Subject: Re: [PATCH net-next 2/3] virtio_net: multiqueue support

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 4 Dec 2012 17:11:08 +0200

On Tue, Dec 04, 2012 at 10:45:33PM +0800, Jason Wang wrote:
> On Tuesday, December 04, 2012 03:24:22 PM Michael S. Tsirkin wrote:
> > I found some bugs, see below.
> > Also some style nitpicking, this is not mandatory to address.
> 
> Thanks for the reviewing.
> > 
> > On Tue, Dec 04, 2012 at 07:07:57PM +0800, Jason Wang wrote:
> > > This addes multiqueue support to virtio_net driver. In multiple queue
> > > modes, the driver expects the number of queue paris is equal to the
> > > number of vcpus. To eliminate the contention bettwen vcpus and
> > > virtqueues, per-cpu virtqueue pairs
> > > were implemented through:
> > Lots of typos above - try running ispell on it :)
> > 
> 
> Sure.
> > > - select the txq based on the smp processor id.
> > > - smp affinity hint were set to the vcpu that owns the queue pairs.
> > > 
> > > Signed-off-by: Krishna Kumar <[email-masked]>
> > > Signed-off-by: Jason Wang <[email-masked]>
> > > ---
> > > 
> > >  drivers/net/virtio_net.c        |  472
> > >  ++++++++++++++++++++++++++++++--------- include/uapi/linux/virtio_net.h
> > >  |   16 ++
> > >  2 files changed, 385 insertions(+), 103 deletions(-)
> > > 
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index 266f712..912f5b2 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -81,16 +81,25 @@ struct virtnet_info {
> > > 
> > >  	struct virtio_device *vdev;
> > >  	struct virtqueue *cvq;
> > >  	struct net_device *dev;
> > > 
> > > -	struct send_queue sq;
> > > -	struct receive_queue rq;
> > > +	struct send_queue *sq;
> > > +	struct receive_queue *rq;
> > > 
> > >  	unsigned int status;
> > > 
> > > +	/* Max # of queue pairs supported by the device */
> > > +	u16 max_queue_pairs;
> > > +
> > > +	/* # of queue pairs currently used by the driver */
> > > +	u16 curr_queue_pairs;
> > > +
> > > 
> > >  	/* I like... big packets and I cannot lie! */
> > >  	bool big_packets;
> > >  	
> > >  	/* Host will merge rx buffers for big packets (shake it! shake it!) */
> > >  	bool mergeable_rx_bufs;
> > > 
> > > +	/* Has control virtqueue */
> > > +	bool has_cvq;
> > > +
> > > 
> > >  	/* enable config space updates */
> > >  	bool config_enable;
> > > 
> > > @@ -125,6 +134,32 @@ struct padded_vnet_hdr {
> > > 
> > >  	char padding[6];
> > >  
> > >  };
> > > 
> > > +static const struct ethtool_ops virtnet_ethtool_ops;
> > > +
> > > +
> > > +/* Converting between virtqueue no. and kernel tx/rx queue no.
> > > + * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq
> > > + */
> > > +static int vq2txq(struct virtqueue *vq)
> > > +{
> > > +	return (virtqueue_get_queue_index(vq) - 1) / 2;
> > > +}
> > > +
> > > +static int txq2vq(int txq)
> > > +{
> > > +	return txq * 2 + 1;
> > > +}
> > > +
> > > +static int vq2rxq(struct virtqueue *vq)
> > > +{
> > > +	return virtqueue_get_queue_index(vq) / 2;
> > > +}
> > > +
> > > +static int rxq2vq(int rxq)
> > > +{
> > > +	return rxq * 2;
> > > +}
> > > +
> > > 
> > >  static inline struct skb_vnet_hdr *skb_vnet_hdr(struct sk_buff *skb)
> > >  {
> > >  
> > >  	return (struct skb_vnet_hdr *)skb->cb;
> > > 
> > > @@ -165,7 +200,7 @@ static void skb_xmit_done(struct virtqueue *vq)
> > > 
> > >  	virtqueue_disable_cb(vq);
> > >  	
> > >  	/* We were probably waiting for more output buffers. */
> > > 
> > > -	netif_wake_queue(vi->dev);
> > > +	netif_wake_subqueue(vi->dev, vq2txq(vq));
> > > 
> > >  }
> > >  
> > >  static void set_skb_frag(struct sk_buff *skb, struct page *page,
> > > 
> > > @@ -502,7 +537,7 @@ static bool try_fill_recv(struct receive_queue *rq,
> > > gfp_t gfp)> 
> > >  static void skb_recv_done(struct virtqueue *rvq)
> > >  {
> > >  
> > >  	struct virtnet_info *vi = rvq->vdev->priv;
> > > 
> > > -	struct receive_queue *rq = &vi->rq;
> > > +	struct receive_queue *rq = &vi->rq[vq2rxq(rvq)];
> > > 
> > >  	/* Schedule NAPI, Suppress further interrupts if successful. */
> > >  	if (napi_schedule_prep(&rq->napi)) {
> > > 
> > > @@ -532,15 +567,21 @@ static void refill_work(struct work_struct *work)
> > > 
> > >  	struct virtnet_info *vi =
> > >  	
> > >  		container_of(work, struct virtnet_info, refill.work);
> > >  	
> > >  	bool still_empty;
> > > 
> > > +	int i;
> > > +
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		struct receive_queue *rq = &vi->rq[i];
> > > 
