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Date:   Fri, 18 Nov 2022 04:18:35 +0000
From:   Bobby Eshleman <bobbyeshleman@gmail.com>
To:     Stefano Garzarella <sgarzare@redhat.com>
Cc:     Bobby Eshleman <bobby.eshleman@gmail.com>,
        Cong Wang <cong.wang@bytedance.com>,
        Bobby Eshleman <bobby.eshleman@bytedance.com>,
        Jiang Wang <jiang.wang@bytedance.com>,
        "Michael S. Tsirkin" <mst@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        Eric Dumazet <edumazet@google.com>,
        Stefan Hajnoczi <stefanha@redhat.com>, kvm@vger.kernel.org,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v3] virtio/vsock: replace virtio_vsock_pkt with sk_buff
Message-ID: <Y3cHcnu1lMijmMJM@bullseye>
References: <20221110171723.24263-1-bobby.eshleman@bytedance.com>
 <20221111122411.p2tntjcuvdqcpa5b@sgarzare-redhat>
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In-Reply-To: <20221111122411.p2tntjcuvdqcpa5b@sgarzare-redhat>
Precedence: bulk

On Fri, Nov 11, 2022 at 01:24:11PM +0100, Stefano Garzarella wrote:
> On Thu, Nov 10, 2022 at 09:17:22AM -0800, Bobby Eshleman wrote:
> > This commit changes virtio/vsock to use sk_buff instead of
> > virtio_vsock_pkt. Beyond better conforming to other net code, using
> > sk_buff allows vsock to use sk_buff-dependent features in the future
> > (such as sockmap) and improves throughput.
> > 
> > This patch introduces the following performance changes:
> > 
> > Tool/Config: uperf w/ 64 threads, SOCK_STREAM
> > Test Runs: 5, mean of results
> > Before: commit 95ec6bce2a0b ("Merge branch 'net-ipa-more-endpoints'")
> > 
> > Test: 64KB, g2h
> > Before: 21.63 Gb/s
> > After: 25.59 Gb/s (+18%)
> > 
> > Test: 16B, g2h
> > Before: 11.86 Mb/s
> > After: 17.41 Mb/s (+46%)
> > 
> > Test: 64KB, h2g
> > Before: 2.15 Gb/s
> > After: 3.6 Gb/s (+67%)
> > 
> > Test: 16B, h2g
> > Before: 14.38 Mb/s
> > After: 18.43 Mb/s (+28%)
> 
> Nice, thanks for attaching perf numbers!
> 
> I see similar variation also with iperf-vsock, but higher absolute values, I
> think because of the different hardware or maybe because you're using nested
> VMs.
> 
> We have some regression (not because of this patch) in the h2g scenario, it
> would be interesting to investigate. (I'll try next week)
> When I did some performance analysis h2g was slower, because the host has to
> split the packet according to the guest buffer (4K), while the guest can
> queue the whole buffer, but not as much:
> https://lore.kernel.org/lkml/20190730154334.237789-1-sgarzare@redhat.com/
> 

This makes sense.

> > 
> > Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
> 
> checkpatch prints this warning, maybe you should fix the setup:
> 
> $ ./scripts/checkpatch.pl --strict -g  HEAD~1..HEAD
> WARNING: From:/Signed-off-by: email address mismatch: 'From: Bobby Eshleman
> <bobby.eshleman@gmail.com>' != 'Signed-off-by: Bobby Eshleman
> <bobby.eshleman@bytedance.com>'
> 
> > ---
> > Changes in v3:
> > - fix seqpacket bug
> > - use zero in vhost_add_used(..., 0) device doesn't write to
> > buffer
> > - use xmas tree style declarations
> > - vsock_hdr() -> virtio_vsock_hdr() and other include file style fixes
> > - no skb merging
> > - save space by not using vsock_metadata
> >    - use _skb_refdst instead of skb buffer space for flags
> >    - use skb_pull() to keep track of read bytes instead of
> >      using an an extra variable 'off' in the skb buffer space
> > - remove unnecessary sk_allocation assignment
> > - do not zero hdr needlessly
> > - introduce virtio_transport_skb_len() because skb->len changes now
> > - use spin_lock() directly on queue lock instead of sk_buff_head helpers
> >  which use spin_lock_irqsave() (e.g., skb_dequeue)
> > - do not reduce buffer size to be page size divisible
> > - Note: the biggest performance change came from loosening the spinlock
> >  variation and not reducing the buffer size.
> 
> I was going to ask that, thanks for bringing it forward! :-)
> 
> So it was spin_lock_irqsave vs spin_lock_bh, right?
> 

Yep. I've got access to a better system to test this just week, so I'm
got to test some theories as to why (nesting may require
trap-and-emulate for the IRQ enable/disable register?). If anyone has
some insights into why the save/restore lock variants would cause such a
perf hit, I'd love to hear it.

> > 
> > Changes in v2:
> > - Use alloc_skb() directly instead of sock_alloc_send_pskb() to minimize
> >  uAPI changes.
> > - Do not marshal errors to -ENOMEM for non-virtio implementations.
> > - No longer a part of the original series
> > - Some code cleanup and refactoring
> > - Include performance stats
> > 
> > drivers/vhost/vsock.c                   | 222 +++++-------
> > include/linux/virtio_vsock.h            |  99 +++--
> > net/vmw_vsock/virtio_transport.c        | 160 ++++-----
> > net/vmw_vsock/virtio_transport_common.c | 458 ++++++++++++------------
> > net/vmw_vsock/vsock_loopback.c          |  51 +--
> > 5 files changed, 477 insertions(+), 513 deletions(-)
> > 
> > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> > index 5703775af129..cf6b67154072 100644
> > --- a/drivers/vhost/vsock.c
> > +++ b/drivers/vhost/vsock.c
> > @@ -51,8 +51,7 @@ struct vhost_vsock {
> > 	struct hlist_node hash;
> > 
> > 	struct vhost_work send_pkt_work;
> > -	spinlock_t send_pkt_list_lock;
> > -	struct list_head send_pkt_list;	/* host->guest pending packets */
> > +	struct sk_buff_head send_pkt_queue; /* host->guest pending packets */
> > 
> > 	atomic_t queued_replies;
> > 
> > @@ -108,40 +107,37 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> > 	vhost_disable_notify(&vsock->dev, vq);
> > 
> > 	do {
> > -		struct virtio_vsock_pkt *pkt;
> > +		struct virtio_vsock_hdr *hdr;
> > +		size_t iov_len, payload_len;
> > 		struct iov_iter iov_iter;
> > +		u32 flags_to_restore = 0;
> > +		struct sk_buff *skb;
> > 		unsigned out, in;
> > 		size_t nbytes;
> > -		size_t iov_len, payload_len;
> > 		int head;
> > -		u32 flags_to_restore = 0;
> > 
> > -		spin_lock_bh(&vsock->send_pkt_list_lock);
> > -		if (list_empty(&vsock->send_pkt_list)) {
> > -			spin_unlock_bh(&vsock->send_pkt_list_lock);
> > +		spin_lock(&vsock->send_pkt_queue.lock);
> 
> Could we continue to use spin_lock_bh()?
> 
> The scenario hasn't changed, we have workqueue/tasklet vs user context and
> looking at "Table of Minimum Requirements" in kernel-hacking/locking.rst, it
> seems to be okay to use it.
> 

Sure thing. Just for my own learning, may I ask where is this lock
acquired in a tasklet? I could only find tasklet usage in vmci.

> Perhaps we could add our helpers for queue_head, queue_tail, and dequeue.
> 

To linux/skbuff.h or to linux/virtio_vsock.h?

