Re: [PATCH net-next v6] virtio/vsock: replace virtio_vsock_pkt with sk_buff

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On Tue, Dec 13, 2022 at 07:25:49AM +0000, 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%)

Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
---

Note: v6 was only tested from basic sanity checking in uperf, socat, and
the vsock_test tests in the mainline, but not the new tests from
Arseniy's test/vsock patches.

I tested with Arseniy's test/vsock patches applied and everything looks good!

I left just a couple of comments above based on Paolo review on v5 related to skb_queue_empty_lockless().


Changes in v6:
- use skb->cb instead of skb->_skb_refdst
- use lock-free __skb_queue_purge for rx_queue when rx_lock held

Changes in v5:
- last_skb instead of skb: last_hdr->len = cpu_to_le32(last_skb->len)

Changes in v4:
- vdso/bits.h -> linux/bits.h
- add virtio_vsock_alloc_skb() helper
- virtio/vsock: rename buf_len -> total_len
- update last_hdr->len
- fix build_skb() for vsockmon (tested)
- add queue helpers
- use spin_{unlock/lock}_bh() instead of spin_lock()/spin_unlock()
- note: I only ran a few g2h tests to check that this change
 had no perf impact. The above data is still from patch
 v3.

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.

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                   | 213 +++++-------
include/linux/virtio_vsock.h            | 132 ++++++--
net/vmw_vsock/virtio_transport.c        | 149 +++------
net/vmw_vsock/virtio_transport_common.c | 422 +++++++++++++-----------
net/vmw_vsock/vsock_loopback.c          |  51 +--
5 files changed, 501 insertions(+), 466 deletions(-)

drivers/vhost/vsock.c                   | 213 +++++-------
include/linux/virtio_vsock.h            | 132 ++++++--
net/vmw_vsock/virtio_transport.c        | 149 +++------
net/vmw_vsock/virtio_transport_common.c | 422 +++++++++++++-----------
net/vmw_vsock/vsock_loopback.c          |  51 +--
5 files changed, 501 insertions(+), 466 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 5703775af129..2a5994b029b2 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 +107,33 @@ 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);
+		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);
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
			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);
-
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
			/* We cannot finish yet if more buffers snuck in while
			 * re-enabling notify.
			 */
@@ -153,26 +145,27 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
		}

		if (out) {
-			virtio_transport_free_pkt(pkt);
+			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)) {
+			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 +178,30 @@ 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)) {
+			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);
+			kfree_skb(skb);
			vq_err(vq, "Faulted on copying pkt buf\n");
			break;
		}
@@ -217,31 +209,28 @@ 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);
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
		} else {
-			if (pkt->reply) {
+			if (virtio_vsock_skb_reply(skb)) {
				int val;

val = atomic_dec_return(&vsock->queued_replies);
@@ -253,7 +242,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
					restart_tx = true;
			}

-			virtio_transport_free_pkt(pkt);
+			consume_skb(skb);
		}
	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
	if (added)
@@ -278,28 +267,26 @@ 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);
+		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);
-
+	virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
	vhost_work_queue(&vsock->dev, &vsock->send_pkt_work);

	rcu_read_unlock();
@@ -310,10 +297,8 @@ 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 +307,7 @@ 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 +324,14 @@ 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 +340,47 @@ 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 = virtio_vsock_alloc_skb(len, GFP_KERNEL);
+	if (!skb)
		return NULL;

-	len = iov_length(vq->iov, out);
	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);
+		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) {
+		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);
+		kfree_skb(skb);
		return NULL;
	}

-	return pkt;
+	return skb;
}

/* Is there space left for replies to rx packets? */
@@ -496,9 +467,9 @@ 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 +482,8 @@ 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 +505,26 @@ 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);
+			kfree_skb(skb);

		vhost_add_used(vq, head, 0);
		added = true;
@@ -693,8 +668,7 @@ 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 +734,7 @@ 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..0385df976d41 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -3,10 +3,116 @@
#define _LINUX_VIRTIO_VSOCK_H