> > > -	napi_disable(&vi->rq.napi);
> > > -	still_empty = !try_fill_recv(&vi->rq, GFP_KERNEL);
> > > -	virtnet_napi_enable(&vi->rq);
> > > +		napi_disable(&rq->napi);
> > > +		still_empty = !try_fill_recv(rq, GFP_KERNEL);
> > > +		virtnet_napi_enable(rq);
> > > 
> > > -	/* 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(&vi->refill, HZ/2);
> > > +	}
> > > 
> > >  }
> > >  
> > >  static int virtnet_poll(struct napi_struct *napi, int budget)
> > > 
> > > @@ -650,7 +691,8 @@ static int xmit_skb(struct send_queue *sq, struct
> > > sk_buff *skb)> 
> > >  static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device
> > >  *dev)
> > >  {
> > >  
> > >  	struct virtnet_info *vi = netdev_priv(dev);
> > > 
> > > -	struct send_queue *sq = &vi->sq;
> > > +	int qnum = skb_get_queue_mapping(skb);
> > > +	struct send_queue *sq = &vi->sq[qnum];
> > > 
> > >  	int capacity;
> > >  	
> > >  	/* Free up any pending old buffers before queueing new ones. */
> > > 
> > > @@ -664,13 +706,14 @@ static netdev_tx_t start_xmit(struct sk_buff *skb,
> > > struct net_device *dev)> 
> > >  		if (likely(capacity == -ENOMEM)) {
> > >  		
> > >  			if (net_ratelimit())
> > >  			
> > >  				dev_warn(&dev->dev,
> > > 
> > > -					 "TX queue failure: out of memory\n");
> > > +					 "TXQ (%d) failure: out of memory\n",
> > > +					 qnum);
> > > 
> > >  		} else {
> > >  		
> > >  			dev->stats.tx_fifo_errors++;
> > >  			if (net_ratelimit())
> > >  			
> > >  				dev_warn(&dev->dev,
> > > 
> > > -					 "Unexpected TX queue failure: %d\n",
> > > -					 capacity);
> > > +					 "Unexpected TXQ (%d) failure: %d\n",
> > > +					 qnum, capacity);
> > > 
> > >  		}
> > >  		dev->stats.tx_dropped++;
> > >  		kfree_skb(skb);
> > > 
> > > @@ -685,12 +728,12 @@ static netdev_tx_t start_xmit(struct sk_buff *skb,
> > > struct net_device *dev)> 
> > >  	/* Apparently nice girls don't return TX_BUSY; stop the queue
> > >  	
> > >  	 * before it gets out of hand.  Naturally, this wastes entries. */
> > >  	
> > >  	if (capacity < 2+MAX_SKB_FRAGS) {
> > > 
> > > -		netif_stop_queue(dev);
> > > +		netif_stop_subqueue(dev, qnum);
> > > 
> > >  		if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
> > >  		
> > >  			/* More just got used, free them then recheck. */
> > >  			capacity += free_old_xmit_skbs(sq);
> > >  			if (capacity >= 2+MAX_SKB_FRAGS) {
> > > 
> > > -				netif_start_queue(dev);
> > > +				netif_start_subqueue(dev, qnum);
> > > 
> > >  				virtqueue_disable_cb(sq->vq);
> > >  			
> > >  			}
> > >  		
> > >  		}
> > > 
> > > @@ -758,23 +801,13 @@ static struct rtnl_link_stats64
> > > *virtnet_stats(struct net_device *dev,> 
> > >  static void virtnet_netpoll(struct net_device *dev)
> > >  {
> > >  
> > >  	struct virtnet_info *vi = netdev_priv(dev);
> > > 
> > > +	int i;
> > > 
> > > -	napi_schedule(&vi->rq.napi);
> > > +	for (i = 0; i < vi->curr_queue_pairs; i++)
> > > +		napi_schedule(&vi->rq[i].napi);
> > > 
> > >  }
> > >  #endif
> > > 
> > > -static int virtnet_open(struct net_device *dev)
> > > -{
> > > -	struct virtnet_info *vi = netdev_priv(dev);
> > > -
> > > -	/* Make sure we have some buffers: if oom use wq. */
> > > -	if (!try_fill_recv(&vi->rq, GFP_KERNEL))
> > > -		schedule_delayed_work(&vi->refill, 0);
> > > -
> > > -	virtnet_napi_enable(&vi->rq);
> > > -	return 0;
> > > -}
> > > -
> > > 
> > >  /*
> > >  
> > >   * Send command via the control virtqueue and check status.  Commands
> > >   * supported by the hypervisor, as indicated by feature bits, should
> > > 
> > > @@ -830,13 +863,51 @@ static void virtnet_ack_link_announce(struct
> > > virtnet_info *vi)> 
> > >  	rtnl_unlock();
> > >  
> > >  }
> > > 
> > > +/* Caller check the support of cvq and multiqueue. */
> > > +static int virtnet_set_queues(struct virtnet_info *vi)
> > > +{
> > > +	struct scatterlist sg;
> > > +	struct virtio_net_ctrl_rfs s;
> > > +	struct net_device *dev = vi->dev;
> > > +
> > > +	s.virtqueue_pairs = vi->curr_queue_pairs;
> > > +	sg_init_one(&sg, &s, sizeof(s));
> > > +
> > > +	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_RFS,
> > > +				  VIRTIO_NET_CTRL_RFS_VQ_PAIRS_SET, &sg, 1, 0)){
> > > +		dev_warn(&dev->dev, "Fail to set num of queue pairs to %d\n",
> > > +			 vi->curr_queue_pairs);
> > > +		return -EINVAL;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int virtnet_open(struct net_device *dev)
> > 
> > Why move this here? diff will be smaller if you don't.