> > +		skb = __skb_dequeue(&vsock->send_pkt_queue);
> > +		spin_unlock(&vsock->send_pkt_queue.lock);
> > +
> > +		if (!skb) {
> > 			vhost_enable_notify(&vsock->dev, vq);
> > 			break;
> > 		}
> > 
> > -		pkt = list_first_entry(&vsock->send_pkt_list,
> > -				       struct virtio_vsock_pkt, list);
> > -		list_del_init(&pkt->list);
> > -		spin_unlock_bh(&vsock->send_pkt_list_lock);
> > -
> > 		head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
> > 					 &out, &in, NULL, NULL);
> > 		if (head < 0) {
> > -			spin_lock_bh(&vsock->send_pkt_list_lock);
> > -			list_add(&pkt->list, &vsock->send_pkt_list);
> > -			spin_unlock_bh(&vsock->send_pkt_list_lock);
> > +			spin_lock(&vsock->send_pkt_queue.lock);
> > +			__skb_queue_head(&vsock->send_pkt_queue, skb);
> > +			spin_unlock(&vsock->send_pkt_queue.lock);
> > 			break;
> > 		}
> > 
> > 		if (head == vq->num) {
> > -			spin_lock_bh(&vsock->send_pkt_list_lock);
> > -			list_add(&pkt->list, &vsock->send_pkt_list);
> > -			spin_unlock_bh(&vsock->send_pkt_list_lock);
> > -
> > +			spin_lock(&vsock->send_pkt_queue.lock);
> > +			__skb_queue_head(&vsock->send_pkt_queue, skb);
> > +			spin_unlock(&vsock->send_pkt_queue.lock);
> > 			/* We cannot finish yet if more buffers snuck in while
> > 			 * re-enabling notify.
> > 			 */
> > @@ -153,26 +149,27 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> > 		}
> > 
> > 		if (out) {
> > -			virtio_transport_free_pkt(pkt);
> > +			virtio_vsock_kfree_skb(skb);
> > 			vq_err(vq, "Expected 0 output buffers, got %u\n", out);
> > 			break;
> > 		}
> > 
> > 		iov_len = iov_length(&vq->iov[out], in);
> > -		if (iov_len < sizeof(pkt->hdr)) {
> > -			virtio_transport_free_pkt(pkt);
> > +		if (iov_len < sizeof(*hdr)) {
> > +			virtio_vsock_kfree_skb(skb);
> > 			vq_err(vq, "Buffer len [%zu] too small\n", iov_len);
> > 			break;
> > 		}
> > 
> > 		iov_iter_init(&iov_iter, READ, &vq->iov[out], in, iov_len);
> > -		payload_len = pkt->len - pkt->off;
> > +		payload_len = skb->len;
> > +		hdr = virtio_vsock_hdr(skb);
> > 
> > 		/* If the packet is greater than the space available in the
> > 		 * buffer, we split it using multiple buffers.
> > 		 */
> > -		if (payload_len > iov_len - sizeof(pkt->hdr)) {
> > -			payload_len = iov_len - sizeof(pkt->hdr);
> > +		if (payload_len > iov_len - sizeof(*hdr)) {
> > +			payload_len = iov_len - sizeof(*hdr);
> > 
> > 			/* As we are copying pieces of large packet's 			buffer to
> > 			 * small rx buffers, headers of packets in rx queue are
> > @@ -185,31 +182,30 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> > 			 * bits set. After initialized header will be 			 copied to
> > 			 * rx buffer, these required bits will be restored.
> > 			 */
> > -			if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
> > -				pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> > +			if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
> > +				hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> > 				flags_to_restore |= VIRTIO_VSOCK_SEQ_EOM;
> > 
> > -				if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR) {
> > -					pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> > +				if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR) {
> > +					hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> > 					flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR;
> > 				}
> > 			}
> > 		}
> > 
> > 		/* Set the correct length in the header */
> > -		pkt->hdr.len = cpu_to_le32(payload_len);
> > +		hdr->len = cpu_to_le32(payload_len);
> > 
> > -		nbytes = copy_to_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
> > -		if (nbytes != sizeof(pkt->hdr)) {
> > -			virtio_transport_free_pkt(pkt);
> > +		nbytes = copy_to_iter(hdr, sizeof(*hdr), &iov_iter);
> > +		if (nbytes != sizeof(*hdr)) {
> > +			virtio_vsock_kfree_skb(skb);
> > 			vq_err(vq, "Faulted on copying pkt hdr\n");
> > 			break;
> > 		}
> > 
> > -		nbytes = copy_to_iter(pkt->buf + pkt->off, payload_len,
> > -				      &iov_iter);
> > +		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
> > 		if (nbytes != payload_len) {
> > -			virtio_transport_free_pkt(pkt);
> > +			virtio_vsock_kfree_skb(skb);
> > 			vq_err(vq, "Faulted on copying pkt buf\n");
> > 			break;
> > 		}
> > @@ -217,31 +213,30 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> > 		/* Deliver to monitoring devices all packets that we
> > 		 * will transmit.
> > 		 */
> > -		virtio_transport_deliver_tap_pkt(pkt);
> > +		virtio_transport_deliver_tap_pkt(skb);
> > 
> > -		vhost_add_used(vq, head, sizeof(pkt->hdr) + payload_len);
> > +		vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
> > 		added = true;
> > 
> > -		pkt->off += payload_len;
> > +		skb_pull(skb, payload_len);
> > 		total_len += payload_len;
> > 
> > 		/* If we didn't send all the payload we can requeue the packet
> > 		 * to send it with the next available buffer.
> > 		 */
> > -		if (pkt->off < pkt->len) {
> > -			pkt->hdr.flags |= cpu_to_le32(flags_to_restore);
> > +		if (skb->len > 0) {
> > +			hdr->flags |= cpu_to_le32(flags_to_restore);
> > 
> > -			/* We are queueing the same virtio_vsock_pkt to handle
> > +			/* We are queueing the same skb to handle
> > 			 * the remaining bytes, and we want to deliver it
> > 			 * to monitoring devices in the next iteration.
> > 			 */
> > -			pkt->tap_delivered = false;
> > -
> > -			spin_lock_bh(&vsock->send_pkt_list_lock);
> > -			list_add(&pkt->list, &vsock->send_pkt_list);
> > -			spin_unlock_bh(&vsock->send_pkt_list_lock);
> > +			virtio_vsock_skb_clear_tap_delivered(skb);
> > +			spin_lock(&vsock->send_pkt_queue.lock);
> > +			__skb_queue_head(&vsock->send_pkt_queue, skb);
> > +			spin_unlock(&vsock->send_pkt_queue.lock);
> > 		} else {
> > -			if (pkt->reply) {
> > +			if (virtio_vsock_skb_reply(skb)) {
> > 				int val;
> > 
> > 				val = atomic_dec_return(&vsock->queued_replies);
> > @@ -253,7 +248,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> > 					restart_tx = true;
> > 			}
> > 
> > -			virtio_transport_free_pkt(pkt);
> > +			virtio_vsock_consume_skb(skb);
> > 		}
> > 	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
> > 	if (added)
> > @@ -278,28 +273,28 @@ static void vhost_transport_send_pkt_work(struct vhost_work *work)
> > }
> > 
> > static int
> > -vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt)
> > +vhost_transport_send_pkt(struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct vhost_vsock *vsock;
> > -	int len = pkt->len;
> > +	int len = skb->len;
> > 
> > 	rcu_read_lock();
> > 
> > 	/* Find the vhost_vsock according to guest context id  */
> > -	vsock = vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid));
> > +	vsock = vhost_vsock_get(le64_to_cpu(hdr->dst_cid));
> > 	if (!vsock) {
> > 		rcu_read_unlock();
> > -		virtio_transport_free_pkt(pkt);
> > +		virtio_vsock_kfree_skb(skb);
> > 		return -ENODEV;
> > 	}
> > 
> > -	if (pkt->reply)
> > +	if (virtio_vsock_skb_reply(skb))
> > 		atomic_inc(&vsock->queued_replies);
> > 
> > -	spin_lock_bh(&vsock->send_pkt_list_lock);
> > -	list_add_tail(&pkt->list, &vsock->send_pkt_list);
> > -	spin_unlock_bh(&vsock->send_pkt_list_lock);
> > -
> > +	spin_lock(&vsock->send_pkt_queue.lock);
> 
> 
> 
> > +	__skb_queue_tail(&vsock->send_pkt_queue, skb);
> > +	spin_unlock(&vsock->send_pkt_queue.lock);
> > 	vhost_work_queue(&vsock->dev, &vsock->send_pkt_work);
> > 
> > 	rcu_read_unlock();
> > @@ -310,10 +305,8 @@ static int
> > vhost_transport_cancel_pkt(struct vsock_sock *vsk)
> > {
> > 	struct vhost_vsock *vsock;
> > -	struct virtio_vsock_pkt *pkt, *n;
> > 	int cnt = 0;
> > 	int ret = -ENODEV;
> > -	LIST_HEAD(freeme);
> > 
> > 	rcu_read_lock();
> > 
> > @@ -322,20 +315,7 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
> > 	if (!vsock)
> > 		goto out;
> > 
> > -	spin_lock_bh(&vsock->send_pkt_list_lock);
> > -	list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) {
> > -		if (pkt->vsk != vsk)
> > -			continue;
> > -		list_move(&pkt->list, &freeme);
> > -	}
> > -	spin_unlock_bh(&vsock->send_pkt_list_lock);
> > -
> > -	list_for_each_entry_safe(pkt, n, &freeme, list) {
> > -		if (pkt->reply)
> > -			cnt++;
> > -		list_del(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > -	}
> > +	cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
> > 
> > 	if (cnt) {
> > 		struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
> > @@ -352,12 +332,14 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
> > 	return ret;
> > }
> > 
> > -static struct virtio_vsock_pkt *
> > -vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
> > +static struct sk_buff *
> > +vhost_vsock_alloc_skb(struct vhost_virtqueue *vq,
> > 		      unsigned int out, unsigned int in)
> > {
> > -	struct virtio_vsock_pkt *pkt;
> > +	struct virtio_vsock_hdr *hdr;
> > 	struct iov_iter iov_iter;
> > +	struct sk_buff *skb;
> > +	size_t payload_len;
> > 	size_t nbytes;
> > 	size_t len;
> > 
> > @@ -366,50 +348,48 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
> > 		return NULL;
> > 	}
> > 
> > -	pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
> > -	if (!pkt)
> > +	len = iov_length(vq->iov, out);
> > +
> > +	/* len contains both payload and hdr */
> > +	skb = alloc_skb(len, GFP_KERNEL);
> > +	if (!skb)
> > 		return NULL;
> > 
> > -	len = iov_length(vq->iov, out);
> > +	skb_reserve(skb, VIRTIO_VSOCK_SKB_HEADROOM);
> 
> What about a virtio_vsock_alloc_skb() where we call alloc_skb() and
> skb_reserve()?
> 
> Then we can reuse it in all the places where we allocate the skb.

I think that makes sense.