#include <uapi/linux/virtio_vsock.h>
+#include <linux/bits.h>
#include <linux/socket.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),
+};
+
+struct virtio_vsock_skb_cb {
+	bool reply;
+	bool tap_delivered;
+};
+
+#define VIRTIO_VSOCK_SKB_CB(skb) ((struct virtio_vsock_skb_cb *)((skb)->cb))
+
+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 VIRTIO_VSOCK_SKB_CB(skb)->reply;
+}
+
+static inline void virtio_vsock_skb_set_reply(struct sk_buff *skb)
+{
+	VIRTIO_VSOCK_SKB_CB(skb)->reply = true;
+}
+
+static inline bool virtio_vsock_skb_tap_delivered(struct sk_buff *skb)
+{
+	return VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered;
+}
+
+static inline void virtio_vsock_skb_set_tap_delivered(struct sk_buff *skb)
+{
+	VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = true;
+}
+
+static inline void virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
+{
+	VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
+}
+
+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 struct sk_buff *virtio_vsock_alloc_skb(unsigned int size, gfp_t mask)
+{
+	struct sk_buff *skb;
+
+	skb = alloc_skb(size, mask);
+	if (!skb)
+		return NULL;
+
+	skb_reserve(skb, VIRTIO_VSOCK_SKB_HEADROOM);
+	return skb;
+}
+
+static inline void
+virtio_vsock_skb_queue_head(struct sk_buff_head *list, struct sk_buff *skb)
+{
+	spin_lock_bh(&list->lock);
+	__skb_queue_head(list, skb);
+	spin_unlock_bh(&list->lock);
+}
+
+static inline void
+virtio_vsock_skb_queue_tail(struct sk_buff_head *list, struct sk_buff *skb)
+{
+	spin_lock_bh(&list->lock);
+	__skb_queue_tail(list, skb);
+	spin_unlock_bh(&list->lock);
+}
+
+static inline struct sk_buff *virtio_vsock_skb_dequeue(struct sk_buff_head *list)
+{
+	struct sk_buff *skb;
+
+	spin_lock_bh(&list->lock);
+	skb = __skb_dequeue(list);
+	spin_unlock_bh(&list->lock);
+
+	return skb;
+}
+
+static inline void virtio_vsock_skb_queue_purge(struct sk_buff_head *list)
+{
+	spin_lock_bh(&list->lock);
+	__skb_queue_purge(list);
+	spin_unlock_bh(&list->lock);
+}
+
+static inline size_t virtio_vsock_skb_len(struct sk_buff *skb)
+{
+	return (size_t)(skb_end_pointer(skb) - skb->head);
+}
+
#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 +141,10 @@ 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 +161,7 @@ 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 +242,10 @@ 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 *list);
#endif /* _LINUX_VIRTIO_VSOCK_H */
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index ad64f403536a..28b5a8e8e094 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 +100,31 @@ 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);
+		skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
+		if (!skb)
			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);

-		virtio_transport_deliver_tap_pkt(pkt);
+		virtio_transport_deliver_tap_pkt(skb);
+		reply = virtio_vsock_skb_reply(skb);

-		reply = pkt->reply;
-
-		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);
+			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
			break;
		}

@@ -164,32 +153,32 @@ 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);
+		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) {
+		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);
-
+	virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
	queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);

out_rcu:
@@ -201,9 +190,7 @@ 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 +199,7 @@ 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 +220,28 @@ 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 total_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE + 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 = virtio_vsock_alloc_skb(total_len, GFP_KERNEL);
+		if (!skb)
			break;

-		pkt->buf = kmalloc(buf_len, GFP_KERNEL);
-		if (!pkt->buf) {
-			virtio_transport_free_pkt(pkt);
+		memset(skb->head, 0, VIRTIO_VSOCK_SKB_HEADROOM);
+		sg_init_one(&pkt, virtio_vsock_hdr(skb), total_len);
+		p = &pkt;
+		ret = virtqueue_add_sgs(vq, &p, 0, 1, skb, GFP_KERNEL);
+		if (ret < 0) {
+			kfree_skb(skb);
			break;
		}

-		pkt->buf_len = buf_len;
-		pkt->len = buf_len;
-
-		sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
-		sgs[0] = &hdr;
-
-		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);
-			break;
-		}
		vsock->rx_buf_nr++;
	} while (vq->num_free);
	if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
@@ -299,12 +263,12 @@ 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) {
+			consume_skb(skb);
			added = true;
		}
	} while (!virtqueue_enable_cb(vq));
@@ -529,7 +493,7 @@ 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 +504,22 @@ 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))) {
+				kfree_skb(skb);
				continue;
			}