> 
> Ok, will move it back.
> > 
> > > +{
> > > +	struct virtnet_info *vi = netdev_priv(dev);
> > > +	int i;
> > > +
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		/* Make sure we have some buffers: if oom use wq. */
> > > +		if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
> > > +			schedule_delayed_work(&vi->refill, 0);
> > > +		virtnet_napi_enable(&vi->rq[i]);
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > 
> > >  static int virtnet_close(struct net_device *dev)
> > >  {
> > >  
> > >  	struct virtnet_info *vi = netdev_priv(dev);
> > > 
> > > +	int i;
> > > 
> > >  	/* Make sure refill_work doesn't re-enable napi! */
> > >  	cancel_delayed_work_sync(&vi->refill);
> > > 
> > > -	napi_disable(&vi->rq.napi);
> > > +
> > > +	for (i = 0; i < vi->max_queue_pairs; i++)
> > > +		napi_disable(&vi->rq[i].napi);
> > > 
> > >  	return 0;
> > >  
> > >  }
> > > 
> > > @@ -948,8 +1019,8 @@ static void virtnet_get_ringparam(struct net_device
> > > *dev,> 
> > >  {
> > >  
> > >  	struct virtnet_info *vi = netdev_priv(dev);
> > > 
> > > -	ring->rx_max_pending = virtqueue_get_vring_size(vi->rq.vq);
> > > -	ring->tx_max_pending = virtqueue_get_vring_size(vi->sq.vq);
> > > +	ring->rx_max_pending = virtqueue_get_vring_size(vi->rq[0].vq);
> > > +	ring->tx_max_pending = virtqueue_get_vring_size(vi->sq[0].vq);
> > > 
> > >  	ring->rx_pending = ring->rx_max_pending;
> > >  	ring->tx_pending = ring->tx_max_pending;
> > >  
> > >  }
> > > 
> > > @@ -967,12 +1038,6 @@ static void virtnet_get_drvinfo(struct net_device
> > > *dev,> 
> > >  }
> > > 
> > > -static const struct ethtool_ops virtnet_ethtool_ops = {
> > > -	.get_drvinfo = virtnet_get_drvinfo,
> > > -	.get_link = ethtool_op_get_link,
> > > -	.get_ringparam = virtnet_get_ringparam,
> > > -};
> > > -
> > > 
> > >  #define MIN_MTU 68
> > >  #define MAX_MTU 65535
> > > 
> > > @@ -984,6 +1049,21 @@ static int virtnet_change_mtu(struct net_device
> > > *dev, int new_mtu)> 
> > >  	return 0;
> > >  
> > >  }
> > > 
> > > +/* To avoid contending a lock hold by a vcpu who would exit to host,
> > > select the + * txq based on the processor id.
> > > + * TODO: handle cpu hotplug.
> > > + */
> > > +static u16 virtnet_select_queue(struct net_device *dev, struct sk_buff
> > > *skb) +{
> > > +	int txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) :
> > > +		  smp_processor_id();
> > > +
> > > +	while (unlikely(txq >= dev->real_num_tx_queues))
> > > +		txq -= dev->real_num_tx_queues;
> > > +
> > > +	return txq;
> > > +}
> > > +
> > > 
> > >  static const struct net_device_ops virtnet_netdev = {
> > >  
> > >  	.ndo_open            = virtnet_open,
> > >  	.ndo_stop   	     = virtnet_close,
> > > 
> > > @@ -995,6 +1075,7 @@ static const struct net_device_ops virtnet_netdev = {
> > > 
> > >  	.ndo_get_stats64     = virtnet_stats,
> > >  	.ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid,
> > >  	.ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
> > > 
> > > +	.ndo_select_queue     = virtnet_select_queue,
> > > 
> > >  #ifdef CONFIG_NET_POLL_CONTROLLER
> > >  
> > >  	.ndo_poll_controller = virtnet_netpoll,
> > >  
> > >  #endif
> > > 
> > > @@ -1030,10 +1111,10 @@ static void virtnet_config_changed_work(struct
> > > work_struct *work)> 
> > >  	if (vi->status & VIRTIO_NET_S_LINK_UP) {
> > >  	
> > >  		netif_carrier_on(vi->dev);
> > > 
> > > -		netif_wake_queue(vi->dev);
> > > +		netif_tx_wake_all_queues(vi->dev);
> > > 
> > >  	} else {
> > >  	
> > >  		netif_carrier_off(vi->dev);
> > > 
> > > -		netif_stop_queue(vi->dev);
> > > +		netif_tx_stop_all_queues(vi->dev);
> > > 
> > >  	}
> > >  
> > >  done:
> > >  	mutex_unlock(&vi->config_lock);
> > > 
> > > @@ -1046,41 +1127,219 @@ static void virtnet_config_changed(struct
> > > virtio_device *vdev)> 
> > >  	schedule_work(&vi->config_work);
> > >  
> > >  }
> > > 
> > > -static int init_vqs(struct virtnet_info *vi)
> > > +static void free_receive_bufs(struct virtnet_info *vi)
> > > 
> > >  {
> > > 
> > > -	struct virtqueue *vqs[3];
> > > -	vq_callback_t *callbacks[] = { skb_recv_done, skb_xmit_done, NULL};
> > > -	const char *names[] = { "input", "output", "control" };
> > > -	int nvqs, err;
> > > +	int i;
> > > 
> > > -	/* We expect two virtqueues, receive then send,
> > > -	 * and optionally control. */
> > > -	nvqs = virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ) ? 3 : 2;
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		while (vi->rq[i].pages)
> > > +			__free_pages(get_a_page(&vi->rq[i], GFP_KERNEL), 0);
> > > +	}
> > > +}
> > > 
> > > -	err = vi->vdev->config->find_vqs(vi->vdev, nvqs, vqs, callbacks, names);
> > > -	if (err)
> > > -		return err;
> > > +/* Free memory allocated for send and receive queues */
> > > +static void virtnet_free_queues(struct virtnet_info *vi)
> > 
> > I think it's cleaner to open-code this, this way
> > during error handling you can have:
> > 
> > 	kfree(vi->rq);
> > err_rq:
> > 	kfree(vi->sq);
> > err_sq:
> > 
> > without tricks like malloc them both then goto end.