> 
> > 	iov_iter_init(&iov_iter, WRITE, vq->iov, out, len);
> > 
> > -	nbytes = copy_from_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
> > -	if (nbytes != sizeof(pkt->hdr)) {
> > +	hdr = virtio_vsock_hdr(skb);
> > +	nbytes = copy_from_iter(hdr, sizeof(*hdr), &iov_iter);
> > +	if (nbytes != sizeof(*hdr)) {
> > 		vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n",
> > -		       sizeof(pkt->hdr), nbytes);
> > -		kfree(pkt);
> > +		       sizeof(*hdr), nbytes);
> > +		virtio_vsock_kfree_skb(skb);
> > 		return NULL;
> > 	}
> > 
> > -	pkt->len = le32_to_cpu(pkt->hdr.len);
> > +	payload_len = le32_to_cpu(hdr->len);
> > 
> > 	/* No payload */
> > -	if (!pkt->len)
> > -		return pkt;
> > +	if (!payload_len)
> > +		return skb;
> > 
> > 	/* The pkt is too big */
> > -	if (pkt->len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
> > -		kfree(pkt);
> > +	if (payload_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
> > +		virtio_vsock_kfree_skb(skb);
> > 		return NULL;
> > 	}
> > 
> > -	pkt->buf = kvmalloc(pkt->len, GFP_KERNEL);
> > -	if (!pkt->buf) {
> > -		kfree(pkt);
> > -		return NULL;
> > -	}
> > +	virtio_vsock_skb_rx_put(skb);
> > 
> > -	pkt->buf_len = pkt->len;
> > -
> > -	nbytes = copy_from_iter(pkt->buf, pkt->len, &iov_iter);
> > -	if (nbytes != pkt->len) {
> > -		vq_err(vq, "Expected %u byte payload, got %zu bytes\n",
> > -		       pkt->len, nbytes);
> > -		virtio_transport_free_pkt(pkt);
> > +	nbytes = copy_from_iter(skb->data, payload_len, &iov_iter);
> > +	if (nbytes != payload_len) {
> > +		vq_err(vq, "Expected %zu byte payload, got %zu bytes\n",
> > +		       payload_len, nbytes);
> > +		virtio_vsock_kfree_skb(skb);
> > 		return NULL;
> > 	}
> > 
> > -	return pkt;
> > +	return skb;
> > }
> > 
> > /* Is there space left for replies to rx packets? */
> > @@ -496,9 +476,9 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
> > 						  poll.work);
> > 	struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
> > 						 dev);
> > -	struct virtio_vsock_pkt *pkt;
> > 	int head, pkts = 0, total_len = 0;
> > 	unsigned int out, in;
> > +	struct sk_buff *skb;
> > 	bool added = false;
> > 
> > 	mutex_lock(&vq->mutex);
> > @@ -511,6 +491,8 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
> > 
> > 	vhost_disable_notify(&vsock->dev, vq);
> > 	do {
> > +		struct virtio_vsock_hdr *hdr;
> > +
> > 		if (!vhost_vsock_more_replies(vsock)) {
> > 			/* Stop tx until the device processes already
> > 			 * pending replies.  Leave tx virtqueue
> > @@ -532,24 +514,26 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
> > 			break;
> > 		}
> > 
> > -		pkt = vhost_vsock_alloc_pkt(vq, out, in);
> > -		if (!pkt) {
> > +		skb = vhost_vsock_alloc_skb(vq, out, in);
> > +		if (!skb) {
> > 			vq_err(vq, "Faulted on pkt\n");
> > 			continue;
> > 		}
> > 
> > -		total_len += sizeof(pkt->hdr) + pkt->len;
> > +		total_len += sizeof(*hdr) + skb->len;
> > 
> > 		/* Deliver to monitoring devices all received packets */
> > -		virtio_transport_deliver_tap_pkt(pkt);
> > +		virtio_transport_deliver_tap_pkt(skb);
> > +
> > +		hdr = virtio_vsock_hdr(skb);
> > 
> > 		/* Only accept correctly addressed packets */
> > -		if (le64_to_cpu(pkt->hdr.src_cid) == vsock->guest_cid &&
> > -		    le64_to_cpu(pkt->hdr.dst_cid) ==
> > +		if (le64_to_cpu(hdr->src_cid) == vsock->guest_cid &&
> > +		    le64_to_cpu(hdr->dst_cid) ==
> > 		    vhost_transport_get_local_cid())
> > -			virtio_transport_recv_pkt(&vhost_transport, pkt);
> > +			virtio_transport_recv_pkt(&vhost_transport, skb);
> > 		else
> > -			virtio_transport_free_pkt(pkt);
> > +			virtio_vsock_kfree_skb(skb);
> > 
> > 		vhost_add_used(vq, head, 0);
> > 		added = true;
> > @@ -693,8 +677,7 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
> > 		       VHOST_VSOCK_WEIGHT, true, NULL);
> > 
> > 	file->private_data = vsock;
> > -	spin_lock_init(&vsock->send_pkt_list_lock);
> > -	INIT_LIST_HEAD(&vsock->send_pkt_list);
> > +	skb_queue_head_init(&vsock->send_pkt_queue);
> > 	vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
> > 	return 0;
> > 
> > @@ -760,16 +743,7 @@ static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
> > 	vhost_vsock_flush(vsock);
> > 	vhost_dev_stop(&vsock->dev);
> > 
> > -	spin_lock_bh(&vsock->send_pkt_list_lock);
> > -	while (!list_empty(&vsock->send_pkt_list)) {
> > -		struct virtio_vsock_pkt *pkt;
> > -
> > -		pkt = list_first_entry(&vsock->send_pkt_list,
> > -				struct virtio_vsock_pkt, list);
> > -		list_del_init(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > -	}
> > -	spin_unlock_bh(&vsock->send_pkt_list_lock);
> > +	virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
> > 
> > 	vhost_dev_cleanup(&vsock->dev);
> > 	kfree(vsock->dev.vqs);
> > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> > index 35d7eedb5e8e..17e1cb8c91b2 100644
> > --- a/include/linux/virtio_vsock.h
> > +++ b/include/linux/virtio_vsock.h
> > @@ -4,9 +4,82 @@
> > 
> > #include <uapi/linux/virtio_vsock.h>
> > #include <linux/socket.h>
> > +#include <vdso/bits.h>
> > #include <net/sock.h>
> > #include <net/af_vsock.h>
> > 
> > +#define VIRTIO_VSOCK_SKB_HEADROOM (sizeof(struct virtio_vsock_hdr))
> > +
> > +enum virtio_vsock_skb_flags {
> > +	VIRTIO_VSOCK_SKB_FLAGS_REPLY		= BIT(0),
> > +	VIRTIO_VSOCK_SKB_FLAGS_TAP_DELIVERED	= BIT(1),
> > +};
> > +
> > +static inline struct virtio_vsock_hdr *virtio_vsock_hdr(struct sk_buff *skb)
> > +{
> > +	return (struct virtio_vsock_hdr *)skb->head;
> > +}
> > +
> > +static inline bool virtio_vsock_skb_reply(struct sk_buff *skb)
> > +{
> > +	return skb->_skb_refdst & VIRTIO_VSOCK_SKB_FLAGS_REPLY;
> > +}
> > +
> > +static inline void virtio_vsock_skb_set_reply(struct sk_buff *skb)
> > +{
> > +	skb->_skb_refdst |= VIRTIO_VSOCK_SKB_FLAGS_REPLY;
> > +}
> > +
> > +static inline bool virtio_vsock_skb_tap_delivered(struct sk_buff *skb)
> > +{
> > +	return skb->_skb_refdst & VIRTIO_VSOCK_SKB_FLAGS_TAP_DELIVERED;
> > +}
> > +
> > +static inline void virtio_vsock_skb_set_tap_delivered(struct sk_buff *skb)
> > +{
> > +	skb->_skb_refdst |= VIRTIO_VSOCK_SKB_FLAGS_TAP_DELIVERED;
> > +}
> > +
> > +static inline void virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
> > +{
> > +	skb->_skb_refdst &= ~VIRTIO_VSOCK_SKB_FLAGS_TAP_DELIVERED;
> > +}
> > +
> > +static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
> > +{
> > +	u32 len;
> > +
> > +	len = le32_to_cpu(virtio_vsock_hdr(skb)->len);
> > +
> > +	if (len > 0)
> > +		skb_put(skb, len);
> > +}
> > +
> > +static inline void virtio_vsock_kfree_skb(struct sk_buff *skb)
> > +{
> > +	skb->_skb_refdst = 0;
> > +	kfree_skb(skb);
> > +}
> > +
> > +static inline void virtio_vsock_skb_queue_purge(struct sk_buff_head *queue)
> > +{
> > +	struct sk_buff *skb;
> > +
> > +	while ((skb = __skb_dequeue(queue)) != NULL)
> > +		virtio_vsock_kfree_skb(skb);
> > +}
> > +
> > +static inline size_t virtio_vsock_skb_len(struct sk_buff *skb)
> > +{
> > +	return (size_t)(skb_end_pointer(skb) - skb->head);
> > +}
> > +
> > +static inline void virtio_vsock_consume_skb(struct sk_buff *skb)
> > +{
> > +	skb->_skb_refdst = 0;
> > +	consume_skb(skb);
> > +}
> > +
> > #define VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE	(1024 * 4)
> > #define VIRTIO_VSOCK_MAX_BUF_SIZE		0xFFFFFFFFUL
> > #define VIRTIO_VSOCK_MAX_PKT_BUF_SIZE		(1024 * 64)
> > @@ -35,23 +108,10 @@ struct virtio_vsock_sock {
> > 	u32 last_fwd_cnt;
> > 	u32 rx_bytes;
> > 	u32 buf_alloc;
