to hold
RTNL only in the specific locations which need it as Jason requested.

As per the discussion on the v5 [4], patch 3 now leaves refill_work
as-is and does not use the API to unlink and relink queues and NAPIs. A
comment has been left as suggested by Jakub [5] for future work.

See the commit message of patch 3 for an example of how to get the NAPI
to queue mapping information.

See the commit message of patch 4 for an example of how NAPI IDs are
persistent despite queue count changes.

[1]: https://lore.kernel.org/20250221142650.3c74dcac@kernel.org
[2]: https://lore.kernel.org/20250127142400.24eca319@kernel.org
[3]: https://lore.kernel.org/CACGkMEv=ejJnOWDnAu7eULLvrqXjkMkTL4cbi-uCTUhCpKN_GA@mail.gmail.com
[4]: https://lore.kernel.org/Z8X15hxz8t-vXpPU@LQ3V64L9R2
[5]: https://lore.kernel.org/20250303160355.5f8d82d8@kernel.org

v5: https://lore.kernel.org/20250227185017.206785-1-jdamato@fastly.com
v4: https://lore.kernel.org/20250225020455.212895-1-jdamato@fastly.com
rfcv3: https://lore.kernel.org/20250121191047.269844-1-jdamato@fastly.com
v2: https://lore.kernel.org/20250116055302.14308-1-jdamato@fastly.com
v1: https://lore.kernel.org/20250110202605.429475-1-jdamato@fastly.com
====================

Link: https://patch.msgid.link/20250307011215.266806-1-jdamato@fastly.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 8ef890df d5d71520

drivers/net/virtio_net.c

+74 −27
Original line number Diff line number Diff line
@@ -2807,7 +2807,8 @@ static void skb_recv_done(struct virtqueue *rvq) 
	virtqueue_napi_schedule(&rq->napi, rvq);

}



static void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi)

static void virtnet_napi_do_enable(struct virtqueue *vq,

				   struct napi_struct *napi)

{

	napi_enable(napi);
@@ -2820,10 +2821,21 @@ static void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi) 
	local_bh_enable();

}



static void virtnet_napi_tx_enable(struct virtnet_info *vi,

				   struct virtqueue *vq,

				   struct napi_struct *napi)

static void virtnet_napi_enable(struct receive_queue *rq)

{

	struct virtnet_info *vi = rq->vq->vdev->priv;

	int qidx = vq2rxq(rq->vq);



	virtnet_napi_do_enable(rq->vq, &rq->napi);

	netif_queue_set_napi(vi->dev, qidx, NETDEV_QUEUE_TYPE_RX, &rq->napi);

}



static void virtnet_napi_tx_enable(struct send_queue *sq)

{

	struct virtnet_info *vi = sq->vq->vdev->priv;

	struct napi_struct *napi = &sq->napi;

	int qidx = vq2txq(sq->vq);



	if (!napi->weight)

		return;
@@ -2835,12 +2847,29 @@ static void virtnet_napi_tx_enable(struct virtnet_info *vi, 
		return;

	}



	return virtnet_napi_enable(vq, napi);

	virtnet_napi_do_enable(sq->vq, napi);

	netif_queue_set_napi(vi->dev, qidx, NETDEV_QUEUE_TYPE_TX, napi);

}



static void virtnet_napi_tx_disable(struct napi_struct *napi)

static void virtnet_napi_tx_disable(struct send_queue *sq)

{

	if (napi->weight)

	struct virtnet_info *vi = sq->vq->vdev->priv;

	struct napi_struct *napi = &sq->napi;

	int qidx = vq2txq(sq->vq);



	if (napi->weight) {

		netif_queue_set_napi(vi->dev, qidx, NETDEV_QUEUE_TYPE_TX, NULL);

		napi_disable(napi);

	}

}



static void virtnet_napi_disable(struct receive_queue *rq)

{

	struct virtnet_info *vi = rq->vq->vdev->priv;

	struct napi_struct *napi = &rq->napi;

	int qidx = vq2rxq(rq->vq);



	netif_queue_set_napi(vi->dev, qidx, NETDEV_QUEUE_TYPE_RX, NULL);

	napi_disable(napi);

}
@@ -2854,9 +2883,23 @@ static void refill_work(struct work_struct *work) 
	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_enable(rq->vq, &rq->napi);

		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.
@@ -3053,8 +3096,8 @@ static int virtnet_poll(struct napi_struct *napi, int budget) 


static void virtnet_disable_queue_pair(struct virtnet_info *vi, int qp_index)

{

	virtnet_napi_tx_disable(&vi->sq[qp_index].napi);

	napi_disable(&vi->rq[qp_index].napi);

	virtnet_napi_tx_disable(&vi->sq[qp_index]);

	virtnet_napi_disable(&vi->rq[qp_index]);

	xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);