> 
> Ok.
> > 
> > > +{
> > > +	kfree(vi->rq);
> > > +	vi->rq = NULL;
> > > +	kfree(vi->sq);
> > > +	vi->sq = NULL;
> > 
> > I think = NULL is not needed - we never call this twice.
> 
> Sure, will remove it.
> > 
> > > +}
> > > +
> > > +static void free_unused_bufs(struct virtnet_info *vi)
> > > +{
> > > +	void *buf;
> > > +	int i;
> > > +
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		struct virtqueue *vq = vi->sq[i].vq;
> > > +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > > +			dev_kfree_skb(buf);
> > > +	}
> > > +
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		struct virtqueue *vq = vi->rq[i].vq;
> > > +
> > > +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) {
> > > +			if (vi->mergeable_rx_bufs || vi->big_packets)
> > > +				give_pages(&vi->rq[i], buf);
> > > +			else
> > > +				dev_kfree_skb(buf);
> > > +			--vi->rq[i].num;
> > > +		}
> > > +		BUG_ON(vi->rq[i].num != 0);
> > > +	}
> > > +}
> > > +
> > > +static void virtnet_set_affinity(struct virtnet_info *vi, bool set)
> > > +{
> > > +	int i;
> > > +
> > > +	/* Don't set the affinity hint when in single queue mode or we have too
> > > +	 * much online cpus.
> > > +	 */
> > 
> > Pls remove this comment, or replace with one explaining
> > the motivation for this logic.
> 
> Will replace with the motivation.
> > 
> > > +	if (vi->curr_queue_pairs == 1 ||
> > > +	    vi->max_queue_pairs > num_online_cpus())
> > 
> > If we have less it's not a good idea either, is it?
> > So check vi->max_queue_pairs != num_online_cpus().
> 
> Ok.
> > 
> > > +		set = false;
> > 
> > This will overwrite affinity if it was set by userspace.
> > Just
> > 	if (set)
> > 		return;
> > will not have this problem.
> 
> But we need handle the situtaiton when switch back to sq from mq mode. 
> Otherwise we may still get the affinity hint used in mq.
>  This kind of overwrite 
> is unavoidable or is there some method to detect whether userspac write 
> something new?

If we didn't set the affinity originally we should not overwrite it.
I think this means we need a flag that tells us that
virtio set the affinity.

> > 
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		int cpu = set ? i : -1;
> > > +		virtqueue_set_affinity(vi->rq[i].vq, cpu);
> > > +		virtqueue_set_affinity(vi->sq[i].vq, cpu);
> > > +	}
> > > +}
> > > +
> > > +static void virtnet_del_vqs(struct virtnet_info *vi)
> > 
> > It might be a good idea to add this function in previous
> > patch.
> 
> Yes, good suggetion.
> > 
> > > +{
> > > +	struct virtio_device *vdev = vi->vdev;
> > > +
> > > +	virtnet_set_affinity(vi, false);
> > > +
> > > +	vdev->config->del_vqs(vdev);
> > > 
> > > -	vi->rq.vq = vqs[0];
> > > -	vi->sq.vq = vqs[1];
> > > +	virtnet_free_queues(vi);
> > > +}
> > > 
> > > -	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)) {
> > > -		vi->cvq = vqs[2];
> > > +static int virtnet_find_vqs(struct virtnet_info *vi)
> > > +{
> > > +	vq_callback_t **callbacks;
> > > +	struct virtqueue **vqs;
> > > +	int ret = -ENOMEM;
> > > +	int i, total_vqs;
> > > +	char **names;
> > > +
> > > +	/* We expect 1 RX virtqueue followed by 1 TX virtqueue, followd by
> > 
> > followed
> > 
> 
> Ok, will correct it.
> > > +	 * possible N-1 RX/TX queue pairs used in multiqueue mode, followed by
> > > +	 * possible control vq.