> > -	struct list_head rx_queue;
> > +	struct sk_buff_head rx_queue;
> > 	u32 msg_count;
> > };
> > 
> > -struct virtio_vsock_pkt {
> > -	struct virtio_vsock_hdr	hdr;
> > -	struct list_head list;
> > -	/* socket refcnt not held, only use for cancellation */
> > -	struct vsock_sock *vsk;
> > -	void *buf;
> > -	u32 buf_len;
> > -	u32 len;
> > -	u32 off;
> > -	bool reply;
> > -	bool tap_delivered;
> > -};
> > -
> > struct virtio_vsock_pkt_info {
> > 	u32 remote_cid, remote_port;
> > 	struct vsock_sock *vsk;
> > @@ -68,7 +128,7 @@ struct virtio_transport {
> > 	struct vsock_transport transport;
> > 
> > 	/* Takes ownership of the packet */
> > -	int (*send_pkt)(struct virtio_vsock_pkt *pkt);
> > +	int (*send_pkt)(struct sk_buff *skb);
> > };
> > 
> > ssize_t
> > @@ -149,11 +209,10 @@ virtio_transport_dgram_enqueue(struct vsock_sock *vsk,
> > void virtio_transport_destruct(struct vsock_sock *vsk);
> > 
> > void virtio_transport_recv_pkt(struct virtio_transport *t,
> > -			       struct virtio_vsock_pkt *pkt);
> > -void virtio_transport_free_pkt(struct virtio_vsock_pkt *pkt);
> > -void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt);
> > +			       struct sk_buff *skb);
> > +void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct sk_buff *skb);
> > u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 wanted);
> > void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit);
> > -void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt);
> > -
> > +void virtio_transport_deliver_tap_pkt(struct sk_buff *skb);
> > +int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *queue);
> > #endif /* _LINUX_VIRTIO_VSOCK_H */
> > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> > index ad64f403536a..172dbc52a370 100644
> > --- a/net/vmw_vsock/virtio_transport.c
> > +++ b/net/vmw_vsock/virtio_transport.c
> > @@ -42,8 +42,7 @@ struct virtio_vsock {
> > 	bool tx_run;
> > 
> > 	struct work_struct send_pkt_work;
> > -	spinlock_t send_pkt_list_lock;
> > -	struct list_head send_pkt_list;
> > +	struct sk_buff_head send_pkt_queue;
> > 
> > 	atomic_t queued_replies;
> > 
> > @@ -101,41 +100,36 @@ virtio_transport_send_pkt_work(struct work_struct *work)
> > 	vq = vsock->vqs[VSOCK_VQ_TX];
> > 
> > 	for (;;) {
> > -		struct virtio_vsock_pkt *pkt;
> > 		struct scatterlist hdr, buf, *sgs[2];
> > 		int ret, in_sg = 0, out_sg = 0;
> > +		struct sk_buff *skb;
> > 		bool reply;
> > 
> > -		spin_lock_bh(&vsock->send_pkt_list_lock);
> > -		if (list_empty(&vsock->send_pkt_list)) {
> > -			spin_unlock_bh(&vsock->send_pkt_list_lock);
> > -			break;
> > -		}
> > -
> > -		pkt = list_first_entry(&vsock->send_pkt_list,
> > -				       struct virtio_vsock_pkt, list);
> > -		list_del_init(&pkt->list);
> > -		spin_unlock_bh(&vsock->send_pkt_list_lock);
> > +		spin_lock(&vsock->send_pkt_queue.lock);
> > +		skb = __skb_dequeue(&vsock->send_pkt_queue);
> > +		spin_unlock(&vsock->send_pkt_queue.lock);
> > 
> > -		virtio_transport_deliver_tap_pkt(pkt);
> > +		if (!skb)
> > +			break;
> > 
> > -		reply = pkt->reply;
> > +		virtio_transport_deliver_tap_pkt(skb);
> > +		reply = virtio_vsock_skb_reply(skb);
> > 
> > -		sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
> > +		sg_init_one(&hdr, virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb)));
> > 		sgs[out_sg++] = &hdr;
> > -		if (pkt->buf) {
> > -			sg_init_one(&buf, pkt->buf, pkt->len);
> > +		if (skb->len > 0) {
> > +			sg_init_one(&buf, skb->data, skb->len);
> > 			sgs[out_sg++] = &buf;
> > 		}
> > 
> > -		ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, pkt, GFP_KERNEL);
> > +		ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
> > 		/* Usually this means that there is no more space available in
> > 		 * the vq
> > 		 */
> > 		if (ret < 0) {
> > -			spin_lock_bh(&vsock->send_pkt_list_lock);
> > -			list_add(&pkt->list, &vsock->send_pkt_list);
> > -			spin_unlock_bh(&vsock->send_pkt_list_lock);
> > +			spin_lock(&vsock->send_pkt_queue.lock);
> > +			__skb_queue_head(&vsock->send_pkt_queue, skb);
> > +			spin_unlock(&vsock->send_pkt_queue.lock);
> > 			break;
> > 		}
> > 
> > @@ -164,32 +158,34 @@ virtio_transport_send_pkt_work(struct work_struct *work)
> > }
> > 
> > static int
> > -virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt)
> > +virtio_transport_send_pkt(struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr;
> > 	struct virtio_vsock *vsock;
> > -	int len = pkt->len;
> > +	int len = skb->len;
> > +
> > +	hdr = virtio_vsock_hdr(skb);
> > 
> > 	rcu_read_lock();
> > 	vsock = rcu_dereference(the_virtio_vsock);
> > 	if (!vsock) {
> > -		virtio_transport_free_pkt(pkt);
> > +		virtio_vsock_kfree_skb(skb);
> > 		len = -ENODEV;
> > 		goto out_rcu;
> > 	}
> > 
> > -	if (le64_to_cpu(pkt->hdr.dst_cid) == vsock->guest_cid) {
> > -		virtio_transport_free_pkt(pkt);
> > +	if (le64_to_cpu(hdr->dst_cid) == vsock->guest_cid) {
> > +		virtio_vsock_kfree_skb(skb);
> > 		len = -ENODEV;
> > 		goto out_rcu;
> > 	}
> > 
> > -	if (pkt->reply)
> > +	if (virtio_vsock_skb_reply(skb))
> > 		atomic_inc(&vsock->queued_replies);
> > 
> > -	spin_lock_bh(&vsock->send_pkt_list_lock);
> > -	list_add_tail(&pkt->list, &vsock->send_pkt_list);
> > -	spin_unlock_bh(&vsock->send_pkt_list_lock);
> > -
> > +	spin_lock(&vsock->send_pkt_queue.lock);
> > +	__skb_queue_tail(&vsock->send_pkt_queue, skb);
> > +	spin_unlock(&vsock->send_pkt_queue.lock);
> > 	queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
> > 
> > out_rcu:
> > @@ -201,9 +197,7 @@ static int
> > virtio_transport_cancel_pkt(struct vsock_sock *vsk)
> > {
> > 	struct virtio_vsock *vsock;
> > -	struct virtio_vsock_pkt *pkt, *n;
> > 	int cnt = 0, ret;
> > -	LIST_HEAD(freeme);
> > 
> > 	rcu_read_lock();
> > 	vsock = rcu_dereference(the_virtio_vsock);
> > @@ -212,20 +206,7 @@ virtio_transport_cancel_pkt(struct vsock_sock *vsk)
> > 		goto out_rcu;
> > 	}
> > 
> > -	spin_lock_bh(&vsock->send_pkt_list_lock);
> > -	list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) {
> > -		if (pkt->vsk != vsk)
> > -			continue;
> > -		list_move(&pkt->list, &freeme);
> > -	}
> > -	spin_unlock_bh(&vsock->send_pkt_list_lock);
> > -
> > -	list_for_each_entry_safe(pkt, n, &freeme, list) {
> > -		if (pkt->reply)
> > -			cnt++;
> > -		list_del(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > -	}
> > +	cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
> > 
> > 	if (cnt) {
> > 		struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
> > @@ -246,38 +227,29 @@ virtio_transport_cancel_pkt(struct vsock_sock *vsk)
> > 
> > static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
> > {
> > -	int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
> > -	struct virtio_vsock_pkt *pkt;
> > -	struct scatterlist hdr, buf, *sgs[2];
> > +	int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE +
> 
> Since we are changing the meaning, maybe we can rename this variable in
> total_len or skb_data_len, what do you think?
> 
> > VIRTIO_VSOCK_SKB_HEADROOM;
> > +	struct scatterlist pkt, *p;
> > 	struct virtqueue *vq;
> > +	struct sk_buff *skb;
> > 	int ret;
> > 
> > 	vq = vsock->vqs[VSOCK_VQ_RX];
> > 
> > 	do {
> > -		pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
> > -		if (!pkt)
> > +		skb = alloc_skb(buf_len, GFP_KERNEL);
> > +		if (!skb)
> > 			break;
> > 
> 
> Why don't we call skb_reserve() here, but do it later in
> virtio_transport_rx_work()?
> 
> If we add virtio_vsock_alloc_skb(), I think we can reuse it also here.
> 