}
@@ -3073,8 +3116,8 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index) 
	if (err < 0)

		goto err_xdp_reg_mem_model;



	virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);

	virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);

	virtnet_napi_enable(&vi->rq[qp_index]);

	virtnet_napi_tx_enable(&vi->sq[qp_index]);



	return 0;
@@ -3326,7 +3369,7 @@ static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue *rq) 
	bool running = netif_running(vi->dev);



	if (running) {

		napi_disable(&rq->napi);

		virtnet_napi_disable(rq);

		virtnet_cancel_dim(vi, &rq->dim);

	}

}
@@ -3339,7 +3382,7 @@ static void virtnet_rx_resume(struct virtnet_info *vi, struct receive_queue *rq) 
		schedule_delayed_work(&vi->refill, 0);



	if (running)

		virtnet_napi_enable(rq->vq, &rq->napi);

		virtnet_napi_enable(rq);

}



static int virtnet_rx_resize(struct virtnet_info *vi,
@@ -3368,7 +3411,7 @@ static void virtnet_tx_pause(struct virtnet_info *vi, struct send_queue *sq) 
	qindex = sq - vi->sq;



	if (running)

		virtnet_napi_tx_disable(&sq->napi);

		virtnet_napi_tx_disable(sq);



	txq = netdev_get_tx_queue(vi->dev, qindex);
@@ -3402,7 +3445,7 @@ static void virtnet_tx_resume(struct virtnet_info *vi, struct send_queue *sq) 
	__netif_tx_unlock_bh(txq);



	if (running)

		virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);

		virtnet_napi_tx_enable(sq);

}



static int virtnet_tx_resize(struct virtnet_info *vi, struct send_queue *sq,
@@ -5634,8 +5677,11 @@ static void virtnet_freeze_down(struct virtio_device *vdev) 
	netif_tx_lock_bh(vi->dev);

	netif_device_detach(vi->dev);

	netif_tx_unlock_bh(vi->dev);

	if (netif_running(vi->dev))

	if (netif_running(vi->dev)) {

		rtnl_lock();

		virtnet_close(vi->dev);

		rtnl_unlock();

	}

}



static int init_vqs(struct virtnet_info *vi);
@@ -5655,7 +5701,9 @@ static int virtnet_restore_up(struct virtio_device *vdev) 
	enable_rx_mode_work(vi);



	if (netif_running(vi->dev)) {

		rtnl_lock();

		err = virtnet_open(vi->dev);

		rtnl_unlock();

		if (err)

			return err;

	}
@@ -5945,8 +5993,8 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, 
	/* Make sure NAPI is not using any XDP TX queues for RX. */

	if (netif_running(dev)) {

		for (i = 0; i < vi->max_queue_pairs; i++) {

			napi_disable(&vi->rq[i].napi);

			virtnet_napi_tx_disable(&vi->sq[i].napi);

			virtnet_napi_disable(&vi->rq[i]);

			virtnet_napi_tx_disable(&vi->sq[i]);

		}

	}
@@ -5983,9 +6031,8 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, 
		if (old_prog)

			bpf_prog_put(old_prog);

		if (netif_running(dev)) {

			virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);

			virtnet_napi_tx_enable(vi, vi->sq[i].vq,

					       &vi->sq[i].napi);

			virtnet_napi_enable(&vi->rq[i]);

			virtnet_napi_tx_enable(&vi->sq[i]);

		}

	}
@@ -6000,9 +6047,8 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, 


	if (netif_running(dev)) {

		for (i = 0; i < vi->max_queue_pairs; i++) {

			virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);

			virtnet_napi_tx_enable(vi, vi->sq[i].vq,

					       &vi->sq[i].napi);

			virtnet_napi_enable(&vi->rq[i]);

			virtnet_napi_tx_enable(&vi->sq[i]);

		}

	}

	if (prog)
@@ -6409,8 +6455,9 @@ static int virtnet_alloc_queues(struct virtnet_info *vi) 
	INIT_DELAYED_WORK(&vi->refill, refill_work);

	for (i = 0; i < vi->max_queue_pairs; i++) {

		vi->rq[i].pages = NULL;

		netif_napi_add_weight(vi->dev, &vi->rq[i].napi, virtnet_poll,

				      napi_weight);

		netif_napi_add_config(vi->dev, &vi->rq[i].napi, virtnet_poll,

				      i);

		vi->rq[i].napi.weight = napi_weight;

		netif_napi_add_tx_weight(vi->dev, &vi->sq[i].napi,

					 virtnet_poll_tx,

					 napi_tx ? napi_weight : 0);