> > > +	 */
> > > +	total_vqs = vi->max_queue_pairs * 2 +
> > > +		    virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ);
> > > +
> > > +	/* Allocate space for find_vqs parameters */
> > > +	vqs = kzalloc(total_vqs * sizeof(*vqs), GFP_KERNEL);
> > > +	callbacks = kzalloc(total_vqs * sizeof(*callbacks), GFP_KERNEL);
> > > +	if (!vqs || !callbacks)
> > > +		goto err_mem;
> > > +	names = kzalloc(total_vqs * sizeof(*names), GFP_KERNEL);
> > 
> > Why kzalloc? You seem to fill in all of it. Pls just use kmalloc
> > and initialize fields.
> > 
> 
> Right.
> > > +	if (!names)
> > > +		goto err_mem;
> > 
> > Since you have separate goto here it's more consistent
> > to use a separate label and two if tests above.
> > 
> 
> Sure.
> > > +
> > > +	/* Parameters for control virtqueue, if any */
> > > +	if (vi->has_cvq) {
> > > +		callbacks[total_vqs - 1] = NULL;
> > > +		names[total_vqs - 1] = kasprintf(GFP_KERNEL, "control");
> > > +	}
> > > 
> > > +	/* Allocate/initialize parameters for send/receive virtqueues */
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		callbacks[rxq2vq(i)] = skb_recv_done;
> > > +		callbacks[txq2vq(i)] = skb_xmit_done;
> > > +		names[rxq2vq(i)] = kasprintf(GFP_KERNEL, "input.%d", i);
> > > +		names[txq2vq(i)] = kasprintf(GFP_KERNEL, "output.%d", i);
> > > +	}
> > 
> > We would need to check kasprintf return value.
> 
> Looks like a better method is to make the name as a memeber of receive_queue 
> and send_queue, and use sprintf here.
> > Also if you allocate names from slab we'll need to free them
> > later.
> 
> Then it could be freed when the send_queue and receive_queue is freed.
> > It's probably easier to just use fixed names for now -
> > it's not like the index is really useful.
> 
> Looks useful for debugging e.g. check whether the irq distribution is as 
> expected.

Well it doesn't really matter which one goes where, right?
As long as interrupts are distributed well.

> > 
> > > +
> > > +	ret = vi->vdev->config->find_vqs(vi->vdev, total_vqs, vqs, callbacks,
> > > +					 (const char **)names);
> > 
> > Please avoid casts, use a proper type for names.
> 
> I'm consider we need a minor change in this api, we need allocate the names 
> dynamically which could not be a const char **.

I don't see why. Any use that allocates on the fly as
you did would leak memory. Any use like you suggest
e.g. allocating as part of send/receive structure
would be fine.

> > 
> > > +	if (ret)
> > > +		goto err_names;
> > > +
> > > +	if (vi->has_cvq) {
> > > +		vi->cvq = vqs[total_vqs - 1];
> > > 
> > >  		if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
> > >  		
> > >  			vi->dev->features |= NETIF_F_HW_VLAN_FILTER;
> > >  	
> > >  	}
> > > 
> > > +
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		vi->rq[i].vq = vqs[rxq2vq(i)];
> > > +		vi->sq[i].vq = vqs[txq2vq(i)];
> > > +	}
> > > +
> > > +	kfree(callbacks);
> > > +	kfree(vqs);
> > 
> > Who frees names if there's no error?
> > 
> 
> The virtio core does not copy the name, so it need this and only used for 
> debugging if I'm reading the code correctly.

No, virtio core does not free either individual vq name or the names
array passed in. So this leaks memory.

> > > +
> > > +	return 0;
> > > +
> > > +err_names:
> > > +	for (i = 0; i < total_vqs * 2; i++)
> > 
> > Why * 2?
> > This looks like a bug.
> 
> Yes, it's a bug.
> > 
> > > +		kfree(names[i]);
> > > +	kfree(names);
> > > +
> > > +err_mem:
> > > +	kfree(callbacks);
> > > +	kfree(vqs);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static int virtnet_alloc_queues(struct virtnet_info *vi)
> > > +{
> > > +	int i;
> > > +
> > > +	vi->sq = kzalloc(sizeof(vi->sq[0]) * vi->max_queue_pairs, GFP_KERNEL);
> > > +	vi->rq = kzalloc(sizeof(vi->rq[0]) * vi->max_queue_pairs, GFP_KERNEL);
> > 
> > While equivalent, *vi->rq is clearer IMHO.
> 
> Ok.
> > 
> > > +	if (!vi->rq || !vi->sq)
> > > +		goto err;
> > > +
> > > +	INIT_DELAYED_WORK(&vi->refill, refill_work);
> > > +	/* setup initial receive and send queue parameters */
> > 
> > Pls remove this comment, it's confuses more than it clarifies.
> 
> Sure.
> > 
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		vi->rq[i].pages = NULL;
> > > +		netif_napi_add(vi->dev, &vi->rq[i].napi, virtnet_poll,
> > > +			       napi_weight);
> > > +
> > > +		sg_init_table(vi->rq[i].sg, ARRAY_SIZE(vi->rq[i].sg));
> > > +		sg_init_table(vi->sq[i].sg, ARRAY_SIZE(vi->sq[i].sg));
> > > +	}
> > > +
> > > +
> > 
> > Extra empty line.
> > 
> 
> Will remove this line.