Good point, I was trying to keep the calls that adjust the skb data/tail
pointers in one place, but I agree that skb_reserve() really belongs in
a helper with the allocation.

> 
> > -		pkt->buf = kmalloc(buf_len, GFP_KERNEL);
> > -		if (!pkt->buf) {
> > -			virtio_transport_free_pkt(pkt);
> > -			break;
> > -		}
> > -
> > -		pkt->buf_len = buf_len;
> > -		pkt->len = buf_len;
> > -
> > -		sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
> > -		sgs[0] = &hdr;
> > +		memset(skb->head, 0, VIRTIO_VSOCK_SKB_HEADROOM);
> > 
> > -		sg_init_one(&buf, pkt->buf, buf_len);
> > -		sgs[1] = &buf;
> > -		ret = virtqueue_add_sgs(vq, sgs, 0, 2, pkt, GFP_KERNEL);
> > -		if (ret) {
> > -			virtio_transport_free_pkt(pkt);
> > +		sg_init_one(&pkt, virtio_vsock_hdr(skb), buf_len);
> > +		p = &pkt;
> > +		ret = virtqueue_add_sgs(vq, &p, 0, 1, skb, GFP_KERNEL);
> > +		if (ret < 0) {
> > +			virtio_vsock_kfree_skb(skb);
> > 			break;
> > 		}
> > +
> > 		vsock->rx_buf_nr++;
> > 	} while (vq->num_free);
> > 	if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
> > @@ -299,12 +271,12 @@ static void virtio_transport_tx_work(struct work_struct *work)
> > 		goto out;
> > 
> > 	do {
> > -		struct virtio_vsock_pkt *pkt;
> > +		struct sk_buff *skb;
> > 		unsigned int len;
> > 
> > 		virtqueue_disable_cb(vq);
> > -		while ((pkt = virtqueue_get_buf(vq, &len)) != NULL) {
> > -			virtio_transport_free_pkt(pkt);
> > +		while ((skb = virtqueue_get_buf(vq, &len)) != NULL) {
> > +			virtio_vsock_consume_skb(skb);
> > 			added = true;
> > 		}
> > 	} while (!virtqueue_enable_cb(vq));
> > @@ -529,7 +501,7 @@ static void virtio_transport_rx_work(struct work_struct *work)
> > 	do {
> > 		virtqueue_disable_cb(vq);
> > 		for (;;) {
> > -			struct virtio_vsock_pkt *pkt;
> > +			struct sk_buff *skb;
> > 			unsigned int len;
> > 
> > 			if (!virtio_transport_more_replies(vsock)) {
> > @@ -540,23 +512,23 @@ static void virtio_transport_rx_work(struct work_struct *work)
> > 				goto out;
> > 			}
> > 
> > -			pkt = virtqueue_get_buf(vq, &len);
> > -			if (!pkt) {
> > +			skb = virtqueue_get_buf(vq, &len);
> > +			if (!skb)
> > 				break;
> > -			}
> > 
> > 			vsock->rx_buf_nr--;
> > 
> > 			/* Drop short/long packets */
> > -			if (unlikely(len < sizeof(pkt->hdr) ||
> > -				     len > sizeof(pkt->hdr) + pkt->len)) {
> > -				virtio_transport_free_pkt(pkt);
> > +			if (unlikely(len < sizeof(struct virtio_vsock_hdr) ||
> > +				     len > virtio_vsock_skb_len(skb))) {
> > +				virtio_vsock_kfree_skb(skb);
> > 				continue;
> > 			}
> > 
> > -			pkt->len = len - sizeof(pkt->hdr);
> > -			virtio_transport_deliver_tap_pkt(pkt);
> > -			virtio_transport_recv_pkt(&virtio_transport, pkt);
> > +			skb_reserve(skb, VIRTIO_VSOCK_SKB_HEADROOM);
> > +			virtio_vsock_skb_rx_put(skb);
> > +			virtio_transport_deliver_tap_pkt(skb);
> > +			virtio_transport_recv_pkt(&virtio_transport, skb);
> > 		}
> > 	} while (!virtqueue_enable_cb(vq));
> > 
> > @@ -610,7 +582,7 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
> > static void virtio_vsock_vqs_del(struct virtio_vsock *vsock)
> > {
> > 	struct virtio_device *vdev = vsock->vdev;
> > -	struct virtio_vsock_pkt *pkt;
> > +	struct sk_buff *skb;
> > 
> > 	/* Reset all connected sockets when the VQs disappear */
> > 	vsock_for_each_connected_socket(&virtio_transport.transport,
> > @@ -637,23 +609,18 @@ static void virtio_vsock_vqs_del(struct virtio_vsock *vsock)
> > 	virtio_reset_device(vdev);
> > 
> > 	mutex_lock(&vsock->rx_lock);
> > -	while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
> > -		virtio_transport_free_pkt(pkt);
> > +	while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
> > +		virtio_vsock_kfree_skb(skb);
> > 	mutex_unlock(&vsock->rx_lock);
> > 
> > 	mutex_lock(&vsock->tx_lock);
> > -	while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
> > -		virtio_transport_free_pkt(pkt);
> > +	while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
> > +		virtio_vsock_kfree_skb(skb);
> > 	mutex_unlock(&vsock->tx_lock);
> > 
> > -	spin_lock_bh(&vsock->send_pkt_list_lock);
> > -	while (!list_empty(&vsock->send_pkt_list)) {
> > -		pkt = list_first_entry(&vsock->send_pkt_list,
> > -				       struct virtio_vsock_pkt, list);
> > -		list_del(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > -	}
> > -	spin_unlock_bh(&vsock->send_pkt_list_lock);
> > +	spin_lock(&vsock->send_pkt_queue.lock);
> > +	virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
> > +	spin_unlock(&vsock->send_pkt_queue.lock);
> > 
> > 	/* Delete virtqueues and flush outstanding callbacks if any */
> > 	vdev->config->del_vqs(vdev);
> > @@ -690,8 +657,7 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
> > 	mutex_init(&vsock->tx_lock);
> > 	mutex_init(&vsock->rx_lock);
> > 	mutex_init(&vsock->event_lock);
> > -	spin_lock_init(&vsock->send_pkt_list_lock);
> > -	INIT_LIST_HEAD(&vsock->send_pkt_list);
> > +	skb_queue_head_init(&vsock->send_pkt_queue);
> > 	INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
> > 	INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
> > 	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
> > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> > index a9980e9b9304..b40a17cbbccf 100644
> > --- a/net/vmw_vsock/virtio_transport_common.c
> > +++ b/net/vmw_vsock/virtio_transport_common.c
> > @@ -37,53 +37,58 @@ virtio_transport_get_ops(struct vsock_sock *vsk)
> > 	return container_of(t, struct virtio_transport, transport);
> > }
> > 
> > -static struct virtio_vsock_pkt *
> > -virtio_transport_alloc_pkt(struct virtio_vsock_pkt_info *info,
> > +/* Returns a new packet on success, otherwise returns NULL.
> > + *
> > + * If NULL is returned, errp is set to a negative errno.
> > + */
> > +static struct sk_buff *
> > +virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
> > 			   size_t len,
> > 			   u32 src_cid,
> > 			   u32 src_port,
> > 			   u32 dst_cid,
> > 			   u32 dst_port)
> > {
> > -	struct virtio_vsock_pkt *pkt;
> > +	const size_t skb_len = VIRTIO_VSOCK_SKB_HEADROOM + len;
> > +	struct virtio_vsock_hdr *hdr;
> > +	struct sk_buff *skb;
> > +	void *payload;
> > 	int err;
> > 
> > -	pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
> > -	if (!pkt)
> > +	skb = alloc_skb(skb_len, GFP_KERNEL);
> > +	if (!skb)
> > 		return NULL;
> > 
> > -	pkt->hdr.type		= cpu_to_le16(info->type);
> > -	pkt->hdr.op		= cpu_to_le16(info->op);
> > -	pkt->hdr.src_cid	= cpu_to_le64(src_cid);
> > -	pkt->hdr.dst_cid	= cpu_to_le64(dst_cid);
> > -	pkt->hdr.src_port	= cpu_to_le32(src_port);
> > -	pkt->hdr.dst_port	= cpu_to_le32(dst_port);
> > -	pkt->hdr.flags		= cpu_to_le32(info->flags);
> > -	pkt->len		= len;
> > -	pkt->hdr.len		= cpu_to_le32(len);
> > -	pkt->reply		= info->reply;
> > -	pkt->vsk		= info->vsk;
> > +	skb_reserve(skb, VIRTIO_VSOCK_SKB_HEADROOM);
> > +	payload = skb_put(skb, len);
> > 
> > -	if (info->msg && len > 0) {
> > -		pkt->buf = kmalloc(len, GFP_KERNEL);
> > -		if (!pkt->buf)
> > -			goto out_pkt;
> > -
> > -		pkt->buf_len = len;
> > +	hdr = virtio_vsock_hdr(skb);
> > +	hdr->type	= cpu_to_le16(info->type);
> > +	hdr->op		= cpu_to_le16(info->op);
> > +	hdr->src_cid	= cpu_to_le64(src_cid);
> > +	hdr->dst_cid	= cpu_to_le64(dst_cid);
> > +	hdr->src_port	= cpu_to_le32(src_port);
> > +	hdr->dst_port	= cpu_to_le32(dst_port);
> > +	hdr->flags	= cpu_to_le32(info->flags);
> > +	hdr->len	= cpu_to_le32(len);
> > 
> > -		err = memcpy_from_msg(pkt->buf, info->msg, len);
> > +	if (info->msg && len > 0) {
> > +		err = memcpy_from_msg(payload, info->msg, len);
> > 		if (err)
> > 			goto out;
> > 
> > 		if (msg_data_left(info->msg) == 0 &&
> > 		    info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) {
> > -			pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> > +			hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
> > 
> > 			if (info->msg->msg_flags & MSG_EOR)
> > -				pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> > +				hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
> > 		}
> > 	}
> > 
> > +	if (info->reply)
> > +		virtio_vsock_skb_set_reply(skb);
> > +
> > 	trace_virtio_transport_alloc_pkt(src_cid, src_port,
> > 					 dst_cid, dst_port,
> > 					 len,
> > @@ -91,85 +96,26 @@ virtio_transport_alloc_pkt(struct virtio_vsock_pkt_info *info,
> > 					 info->op,
> > 					 info->flags);
> > 
> > -	return pkt;
> > +	return skb;
> > 
> > out:
> > -	kfree(pkt->buf);
> > -out_pkt:
> > -	kfree(pkt);
> > +	virtio_vsock_kfree_skb(skb);
> > 	return NULL;
> > }
> > 
> > /* Packet capture */
> > static struct sk_buff *virtio_transport_build_skb(void *opaque)
> > {
> > -	struct virtio_vsock_pkt *pkt = opaque;
> > -	struct af_vsockmon_hdr *hdr;
> > -	struct sk_buff *skb;
> > -	size_t payload_len;
> > -	void *payload_buf;
> > -
> > -	/* A packet could be split to fit the RX buffer, so we can retrieve
> > -	 * the payload length from the header and the buffer pointer taking
> > -	 * care of the offset in the original packet.
> > -	 */
> > -	payload_len = le32_to_cpu(pkt->hdr.len);
> > -	payload_buf = pkt->buf + pkt->off;
> > -
> > -	skb = alloc_skb(sizeof(*hdr) + sizeof(pkt->hdr) + payload_len,
> > -			GFP_ATOMIC);
> > -	if (!skb)
> > -		return NULL;
> > -
> > -	hdr = skb_put(skb, sizeof(*hdr));
> > -
> > -	/* pkt->hdr is little-endian so no need to byteswap here */
> > -	hdr->src_cid = pkt->hdr.src_cid;
> > -	hdr->src_port = pkt->hdr.src_port;
> > -	hdr->dst_cid = pkt->hdr.dst_cid;
> > -	hdr->dst_port = pkt->hdr.dst_port;
> > -
> > -	hdr->transport = cpu_to_le16(AF_VSOCK_TRANSPORT_VIRTIO);
> > -	hdr->len = cpu_to_le16(sizeof(pkt->hdr));
> > -	memset(hdr->reserved, 0, sizeof(hdr->reserved));
> > -
> > -	switch (le16_to_cpu(pkt->hdr.op)) {
> > -	case VIRTIO_VSOCK_OP_REQUEST:
> > -	case VIRTIO_VSOCK_OP_RESPONSE:
> > -		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONNECT);
> > -		break;
> > -	case VIRTIO_VSOCK_OP_RST:
> > -	case VIRTIO_VSOCK_OP_SHUTDOWN:
> > -		hdr->op = cpu_to_le16(AF_VSOCK_OP_DISCONNECT);
> > -		break;
> > -	case VIRTIO_VSOCK_OP_RW:
> > -		hdr->op = cpu_to_le16(AF_VSOCK_OP_PAYLOAD);
> > -		break;
> > -	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
> > -	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
> > -		hdr->op = cpu_to_le16(AF_VSOCK_OP_CONTROL);
> > -		break;
> > -	default:
> > -		hdr->op = cpu_to_le16(AF_VSOCK_OP_UNKNOWN);
> > -		break;
> > -	}
> > -
> > -	skb_put_data(skb, &pkt->hdr, sizeof(pkt->hdr));
> > -
> > -	if (payload_len) {
> > -		skb_put_data(skb, payload_buf, payload_len);
> > -	}
> > -
> > -	return skb;
> > +	return skb_copy(opaque, GFP_ATOMIC);
> 
> I don't think we can make a simple copy, af_vsockmon_hdr is different from
> virtio_vsock_hdr.
> 
> Have you tried to see if wireshark, tcpdump works?
> 