-			pkt->len = len - sizeof(pkt->hdr);
-			virtio_transport_deliver_tap_pkt(pkt);
- virtio_transport_recv_pkt(&virtio_transport, pkt);
+			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 +573,7 @@ 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 +600,16 @@ 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])))
+		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])))
+		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);
+	virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);

	/* Delete virtqueues and flush outstanding callbacks if any */
	vdev->config->del_vqs(vdev);
@@ -690,8 +646,7 @@ 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..3d2b9a4aefae 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -37,53 +37,56 @@ 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 = virtio_vsock_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;
+	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);

	if (info->msg && len > 0) {
-		pkt->buf = kmalloc(len, GFP_KERNEL);
-		if (!pkt->buf)
-			goto out_pkt;
-
-		pkt->buf_len = len;
-
-		err = memcpy_from_msg(pkt->buf, info->msg, len);
+		payload = skb_put(skb, len);
+		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,
@@ -91,19 +94,18 @@ 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);
+	kfree_skb(skb);
	return NULL;
}

/* Packet capture */
static struct sk_buff *virtio_transport_build_skb(void *opaque)
{
-	struct virtio_vsock_pkt *pkt = opaque;
+	struct virtio_vsock_hdr *pkt_hdr;
+	struct sk_buff *pkt = opaque;
	struct af_vsockmon_hdr *hdr;
	struct sk_buff *skb;
	size_t payload_len;
@@ -113,10 +115,11 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
	 * 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;
+	pkt_hdr = virtio_vsock_hdr(pkt);
+	payload_len = pkt->len;
+	payload_buf = pkt->data;

-	skb = alloc_skb(sizeof(*hdr) + sizeof(pkt->hdr) + payload_len,
+	skb = alloc_skb(sizeof(*hdr) + sizeof(*pkt_hdr) + payload_len,
			GFP_ATOMIC);
	if (!skb)
		return NULL;
@@ -124,16 +127,16 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
	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->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));
+	hdr->len = cpu_to_le16(sizeof(*pkt_hdr));
	memset(hdr->reserved, 0, sizeof(hdr->reserved));

-	switch (le16_to_cpu(pkt->hdr.op)) {
+	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);
@@ -154,7 +157,7 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
		break;
	}

-	skb_put_data(skb, &pkt->hdr, sizeof(pkt->hdr));
+	skb_put_data(skb, pkt_hdr, sizeof(*pkt_hdr));

	if (payload_len) {
		skb_put_data(skb, payload_buf, payload_len);
@@ -163,13 +166,13 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
	return skb;
}

-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 +195,8 @@ 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 +227,47 @@ 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 +311,29 @@ 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 +360,38 @@ 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)) {

As Paolo suggested on the v5, we should use skb_queue_empty() since we are under a lock (rx_lock) that is protecting the 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);
+			consume_skb(skb);
+		} else {
+			__skb_queue_head(&vvs->rx_queue, skb);
		}
	}

@@ -414,10 +423,10 @@ 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 +436,18 @@ 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 +458,7 @@ 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 +466,7 @@ 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 +476,16 @@ 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);
+		kfree_skb(skb);
	}

	spin_unlock_bh(&vvs->rx_lock);
@@ -609,7 +623,7 @@ 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 +820,16 @@ 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 +839,30 @@ 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);
+		kfree_skb(reply);
		return -ENOTCONN;
	}

@@ -858,16 +873,11 @@ 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);
-	}
-
+	__skb_queue_purge(&vvs->rx_queue);
	vsock_remove_sock(vsk);
}

@@ -981,13 +991,14 @@ 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 +1019,7 @@ 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 +1028,37 @@ 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)) {

Same here.

If there are no major changes to be made, I think the next version is the final ones, though we are now in the merge window, so net-next is closed [1], only RFCs can be sent [2].

I suggest you wait until the merge window is over (two weeks usually) to send the next version.

Thanks again for this great work!
Stefano

[1] http://vger.kernel.org/~davem/net-next.html
[2] https://www.kernel.org/doc/html/v6.0/process/maintainer-netdev.html#how-often-do-changes-from-these-trees-make-it-to-the-mainline-linus-tree

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