> > > +	return 0;
> > > +
> > > +err:
> > > +	virtnet_free_queues(vi);
> > > +	return -ENOMEM;
> > > +}
> > > +
> > > +static int init_vqs(struct virtnet_info *vi)
> > > +{
> > > +	int ret;
> > > +
> > > +	/* Allocate send & receive queues */
> > > +	ret = virtnet_alloc_queues(vi);
> > > +	if (ret)
> > > +		goto err;
> > > +
> > > +	ret = virtnet_find_vqs(vi);
> > > +	if (ret)
> > > +		goto err_free;
> > > +
> > > +	virtnet_set_affinity(vi, true);
> > > 
> > >  	return 0;
> > > 
> > > +
> > > +err_free:
> > > +	virtnet_free_queues(vi);
> > > +err:
> > > +	return ret;
> > > 
> > >  }
> > >  
> > >  static int virtnet_probe(struct virtio_device *vdev)
> > >  {
> > > 
> > > -	int err;
> > > +	int i, err;
> > > 
> > >  	struct net_device *dev;
> > >  	struct virtnet_info *vi;
> > > 
> > > +	u16 max_queue_pairs;
> > > +
> > > +	/* Find if host supports multiqueue virtio_net device */
> > > +	err = virtio_config_val(vdev, VIRTIO_NET_F_RFS,
> > > +				offsetof(struct virtio_net_config,
> > > +				max_virtqueue_pairs), &max_queue_pairs);
> > > +
> > > +	/* We need at least 2 queue's */
> > > +	if (err || max_queue_pairs < VIRTIO_NET_CTRL_RFS_VQ_PAIRS_MIN ||
> > > +	    max_queue_pairs > VIRTIO_NET_CTRL_RFS_VQ_PAIRS_MAX)
> > 
> > Check has_cvq as well.
> > 
> 
> Sure.
> > > +		max_queue_pairs = 1;
> > > 
> > >  	/* Allocate ourselves a network device with room for our info */
> > > 
> > > -	dev = alloc_etherdev(sizeof(struct virtnet_info));
> > > +	dev = alloc_etherdev_mq(sizeof(struct virtnet_info), max_queue_pairs);
> > > 
> > >  	if (!dev)
> > >  	
> > >  		return -ENOMEM;
> > > 
> > > @@ -1127,22 +1386,17 @@ static int virtnet_probe(struct virtio_device
> > > *vdev)> 
> > >  	/* Set up our device-specific information */
> > >  	vi = netdev_priv(dev);
> > > 
> > > -	netif_napi_add(dev, &vi->rq.napi, virtnet_poll, napi_weight);
> > > 
> > >  	vi->dev = dev;
> > >  	vi->vdev = vdev;
> > >  	vdev->priv = vi;
> > > 
> > > -	vi->rq.pages = NULL;
> > > 
> > >  	vi->stats = alloc_percpu(struct virtnet_stats);
> > >  	err = -ENOMEM;
> > >  	if (vi->stats == NULL)
> > >  	
> > >  		goto free;
> > > 
> > > -	INIT_DELAYED_WORK(&vi->refill, refill_work);
> > > 
> > >  	mutex_init(&vi->config_lock);
> > >  	vi->config_enable = true;
> > >  	INIT_WORK(&vi->config_work, virtnet_config_changed_work);
> > > 
> > > -	sg_init_table(vi->rq.sg, ARRAY_SIZE(vi->rq.sg));
> > > -	sg_init_table(vi->sq.sg, ARRAY_SIZE(vi->sq.sg));
> > > 
> > >  	/* If we can receive ANY GSO packets, we must allocate large ones. */
> > >  	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > > 
> > > @@ -1153,10 +1407,21 @@ static int virtnet_probe(struct virtio_device
> > > *vdev)> 
> > >  	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
> > >  	
> > >  		vi->mergeable_rx_bufs = true;
> > > 
> > > +	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> > > +		vi->has_cvq = true;
> > > +
> > > +	/* Use single tx/rx queue pair as default */
> > > +	vi->curr_queue_pairs = 1;
> > > +	vi->max_queue_pairs = max_queue_pairs;
> > > +
> > > +	/* Allocate/initialize the rx/tx queues, and invoke find_vqs */
> > > 
> > >  	err = init_vqs(vi);
> > >  	if (err)
> > >  	
> > >  		goto free_stats;
> > > 
> > > +	netif_set_real_num_tx_queues(dev, 1);
> > > +	netif_set_real_num_rx_queues(dev, 1);
> > > +
> > > 
> > >  	err = register_netdev(dev);
> > >  	if (err) {
> > >  	
> > >  		pr_debug("virtio_net: registering device failed\n");
> > > 
> > > @@ -1164,12 +1429,15 @@ static int virtnet_probe(struct virtio_device
> > > *vdev)> 
> > >  	}
> > >  	
> > >  	/* Last of all, set up some receive buffers. */
> > > 
> > > -	try_fill_recv(&vi->rq, GFP_KERNEL);
> > > -
> > > -	/* If we didn't even get one input buffer, we're useless. */
> > > -	if (vi->rq.num == 0) {
> > > -		err = -ENOMEM;
> > > -		goto unregister;
> > > +	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +		try_fill_recv(&vi->rq[i], GFP_KERNEL);
> > > +
> > > +		/* If we didn't even get one input buffer, we're useless. */
> > > +		if (vi->rq[i].num == 0) {
> > > +			free_unused_bufs(vi);
> > > +			err = -ENOMEM;
> > > +			goto free_recv_bufs;