I'll give it a test. Seems like I overlooked that detail.

> > }
> > 
> > -void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
> > +void virtio_transport_deliver_tap_pkt(struct sk_buff *skb)
> > {
> > -	if (pkt->tap_delivered)
> > +	if (virtio_vsock_skb_tap_delivered(skb))
> > 		return;
> > 
> > -	vsock_deliver_tap(virtio_transport_build_skb, pkt);
> > -	pkt->tap_delivered = true;
> > +	vsock_deliver_tap(virtio_transport_build_skb, skb);
> > +	virtio_vsock_skb_set_tap_delivered(skb);
> > }
> > EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);
> > 
> > @@ -192,8 +138,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
> > 	u32 src_cid, src_port, dst_cid, dst_port;
> > 	const struct virtio_transport *t_ops;
> > 	struct virtio_vsock_sock *vvs;
> > -	struct virtio_vsock_pkt *pkt;
> > 	u32 pkt_len = info->pkt_len;
> > +	struct sk_buff *skb;
> > 
> > 	info->type = virtio_transport_get_type(sk_vsock(vsk));
> > 
> > @@ -224,42 +170,47 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
> > 	if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
> > 		return pkt_len;
> > 
> > -	pkt = virtio_transport_alloc_pkt(info, pkt_len,
> > +	skb = virtio_transport_alloc_skb(info, pkt_len,
> > 					 src_cid, src_port,
> > 					 dst_cid, dst_port);
> > -	if (!pkt) {
> > +	if (!skb) {
> > 		virtio_transport_put_credit(vvs, pkt_len);
> > 		return -ENOMEM;
> > 	}
> > 
> > -	virtio_transport_inc_tx_pkt(vvs, pkt);
> > +	virtio_transport_inc_tx_pkt(vvs, skb);
> > 
> > -	return t_ops->send_pkt(pkt);
> > +	return t_ops->send_pkt(skb);
> > }
> > 
> > static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
> > -					struct virtio_vsock_pkt *pkt)
> > +					struct sk_buff *skb)
> > {
> > -	if (vvs->rx_bytes + pkt->len > vvs->buf_alloc)
> > +	if (vvs->rx_bytes + skb->len > vvs->buf_alloc)
> > 		return false;
> > 
> > -	vvs->rx_bytes += pkt->len;
> > +	vvs->rx_bytes += skb->len;
> > 	return true;
> > }
> > 
> > static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
> > -					struct virtio_vsock_pkt *pkt)
> > +					struct sk_buff *skb)
> > {
> > -	vvs->rx_bytes -= pkt->len;
> > -	vvs->fwd_cnt += pkt->len;
> > +	int len;
> > +
> > +	len = skb_headroom(skb) - sizeof(struct virtio_vsock_hdr) - skb->len;
> > +	vvs->rx_bytes -= len;
> > +	vvs->fwd_cnt += len;
> > }
> > 
> > -void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt)
> > +void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > +
> > 	spin_lock_bh(&vvs->rx_lock);
> > 	vvs->last_fwd_cnt = vvs->fwd_cnt;
> > -	pkt->hdr.fwd_cnt = cpu_to_le32(vvs->fwd_cnt);
> > -	pkt->hdr.buf_alloc = cpu_to_le32(vvs->buf_alloc);
> > +	hdr->fwd_cnt = cpu_to_le32(vvs->fwd_cnt);
> > +	hdr->buf_alloc = cpu_to_le32(vvs->buf_alloc);
> > 	spin_unlock_bh(&vvs->rx_lock);
> > }
> > EXPORT_SYMBOL_GPL(virtio_transport_inc_tx_pkt);
> > @@ -303,29 +254,29 @@ virtio_transport_stream_do_peek(struct vsock_sock *vsk,
> > 				size_t len)
> > {
> > 	struct virtio_vsock_sock *vvs = vsk->trans;
> > -	struct virtio_vsock_pkt *pkt;
> > 	size_t bytes, total = 0, off;
> > +	struct sk_buff *skb, *tmp;
> > 	int err = -EFAULT;
> > 
> > 	spin_lock_bh(&vvs->rx_lock);
> > 
> > -	list_for_each_entry(pkt, &vvs->rx_queue, list) {
> > -		off = pkt->off;
> > +	skb_queue_walk_safe(&vvs->rx_queue, skb,  tmp) {
> > +		off = 0;
> > 
> > 		if (total == len)
> > 			break;
> > 
> > -		while (total < len && off < pkt->len) {
> > +		while (total < len && off < skb->len) {
> > 			bytes = len - total;
> > -			if (bytes > pkt->len - off)
> > -				bytes = pkt->len - off;
> > +			if (bytes > skb->len - off)
> > +				bytes = skb->len - off;
> > 
> > 			/* sk_lock is held by caller so no one else can dequeue.
> > 			 * Unlock rx_lock since memcpy_to_msg() may sleep.
> > 			 */
> > 			spin_unlock_bh(&vvs->rx_lock);
> > 
> > -			err = memcpy_to_msg(msg, pkt->buf + off, bytes);
> > +			err = memcpy_to_msg(msg, skb->data + off, bytes);
> > 			if (err)
> > 				goto out;
> > 
> > @@ -352,37 +303,38 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
> > 				   size_t len)
> > {
> > 	struct virtio_vsock_sock *vvs = vsk->trans;
> > -	struct virtio_vsock_pkt *pkt;
> > 	size_t bytes, total = 0;
> > -	u32 free_space;
> > +	struct sk_buff *skb;
> > 	int err = -EFAULT;
> > +	u32 free_space;
> > 
> > 	spin_lock_bh(&vvs->rx_lock);
> > -	while (total < len && !list_empty(&vvs->rx_queue)) {
> > -		pkt = list_first_entry(&vvs->rx_queue,
> > -				       struct virtio_vsock_pkt, list);
> > +	while (total < len && !skb_queue_empty_lockless(&vvs->rx_queue)) {
> > +		skb = __skb_dequeue(&vvs->rx_queue);
> > 
> > 		bytes = len - total;
> > -		if (bytes > pkt->len - pkt->off)
> > -			bytes = pkt->len - pkt->off;
> > +		if (bytes > skb->len)
> > +			bytes = skb->len;
> > 
> > 		/* sk_lock is held by caller so no one else can dequeue.
> > 		 * Unlock rx_lock since memcpy_to_msg() may sleep.
> > 		 */
> > 		spin_unlock_bh(&vvs->rx_lock);
> > 
> > -		err = memcpy_to_msg(msg, pkt->buf + pkt->off, bytes);
> > +		err = memcpy_to_msg(msg, skb->data, bytes);
> > 		if (err)
> > 			goto out;
> > 
> > 		spin_lock_bh(&vvs->rx_lock);
> > 
> > 		total += bytes;
> > -		pkt->off += bytes;
> > -		if (pkt->off == pkt->len) {
> > -			virtio_transport_dec_rx_pkt(vvs, pkt);
> > -			list_del(&pkt->list);
> > -			virtio_transport_free_pkt(pkt);
> > +		skb_pull(skb, bytes);
> > +
> > +		if (skb->len == 0) {
> > +			virtio_transport_dec_rx_pkt(vvs, skb);
> > +			virtio_vsock_consume_skb(skb);
> > +		} else {
> > +			__skb_queue_head(&vvs->rx_queue, skb);
> > 		}
> > 	}
> > 
> > @@ -414,10 +366,10 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
> > 						 int flags)
> > {
> > 	struct virtio_vsock_sock *vvs = vsk->trans;
> > -	struct virtio_vsock_pkt *pkt;
> > 	int dequeued_len = 0;
> > 	size_t user_buf_len = msg_data_left(msg);
> > 	bool msg_ready = false;
> > +	struct sk_buff *skb;
> > 
> > 	spin_lock_bh(&vvs->rx_lock);
> > 
> > @@ -427,13 +379,18 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
> > 	}
> > 
> > 	while (!msg_ready) {
> > -		pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list);
> > +		struct virtio_vsock_hdr *hdr;
> > +
> > +		skb = __skb_dequeue(&vvs->rx_queue);
> > +		if (!skb)
> > +			break;
> > +		hdr = virtio_vsock_hdr(skb);
> > 
> > 		if (dequeued_len >= 0) {
> > 			size_t pkt_len;
> > 			size_t bytes_to_copy;
> > 
> > -			pkt_len = (size_t)le32_to_cpu(pkt->hdr.len);
> > +			pkt_len = (size_t)le32_to_cpu(hdr->len);
> > 			bytes_to_copy = min(user_buf_len, pkt_len);
> > 
> > 			if (bytes_to_copy) {
> > @@ -444,7 +401,7 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
> > 				 */
> > 				spin_unlock_bh(&vvs->rx_lock);
> > 
> > -				err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy);
> > +				err = memcpy_to_msg(msg, skb->data, bytes_to_copy);
> > 				if (err) {
> > 					/* Copy of message failed. Rest of
> > 					 * fragments will be freed without copy.
> > @@ -452,6 +409,7 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
> > 					dequeued_len = err;
> > 				} else {
> > 					user_buf_len -= bytes_to_copy;
> > +					skb_pull(skb, bytes_to_copy);
> > 				}
> > 
> > 				spin_lock_bh(&vvs->rx_lock);
> > @@ -461,17 +419,16 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
> > 				dequeued_len += pkt_len;
> > 		}
> > 
> > -		if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
> > +		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
> > 			msg_ready = true;
> > 			vvs->msg_count--;
> > 
> > -			if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR)
> > +			if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR)
> > 				msg->msg_flags |= MSG_EOR;
> > 		}
> > 
> > -		virtio_transport_dec_rx_pkt(vvs, pkt);
> > -		list_del(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > +		virtio_transport_dec_rx_pkt(vvs, skb);
> > +		virtio_vsock_kfree_skb(skb);
> > 	}
> > 
> > 	spin_unlock_bh(&vvs->rx_lock);
> > @@ -609,7 +566,7 @@ int virtio_transport_do_socket_init(struct vsock_sock *vsk,
> > 
> > 	spin_lock_init(&vvs->rx_lock);
> > 	spin_lock_init(&vvs->tx_lock);
> > -	INIT_LIST_HEAD(&vvs->rx_queue);
> > +	skb_queue_head_init(&vvs->rx_queue);
> > 
> > 	return 0;
> > }
> > @@ -806,16 +763,16 @@ void virtio_transport_destruct(struct vsock_sock *vsk)
> > EXPORT_SYMBOL_GPL(virtio_transport_destruct);
> > 
> > static int virtio_transport_reset(struct vsock_sock *vsk,
> > -				  struct virtio_vsock_pkt *pkt)
> > +				  struct sk_buff *skb)
> > {
> > 	struct virtio_vsock_pkt_info info = {
> > 		.op = VIRTIO_VSOCK_OP_RST,
> > -		.reply = !!pkt,
> > +		.reply = !!skb,
> > 		.vsk = vsk,
> > 	};
> > 
> > 	/* Send RST only if the original pkt is not a RST pkt */
> > -	if (pkt && le16_to_cpu(pkt->hdr.op) == VIRTIO_VSOCK_OP_RST)
> > +	if (skb && le16_to_cpu(virtio_vsock_hdr(skb)->op) == VIRTIO_VSOCK_OP_RST)
> > 		return 0;
> > 
> > 	return virtio_transport_send_pkt_info(vsk, &info);
> > @@ -825,29 +782,30 @@ static int virtio_transport_reset(struct vsock_sock *vsk,
> >  * attempt was made to connect to a socket that does not exist.
> >  */
> > static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
> > -					  struct virtio_vsock_pkt *pkt)
> > +					  struct sk_buff *skb)
> > {
> > -	struct virtio_vsock_pkt *reply;
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct virtio_vsock_pkt_info info = {
> > 		.op = VIRTIO_VSOCK_OP_RST,
> > -		.type = le16_to_cpu(pkt->hdr.type),
> > +		.type = le16_to_cpu(hdr->type),
> > 		.reply = true,
> > 	};
> > +	struct sk_buff *reply;
> > 
> > 	/* Send RST only if the original pkt is not a RST pkt */
> > -	if (le16_to_cpu(pkt->hdr.op) == VIRTIO_VSOCK_OP_RST)
> > +	if (le16_to_cpu(hdr->op) == VIRTIO_VSOCK_OP_RST)
> > 		return 0;
> > 
> > -	reply = virtio_transport_alloc_pkt(&info, 0,
> > -					   le64_to_cpu(pkt->hdr.dst_cid),
> > -					   le32_to_cpu(pkt->hdr.dst_port),
> > -					   le64_to_cpu(pkt->hdr.src_cid),
> > -					   le32_to_cpu(pkt->hdr.src_port));
> > +	reply = virtio_transport_alloc_skb(&info, 0,
> > +					   le64_to_cpu(hdr->dst_cid),