> > > +		}
> > > 
> > >  	}
> > >  	
> > >  	/* Assume link up if device can't report link status,
> > > 
> > > @@ -1182,13 +1450,19 @@ static int virtnet_probe(struct virtio_device
> > > *vdev)> 
> > >  		netif_carrier_on(dev);
> > >  	
> > >  	}
> > > 
> > > -	pr_debug("virtnet: registered device %s\n", dev->name);
> > > +	pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
> > > +		 dev->name, max_queue_pairs);
> > > +
> > > 
> > >  	return 0;
> > > 
> > > -unregister:
> > > +free_recv_bufs:
> > > +	free_receive_bufs(vi);
> > > 
> > >  	unregister_netdev(dev);
> > > 
> > > +
> > > 
> > >  free_vqs:
> > > -	vdev->config->del_vqs(vdev);
> > > +	cancel_delayed_work_sync(&vi->refill);
> > > +	virtnet_del_vqs(vi);
> > > +
> > > 
> > >  free_stats:
> > >  	free_percpu(vi->stats);
> > >  
> > >  free:
> > > @@ -1196,28 +1470,6 @@ free:
> > >  	return err;
> > >  
> > >  }
> > > 
> > > -static void free_unused_bufs(struct virtnet_info *vi)
> > > -{
> > > -	void *buf;
> > > -	while (1) {
> > > -		buf = virtqueue_detach_unused_buf(vi->sq.vq);
> > > -		if (!buf)
> > > -			break;
> > > -		dev_kfree_skb(buf);
> > > -	}
> > > -	while (1) {
> > > -		buf = virtqueue_detach_unused_buf(vi->rq.vq);
> > > -		if (!buf)
> > > -			break;
> > > -		if (vi->mergeable_rx_bufs || vi->big_packets)
> > > -			give_pages(&vi->rq, buf);
> > > -		else
> > > -			dev_kfree_skb(buf);
> > > -		--vi->rq.num;
> > > -	}
> > > -	BUG_ON(vi->rq.num != 0);
> > > -}
> > > -
> > > 
> > >  static void remove_vq_common(struct virtnet_info *vi)
> > >  {
> > >  
> > >  	vi->vdev->config->reset(vi->vdev);
> > > 
> > > @@ -1225,10 +1477,9 @@ static void remove_vq_common(struct virtnet_info
> > > *vi)> 
> > >  	/* Free unused buffers in both send and recv, if any. */
> > >  	free_unused_bufs(vi);
> > > 
> > > -	vi->vdev->config->del_vqs(vi->vdev);
> > > +	free_receive_bufs(vi);
> > > 
> > > -	while (vi->rq.pages)
> > > -		__free_pages(get_a_page(&vi->rq, GFP_KERNEL), 0);
> > > +	virtnet_del_vqs(vi);
> > > 
> > >  }
> > >  
> > >  static void __devexit virtnet_remove(struct virtio_device *vdev)
> > > 
> > > @@ -1254,6 +1505,7 @@ static void __devexit virtnet_remove(struct
> > > virtio_device *vdev)> 
> > >  static int virtnet_freeze(struct virtio_device *vdev)
> > >  {
> > >  
> > >  	struct virtnet_info *vi = vdev->priv;
> > > 
> > > +	int i;
> > > 
> > >  	/* Prevent config work handler from accessing the device */
> > >  	mutex_lock(&vi->config_lock);
> > > 
> > > @@ -1264,7 +1516,10 @@ static int virtnet_freeze(struct virtio_device
> > > *vdev)> 
> > >  	cancel_delayed_work_sync(&vi->refill);
> > >  	
> > >  	if (netif_running(vi->dev))
> > > 
> > > -		napi_disable(&vi->rq.napi);
> > > +		for (i = 0; i < vi->max_queue_pairs; i++) {
> > > +			napi_disable(&vi->rq[i].napi);
> > > +			netif_napi_del(&vi->rq[i].napi);
> > > +		}
> > > 
> > >  	remove_vq_common(vi);
> > > 
> > > @@ -1276,24 +1531,29 @@ static int virtnet_freeze(struct virtio_device
> > > *vdev)> 
> > >  static int virtnet_restore(struct virtio_device *vdev)
> > >  {
> > >  
> > >  	struct virtnet_info *vi = vdev->priv;
> > > 
> > > -	int err;
> > > +	int err, i;
> > > 
> > >  	err = init_vqs(vi);
> > >  	if (err)
> > >  	
> > >  		return err;
> > >  	
> > >  	if (netif_running(vi->dev))
> > > 
> > > -		virtnet_napi_enable(&vi->rq);
> > > +		for (i = 0; i < vi->max_queue_pairs; i++)
> > > +			virtnet_napi_enable(&vi->rq[i]);
> > > 
> > >  	netif_device_attach(vi->dev);
> > > 
> > > -	if (!try_fill_recv(&vi->rq, GFP_KERNEL))
> > > -		schedule_delayed_work(&vi->refill, 0);
> > > +	for (i = 0; i < vi->max_queue_pairs; i++)
> > > +		if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
> > > +			schedule_delayed_work(&vi->refill, 0);
> > > 
> > >  	mutex_lock(&vi->config_lock);
> > >  	vi->config_enable = true;
> > >  	mutex_unlock(&vi->config_lock);
> > > 
> > > +	if (vi->has_cvq && virtio_has_feature(vi->vdev, VIRTIO_NET_F_RFS))
> > > +		virtnet_set_queues(vi);
> > > +
> > 
> > I think it's easier to test
> > if (curr_queue_pairs == max_queue_pairs)
> > within virtnet_set_queues and make it
> > a NOP if so.