> > +					   le32_to_cpu(hdr->dst_port),
> > +					   le64_to_cpu(hdr->src_cid),
> > +					   le32_to_cpu(hdr->src_port));
> > 	if (!reply)
> > 		return -ENOMEM;
> > 
> > 	if (!t) {
> > -		virtio_transport_free_pkt(reply);
> > +		virtio_vsock_kfree_skb(reply);
> > 		return -ENOTCONN;
> > 	}
> > 
> > @@ -858,16 +816,11 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
> > static void virtio_transport_remove_sock(struct vsock_sock *vsk)
> > {
> > 	struct virtio_vsock_sock *vvs = vsk->trans;
> > -	struct virtio_vsock_pkt *pkt, *tmp;
> > 
> > 	/* We don't need to take rx_lock, as the socket is closing and we are
> > 	 * removing it.
> > 	 */
> > -	list_for_each_entry_safe(pkt, tmp, &vvs->rx_queue, list) {
> > -		list_del(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > -	}
> > -
> > +	virtio_vsock_skb_queue_purge(&vvs->rx_queue);
> > 	vsock_remove_sock(vsk);
> > }
> > 
> > @@ -981,13 +934,14 @@ EXPORT_SYMBOL_GPL(virtio_transport_release);
> > 
> > static int
> > virtio_transport_recv_connecting(struct sock *sk,
> > -				 struct virtio_vsock_pkt *pkt)
> > +				 struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct vsock_sock *vsk = vsock_sk(sk);
> > -	int err;
> > 	int skerr;
> > +	int err;
> > 
> > -	switch (le16_to_cpu(pkt->hdr.op)) {
> > +	switch (le16_to_cpu(hdr->op)) {
> > 	case VIRTIO_VSOCK_OP_RESPONSE:
> > 		sk->sk_state = TCP_ESTABLISHED;
> > 		sk->sk_socket->state = SS_CONNECTED;
> > @@ -1008,7 +962,7 @@ virtio_transport_recv_connecting(struct sock *sk,
> > 	return 0;
> > 
> > destroy:
> > -	virtio_transport_reset(vsk, pkt);
> > +	virtio_transport_reset(vsk, skb);
> > 	sk->sk_state = TCP_CLOSE;
> > 	sk->sk_err = skerr;
> > 	sk_error_report(sk);
> > @@ -1017,34 +971,37 @@ virtio_transport_recv_connecting(struct sock *sk,
> > 
> > static void
> > virtio_transport_recv_enqueue(struct vsock_sock *vsk,
> > -			      struct virtio_vsock_pkt *pkt)
> > +			      struct sk_buff *skb)
> > {
> > 	struct virtio_vsock_sock *vvs = vsk->trans;
> > 	bool can_enqueue, free_pkt = false;
> > +	struct virtio_vsock_hdr *hdr;
> > +	u32 len;
> > 
> > -	pkt->len = le32_to_cpu(pkt->hdr.len);
> > -	pkt->off = 0;
> > +	hdr = virtio_vsock_hdr(skb);
> > +	len = le32_to_cpu(hdr->len);
> > 
> > 	spin_lock_bh(&vvs->rx_lock);
> > 
> > -	can_enqueue = virtio_transport_inc_rx_pkt(vvs, pkt);
> > +	can_enqueue = virtio_transport_inc_rx_pkt(vvs, skb);
> > 	if (!can_enqueue) {
> > 		free_pkt = true;
> > 		goto out;
> > 	}
> > 
> > -	if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM)
> > +	if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM)
> > 		vvs->msg_count++;
> > 
> > 	/* Try to copy small packets into the buffer of last packet queued,
> > 	 * to avoid wasting memory queueing the entire buffer with a small
> > 	 * payload.
> > 	 */
> > -	if (pkt->len <= GOOD_COPY_LEN && !list_empty(&vvs->rx_queue)) {
> > -		struct virtio_vsock_pkt *last_pkt;
> > +	if (len <= GOOD_COPY_LEN && !skb_queue_empty_lockless(&vvs->rx_queue)) {
> > +		struct virtio_vsock_hdr *last_hdr;
> > +		struct sk_buff *last_skb;
> > 
> > -		last_pkt = list_last_entry(&vvs->rx_queue,
> > -					   struct virtio_vsock_pkt, list);
> > +		last_skb = skb_peek_tail(&vvs->rx_queue);
> > +		last_hdr = virtio_vsock_hdr(last_skb);
> > 
> > 		/* If there is space in the last packet queued, we copy the
> > 		 * new packet in its buffer. We avoid this if the last packet
> > @@ -1052,35 +1009,34 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
> > 		 * delimiter of SEQPACKET message, so 'pkt' is the first packet
> > 		 * of a new message.
> > 		 */
> > -		if ((pkt->len <= last_pkt->buf_len - last_pkt->len) &&
> > -		    !(le32_to_cpu(last_pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM)) {
> > -			memcpy(last_pkt->buf + last_pkt->len, pkt->buf,
> > -			       pkt->len);
> > -			last_pkt->len += pkt->len;
> > +		if (skb->len < skb_tailroom(last_skb) &&
> > +		    !(le32_to_cpu(last_hdr->flags) & VIRTIO_VSOCK_SEQ_EOM)) {
> > +			memcpy(skb_put(last_skb, skb->len), skb->data, skb->len);
> > 			free_pkt = true;
> > -			last_pkt->hdr.flags |= pkt->hdr.flags;
> > +			last_hdr->flags |= hdr->flags;
> > 			goto out;
> > 		}
> > 	}
> > 
> > -	list_add_tail(&pkt->list, &vvs->rx_queue);
> > +	__skb_queue_tail(&vvs->rx_queue, skb);
> > 
> > out:
> > 	spin_unlock_bh(&vvs->rx_lock);
> > 	if (free_pkt)
> > -		virtio_transport_free_pkt(pkt);
> > +		virtio_vsock_kfree_skb(skb);
> > }
> > 
> > static int
> > virtio_transport_recv_connected(struct sock *sk,
> > -				struct virtio_vsock_pkt *pkt)
> > +				struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct vsock_sock *vsk = vsock_sk(sk);
> > 	int err = 0;
> > 
> > -	switch (le16_to_cpu(pkt->hdr.op)) {
> > +	switch (le16_to_cpu(hdr->op)) {
> > 	case VIRTIO_VSOCK_OP_RW:
> > -		virtio_transport_recv_enqueue(vsk, pkt);
> > +		virtio_transport_recv_enqueue(vsk, skb);
> > 		vsock_data_ready(sk);
> > 		return err;
> > 	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
> > @@ -1090,18 +1046,17 @@ virtio_transport_recv_connected(struct sock *sk,
> > 		sk->sk_write_space(sk);
> > 		break;
> > 	case VIRTIO_VSOCK_OP_SHUTDOWN:
> > -		if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SHUTDOWN_RCV)
> > +		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SHUTDOWN_RCV)
> > 			vsk->peer_shutdown |= RCV_SHUTDOWN;
> > -		if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SHUTDOWN_SEND)
> > +		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SHUTDOWN_SEND)
> > 			vsk->peer_shutdown |= SEND_SHUTDOWN;
> > 		if (vsk->peer_shutdown == SHUTDOWN_MASK &&
> > 		    vsock_stream_has_data(vsk) <= 0 &&
> > 		    !sock_flag(sk, SOCK_DONE)) {
> > 			(void)virtio_transport_reset(vsk, NULL);
> > -
> > 			virtio_transport_do_close(vsk, true);
> > 		}
> > -		if (le32_to_cpu(pkt->hdr.flags))
> > +		if (le32_to_cpu(virtio_vsock_hdr(skb)->flags))
> > 			sk->sk_state_change(sk);
> > 		break;
> > 	case VIRTIO_VSOCK_OP_RST:
> > @@ -1112,28 +1067,30 @@ virtio_transport_recv_connected(struct sock *sk,
> > 		break;
> > 	}
> > 
> > -	virtio_transport_free_pkt(pkt);
> > +	virtio_vsock_kfree_skb(skb);
> > 	return err;
> > }
> > 
> > static void
> > virtio_transport_recv_disconnecting(struct sock *sk,
> > -				    struct virtio_vsock_pkt *pkt)
> > +				    struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct vsock_sock *vsk = vsock_sk(sk);
> > 
> > -	if (le16_to_cpu(pkt->hdr.op) == VIRTIO_VSOCK_OP_RST)
> > +	if (le16_to_cpu(hdr->op) == VIRTIO_VSOCK_OP_RST)
> > 		virtio_transport_do_close(vsk, true);
> > }
> > 
> > static int
> > virtio_transport_send_response(struct vsock_sock *vsk,
> > -			       struct virtio_vsock_pkt *pkt)
> > +			       struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct virtio_vsock_pkt_info info = {
> > 		.op = VIRTIO_VSOCK_OP_RESPONSE,
> > -		.remote_cid = le64_to_cpu(pkt->hdr.src_cid),
> > -		.remote_port = le32_to_cpu(pkt->hdr.src_port),
> > +		.remote_cid = le64_to_cpu(hdr->src_cid),
> > +		.remote_port = le32_to_cpu(hdr->src_port),
> > 		.reply = true,
> > 		.vsk = vsk,
> > 	};
> > @@ -1142,8 +1099,9 @@ virtio_transport_send_response(struct vsock_sock *vsk,
> > }
> > 
> > static bool virtio_transport_space_update(struct sock *sk,
> > -					  struct virtio_vsock_pkt *pkt)
> > +					  struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct vsock_sock *vsk = vsock_sk(sk);
> > 	struct virtio_vsock_sock *vvs = vsk->trans;
> > 	bool space_available;
> > @@ -1158,8 +1116,8 @@ static bool virtio_transport_space_update(struct sock *sk,
> > 
> > 	/* buf_alloc and fwd_cnt is always included in the hdr */
> > 	spin_lock_bh(&vvs->tx_lock);
> > -	vvs->peer_buf_alloc = le32_to_cpu(pkt->hdr.buf_alloc);
> > -	vvs->peer_fwd_cnt = le32_to_cpu(pkt->hdr.fwd_cnt);
> > +	vvs->peer_buf_alloc = le32_to_cpu(hdr->buf_alloc);
> > +	vvs->peer_fwd_cnt = le32_to_cpu(hdr->fwd_cnt);
> > 	space_available = virtio_transport_has_space(vsk);
> > 	spin_unlock_bh(&vvs->tx_lock);
> > 	return space_available;
> > @@ -1167,27 +1125,28 @@ static bool virtio_transport_space_update(struct sock *sk,
> > 
> > /* Handle server socket */
> > static int
> > -virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
> > +virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
> > 			     struct virtio_transport *t)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct vsock_sock *vsk = vsock_sk(sk);
> > 	struct vsock_sock *vchild;
> > 	struct sock *child;
> > 	int ret;
> > 
> > -	if (le16_to_cpu(pkt->hdr.op) != VIRTIO_VSOCK_OP_REQUEST) {
> > -		virtio_transport_reset_no_sock(t, pkt);
> > +	if (le16_to_cpu(hdr->op) != VIRTIO_VSOCK_OP_REQUEST) {
> > +		virtio_transport_reset_no_sock(t, skb);
> > 		return -EINVAL;
> > 	}
> > 
> > 	if (sk_acceptq_is_full(sk)) {
> > -		virtio_transport_reset_no_sock(t, pkt);
> > +		virtio_transport_reset_no_sock(t, skb);
> > 		return -ENOMEM;
> > 	}
> > 
> > 	child = vsock_create_connected(sk);
> > 	if (!child) {
> > -		virtio_transport_reset_no_sock(t, pkt);
> > +		virtio_transport_reset_no_sock(t, skb);
> > 		return -ENOMEM;
> > 	}
> > 
> > @@ -1198,10 +1157,10 @@ virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
> > 	child->sk_state = TCP_ESTABLISHED;
> > 
> > 	vchild = vsock_sk(child);
> > -	vsock_addr_init(&vchild->local_addr, le64_to_cpu(pkt->hdr.dst_cid),
> > -			le32_to_cpu(pkt->hdr.dst_port));
> > -	vsock_addr_init(&vchild->remote_addr, le64_to_cpu(pkt->hdr.src_cid),
> > -			le32_to_cpu(pkt->hdr.src_port));
> > +	vsock_addr_init(&vchild->local_addr, le64_to_cpu(hdr->dst_cid),
> > +			le32_to_cpu(hdr->dst_port));
> > +	vsock_addr_init(&vchild->remote_addr, le64_to_cpu(hdr->src_cid),
> > +			le32_to_cpu(hdr->src_port));
> > 
> > 	ret = vsock_assign_transport(vchild, vsk);
> > 	/* Transport assigned (looking at remote_addr) must be the same
> > @@ -1209,17 +1168,17 @@ virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
> > 	 */
> > 	if (ret || vchild->transport != &t->transport) {
> > 		release_sock(child);