> 
> Still need to send the command during restore since we reset the device during 
> freezing.

Then maybe check vi->has_cvq && virtio_has_feature(vi->vdev,
VIRTIO_NET_F_RFS) in there?

> > 
> > >  	return 0;
> > >  
> > >  }
> > >  #endif
> > > 
> > > @@ -1311,7 +1571,7 @@ static unsigned int features[] = {
> > > 
> > >  	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
> > >  	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
> > >  	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
> > > 
> > > -	VIRTIO_NET_F_GUEST_ANNOUNCE,
> > > +	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_RFS,
> > > 
> > >  };
> > >  
> > >  static struct virtio_driver virtio_net_driver = {
> > > 
> > > @@ -1329,6 +1589,12 @@ static struct virtio_driver virtio_net_driver = {
> > > 
> > >  #endif
> > >  };
> > > 
> > > +static const struct ethtool_ops virtnet_ethtool_ops = {
> > > +	.get_drvinfo = virtnet_get_drvinfo,
> > > +	.get_link = ethtool_op_get_link,
> > > +	.get_ringparam = virtnet_get_ringparam,
> > > +};
> > > +
> > > 
> > >  static int __init init(void)
> > >  {
> > >  
> > >  	return register_virtio_driver(&virtio_net_driver);
> > > 
> > > diff --git a/include/uapi/linux/virtio_net.h
> > > b/include/uapi/linux/virtio_net.h index 2470f54..6056cec 100644
> > > --- a/include/uapi/linux/virtio_net.h
> > > +++ b/include/uapi/linux/virtio_net.h
> > > @@ -51,6 +51,7 @@
> > > 
> > >  #define VIRTIO_NET_F_CTRL_RX_EXTRA 20	/* Extra RX mode control support 
> */
> > >  #define VIRTIO_NET_F_GUEST_ANNOUNCE 21	/* Guest can announce device on
> > >  the
> > >  
> > >  					 * network */
> > > 
> > > +#define VIRTIO_NET_F_RFS	22	/* Device supports multiple TXQ/RXQ */
> > 
> > Should be
> > /* Device supports Receive Flow Steering. */
> 
> Ok.
> > 
> > >  #define VIRTIO_NET_S_LINK_UP	1	/* Link is up */
> > >  #define VIRTIO_NET_S_ANNOUNCE	2	/* Announcement is needed */
> > > 
> > > @@ -60,6 +61,8 @@ struct virtio_net_config {
> > > 
> > >  	__u8 mac[6];
> > >  	/* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
> > >  	__u16 status;
> > > 
> > > +	/* Total number of RX/TX queues */
> > 
> > Better comment:
> > /* Maximum number of each of transmit and receive queues;
> >  * see VIRTIO_NET_F_RFS and VIRTIO_NET_CTRL_RFS.
> >  * Legal values are between 1 and 0x8000
> >  */
> 
> Sure.
> > 
> > > +	__u16 max_virtqueue_pairs;
> > > 
> > >  } __attribute__((packed));
> > >  
> > >  /* This is the first element of the scatter-gather list.  If you don't
> > > 
> > > @@ -166,4 +169,17 @@ struct virtio_net_ctrl_mac {
> > > 
> > >  #define VIRTIO_NET_CTRL_ANNOUNCE       3
> > >  
> > >   #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0
> > > 
> > > +/*
> > > + * Control multiqueue
> > 
> > Here's a better comment:
> > 
> > Control Receive Flow Steering
> > 
> >  The command VIRTIO_NET_CTRL_RFS_VQ_PAIRS_SET
> >  enables Receive Flow Steering, specifying the number of the transmit and
> > receive queues that will be used.
> >  After the command is consumed and acked by the device,
> >  the device will not steer new packets on receive virtqueues
> >  other than specified nor read from transmit virtqueues other than
> > specified. Accordingly, driver should not transmit new packets
> >  on virtqueues other than specified.
> > 
> 
> Sure, thanks for the this reminding.
> > > + *
> > 
> > Remove this empty line.
> 
> Ok.
> > 
> > > + */
> > > +struct virtio_net_ctrl_rfs {
> > 
> > /* Number of each of transmit and receive queues to use;
> >  * Legal values are between 1 and max_virtqueue_pairs
> >  */
> > 
> > > +	u16 virtqueue_pairs;
> > > +};
> > > +
> > > +#define VIRTIO_NET_CTRL_RFS   4
> > > + #define VIRTIO_NET_CTRL_RFS_VQ_PAIRS_SET        0
> > 
> > /* Value range for max_virtqueue_pairsfor and virtqueue_pairs above */
> > 
> > > + #define VIRTIO_NET_CTRL_RFS_VQ_PAIRS_MIN        1
> > > + #define VIRTIO_NET_CTRL_RFS_VQ_PAIRS_MAX        0x8000
> > > +
> > > 
> > >  #endif /* _LINUX_VIRTIO_NET_H */
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe kvm" in
> > the body of a message to [email-masked]
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html