> > -		virtio_transport_reset_no_sock(t, pkt);
> > +		virtio_transport_reset_no_sock(t, skb);
> > 		sock_put(child);
> > 		return ret;
> > 	}
> > 
> > -	if (virtio_transport_space_update(child, pkt))
> > +	if (virtio_transport_space_update(child, skb))
> > 		child->sk_write_space(child);
> > 
> > 	vsock_insert_connected(vchild);
> > 	vsock_enqueue_accept(sk, child);
> > -	virtio_transport_send_response(vchild, pkt);
> > +	virtio_transport_send_response(vchild, skb);
> > 
> > 	release_sock(child);
> > 
> > @@ -1237,29 +1196,30 @@ static bool virtio_transport_valid_type(u16 type)
> >  * lock.
> >  */
> > void virtio_transport_recv_pkt(struct virtio_transport *t,
> > -			       struct virtio_vsock_pkt *pkt)
> > +			       struct sk_buff *skb)
> > {
> > +	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
> > 	struct sockaddr_vm src, dst;
> > 	struct vsock_sock *vsk;
> > 	struct sock *sk;
> > 	bool space_available;
> > 
> > -	vsock_addr_init(&src, le64_to_cpu(pkt->hdr.src_cid),
> > -			le32_to_cpu(pkt->hdr.src_port));
> > -	vsock_addr_init(&dst, le64_to_cpu(pkt->hdr.dst_cid),
> > -			le32_to_cpu(pkt->hdr.dst_port));
> > +	vsock_addr_init(&src, le64_to_cpu(hdr->src_cid),
> > +			le32_to_cpu(hdr->src_port));
> > +	vsock_addr_init(&dst, le64_to_cpu(hdr->dst_cid),
> > +			le32_to_cpu(hdr->dst_port));
> > 
> > 	trace_virtio_transport_recv_pkt(src.svm_cid, src.svm_port,
> > 					dst.svm_cid, dst.svm_port,
> > -					le32_to_cpu(pkt->hdr.len),
> > -					le16_to_cpu(pkt->hdr.type),
> > -					le16_to_cpu(pkt->hdr.op),
> > -					le32_to_cpu(pkt->hdr.flags),
> > -					le32_to_cpu(pkt->hdr.buf_alloc),
> > -					le32_to_cpu(pkt->hdr.fwd_cnt));
> > -
> > -	if (!virtio_transport_valid_type(le16_to_cpu(pkt->hdr.type))) {
> > -		(void)virtio_transport_reset_no_sock(t, pkt);
> > +					le32_to_cpu(hdr->len),
> > +					le16_to_cpu(hdr->type),
> > +					le16_to_cpu(hdr->op),
> > +					le32_to_cpu(hdr->flags),
> > +					le32_to_cpu(hdr->buf_alloc),
> > +					le32_to_cpu(hdr->fwd_cnt));
> > +
> > +	if (!virtio_transport_valid_type(le16_to_cpu(hdr->type))) {
> > +		(void)virtio_transport_reset_no_sock(t, skb);
> > 		goto free_pkt;
> > 	}
> > 
> > @@ -1270,13 +1230,13 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
> > 	if (!sk) {
> > 		sk = vsock_find_bound_socket(&dst);
> > 		if (!sk) {
> > -			(void)virtio_transport_reset_no_sock(t, pkt);
> > +			(void)virtio_transport_reset_no_sock(t, skb);
> > 			goto free_pkt;
> > 		}
> > 	}
> > 
> > -	if (virtio_transport_get_type(sk) != le16_to_cpu(pkt->hdr.type)) {
> > -		(void)virtio_transport_reset_no_sock(t, pkt);
> > +	if (virtio_transport_get_type(sk) != le16_to_cpu(hdr->type)) {
> > +		(void)virtio_transport_reset_no_sock(t, skb);
> > 		sock_put(sk);
> > 		goto free_pkt;
> > 	}
> > @@ -1287,13 +1247,13 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
> > 
> > 	/* Check if sk has been closed before lock_sock */
> > 	if (sock_flag(sk, SOCK_DONE)) {
> > -		(void)virtio_transport_reset_no_sock(t, pkt);
> > +		(void)virtio_transport_reset_no_sock(t, skb);
> > 		release_sock(sk);
> > 		sock_put(sk);
> > 		goto free_pkt;
> > 	}
> > 
> > -	space_available = virtio_transport_space_update(sk, pkt);
> > +	space_available = virtio_transport_space_update(sk, skb);
> > 
> > 	/* Update CID in case it has changed after a transport reset event */
> > 	if (vsk->local_addr.svm_cid != VMADDR_CID_ANY)
> > @@ -1304,23 +1264,23 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
> > 
> > 	switch (sk->sk_state) {
> > 	case TCP_LISTEN:
> > -		virtio_transport_recv_listen(sk, pkt, t);
> > -		virtio_transport_free_pkt(pkt);
> > +		virtio_transport_recv_listen(sk, skb, t);
> > +		virtio_vsock_kfree_skb(skb);
> > 		break;
> > 	case TCP_SYN_SENT:
> > -		virtio_transport_recv_connecting(sk, pkt);
> > -		virtio_transport_free_pkt(pkt);
> > +		virtio_transport_recv_connecting(sk, skb);
> > +		virtio_vsock_kfree_skb(skb);
> > 		break;
> > 	case TCP_ESTABLISHED:
> > -		virtio_transport_recv_connected(sk, pkt);
> > +		virtio_transport_recv_connected(sk, skb);
> > 		break;
> > 	case TCP_CLOSING:
> > -		virtio_transport_recv_disconnecting(sk, pkt);
> > -		virtio_transport_free_pkt(pkt);
> > +		virtio_transport_recv_disconnecting(sk, skb);
> > +		virtio_vsock_kfree_skb(skb);
> > 		break;
> > 	default:
> > -		(void)virtio_transport_reset_no_sock(t, pkt);
> > -		virtio_transport_free_pkt(pkt);
> > +		(void)virtio_transport_reset_no_sock(t, skb);
> > +		virtio_vsock_kfree_skb(skb);
> > 		break;
> > 	}
> > 
> > @@ -1333,16 +1293,42 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
> > 	return;
> > 
> > free_pkt:
> > -	virtio_transport_free_pkt(pkt);
> > +	virtio_vsock_kfree_skb(skb);
> > }
> > EXPORT_SYMBOL_GPL(virtio_transport_recv_pkt);
> > 
> > -void virtio_transport_free_pkt(struct virtio_vsock_pkt *pkt)
> > +/* Remove skbs found in a queue that have a vsk that matches.
> > + *
> > + * Each skb is freed.
> > + *
> > + * Returns the count of skbs that were reply packets.
> > + */
> > +int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *queue)
> > {
> > -	kvfree(pkt->buf);
> > -	kfree(pkt);
> > +	struct sk_buff_head freeme;
> > +	struct sk_buff *skb, *tmp;
> > +	int cnt = 0;
> > +
> > +	skb_queue_head_init(&freeme);
> > +
> > +	spin_lock(&queue->lock);
> > +	skb_queue_walk_safe(queue, skb, tmp) {
> > +		if (vsock_sk(skb->sk) != vsk)
> > +			continue;
> > +
> > +		__skb_unlink(skb, queue);
> > +		skb_queue_tail(&freeme, skb);
> > +
> > +		if (virtio_vsock_skb_reply(skb))
> > +			cnt++;
> > +	}
> > +	spin_unlock(&queue->lock);
> > +
> > +	virtio_vsock_skb_queue_purge(&freeme);
> > +
> > +	return cnt;
> > }
> > -EXPORT_SYMBOL_GPL(virtio_transport_free_pkt);
> > +EXPORT_SYMBOL_GPL(virtio_transport_purge_skbs);
> > 
> > MODULE_LICENSE("GPL v2");
> > MODULE_AUTHOR("Asias He");
> > diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
> > index 169a8cf65b39..e57394579146 100644
> > --- a/net/vmw_vsock/vsock_loopback.c
> > +++ b/net/vmw_vsock/vsock_loopback.c
> > @@ -16,7 +16,7 @@ struct vsock_loopback {
> > 	struct workqueue_struct *workqueue;
> > 
> > 	spinlock_t pkt_list_lock; /* protects pkt_list */
> > -	struct list_head pkt_list;
> > +	struct sk_buff_head pkt_queue;
> > 	struct work_struct pkt_work;
> > };
> > 
> > @@ -27,13 +27,13 @@ static u32 vsock_loopback_get_local_cid(void)
> > 	return VMADDR_CID_LOCAL;
> > }
> > 
> > -static int vsock_loopback_send_pkt(struct virtio_vsock_pkt *pkt)
> > +static int vsock_loopback_send_pkt(struct sk_buff *skb)
> > {
> > 	struct vsock_loopback *vsock = &the_vsock_loopback;
> > -	int len = pkt->len;
> > +	int len = skb->len;
> > 
> > 	spin_lock_bh(&vsock->pkt_list_lock);
> > -	list_add_tail(&pkt->list, &vsock->pkt_list);
> > +	skb_queue_tail(&vsock->pkt_queue, skb);
> > 	spin_unlock_bh(&vsock->pkt_list_lock);
> > 
> > 	queue_work(vsock->workqueue, &vsock->pkt_work);
> > @@ -44,21 +44,8 @@ static int vsock_loopback_send_pkt(struct virtio_vsock_pkt *pkt)
> > static int vsock_loopback_cancel_pkt(struct vsock_sock *vsk)
> > {
> > 	struct vsock_loopback *vsock = &the_vsock_loopback;
> > -	struct virtio_vsock_pkt *pkt, *n;
> > -	LIST_HEAD(freeme);
> > 
> > -	spin_lock_bh(&vsock->pkt_list_lock);
> > -	list_for_each_entry_safe(pkt, n, &vsock->pkt_list, list) {
> > -		if (pkt->vsk != vsk)
> > -			continue;
> > -		list_move(&pkt->list, &freeme);
> > -	}
> > -	spin_unlock_bh(&vsock->pkt_list_lock);
> > -
> > -	list_for_each_entry_safe(pkt, n, &freeme, list) {
> > -		list_del(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > -	}
> > +	virtio_transport_purge_skbs(vsk, &vsock->pkt_queue);
> > 
> > 	return 0;
> > }
> > @@ -121,20 +108,18 @@ static void vsock_loopback_work(struct work_struct *work)
> > {
> > 	struct vsock_loopback *vsock =
> > 		container_of(work, struct vsock_loopback, pkt_work);
> > -	LIST_HEAD(pkts);
> > +	struct sk_buff_head pkts;
> > +	struct sk_buff *skb;
> > +
> > +	skb_queue_head_init(&pkts);
> > 
> > 	spin_lock_bh(&vsock->pkt_list_lock);
> > -	list_splice_init(&vsock->pkt_list, &pkts);
> > +	skb_queue_splice_init(&vsock->pkt_queue, &pkts);
> > 	spin_unlock_bh(&vsock->pkt_list_lock);
> > 
> > -	while (!list_empty(&pkts)) {
> > -		struct virtio_vsock_pkt *pkt;
> > -
> > -		pkt = list_first_entry(&pkts, struct virtio_vsock_pkt, list);
> > -		list_del_init(&pkt->list);
> > -
> > -		virtio_transport_deliver_tap_pkt(pkt);
> > -		virtio_transport_recv_pkt(&loopback_transport, pkt);
> > +	while ((skb = skb_dequeue(&pkts))) {
> > +		virtio_transport_deliver_tap_pkt(skb);
> > +		virtio_transport_recv_pkt(&loopback_transport, skb);
> > 	}
> > }
> > 
> > @@ -148,7 +133,7 @@ static int __init vsock_loopback_init(void)
> > 		return -ENOMEM;
> > 
> > 	spin_lock_init(&vsock->pkt_list_lock);
> > -	INIT_LIST_HEAD(&vsock->pkt_list);
> > +	skb_queue_head_init(&vsock->pkt_queue);
> > 	INIT_WORK(&vsock->pkt_work, vsock_loopback_work);
> > 
> > 	ret = vsock_core_register(&loopback_transport.transport,
> > @@ -166,19 +151,13 @@ static int __init vsock_loopback_init(void)
> > static void __exit vsock_loopback_exit(void)
> > {
> > 	struct vsock_loopback *vsock = &the_vsock_loopback;
> > -	struct virtio_vsock_pkt *pkt;
> > 
> > 	vsock_core_unregister(&loopback_transport.transport);
> > 
> > 	flush_work(&vsock->pkt_work);
> > 
> > 	spin_lock_bh(&vsock->pkt_list_lock);
> > -	while (!list_empty(&vsock->pkt_list)) {
> > -		pkt = list_first_entry(&vsock->pkt_list,
> > -				       struct virtio_vsock_pkt, list);
> > -		list_del(&pkt->list);
> > -		virtio_transport_free_pkt(pkt);
> > -	}
> > +	virtio_vsock_skb_queue_purge(&vsock->pkt_queue);
> > 	spin_unlock_bh(&vsock->pkt_list_lock);
> > 
> > 	destroy_workqueue(vsock->workqueue);
> > -- 
> > 2.20.1
> > 
> 
> 
> Good job, I left some comments on things to be fixed, but I think we are
> well on the way.
> 
> Next nice step to have (not in this patch/series) is to move packet queuing
> to the core and have all transports use skbuff (if they can).
> 
> Thanks,
> Stefano

Thanks for the review!