On Wed, Oct 05, 2022 at 06:19:44PM -0700, Bobby Eshleman wrote:
This patch replaces the struct virtio_vsock_pkt with struct sk_buff.

Using sk_buff in vsock benefits it by a) allowing vsock to be extended
for socket-related features like sockmap, b) vsock may in the future
use other sk_buff-dependent kernel capabilities, and c) vsock shares
commonality with other socket types.

This patch is taken from the original series found here:
https://lore.kernel.org/all/[email protected]/

Small-sized packet throughput improved by ~5% (from 18.53 Mb/s to 19.51
Mb/s). Tested using uperf, 16B payloads, 64 threads, 100s, averaged from
10 test runs (n=10). This improvement is likely due to packet merging.

Large-sized packet throughput decreases ~9% (from 27.25 Gb/s to 25.04
Gb/s). Tested using uperf, 64KB payloads, 64 threads, 100s, averaged
from 10 test runs (n=10).

Medium-sized packet throughput decreases ~5% (from 4.0 Gb/s to 3.81
Gb/s). Tested using uperf, 4k to 8k payload sizes picked randomly
according to normal distribution, 64 threads, 100s, averaged from 10
test runs (n=10).

All tests done in nested VMs (virtual host and virtual guest).

Signed-off-by: Bobby Eshleman <[email protected]>
---
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                   | 215 +++++------
include/linux/virtio_vsock.h            |  64 +++-
net/vmw_vsock/af_vsock.c                |   1 +
net/vmw_vsock/virtio_transport.c        | 206 +++++-----
net/vmw_vsock/virtio_transport_common.c | 483 ++++++++++++------------
net/vmw_vsock/vsock_loopback.c          |  51 +--
6 files changed, 504 insertions(+), 516 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 368330417bde..6179e637602f 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;

@@ -108,7 +107,8 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
        vhost_disable_notify(&vsock->dev, vq);

        do {
-               struct virtio_vsock_pkt *pkt;
+               struct sk_buff *skb;
+               struct virtio_vsock_hdr *hdr;

Reverse xmas tree is preferred in the net tree.
https://docs.kernel.org/process/maintainer-netdev.html?highlight=what+reverse+xmas+tree#what-is-reverse-xmas-tree

Please, check also in other places in this patch.

                struct iov_iter iov_iter;
                unsigned out, in;
                size_t nbytes;
@@ -116,31 +116,22 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
                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);
+               skb = skb_dequeue(&vsock->send_pkt_queue);
+
+               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);
+                       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);
+                       skb_queue_head(&vsock->send_pkt_queue, skb);

                        /* We cannot finish yet if more buffers snuck in while
                         * re-enabling notify.
@@ -153,26 +144,27 @@ 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 - vsock_metadata(skb)->off;

I guess the compiler will optimize, but what about store the metadata pointer in a variable?

+               hdr = 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 +177,31 @@ 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,
+               nbytes = copy_to_iter(skb->data + vsock_metadata(skb)->off, 
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;
+               vsock_metadata(skb)->off += 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 (vsock_metadata(skb)->off < skb->len) {
+                       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);
+                       vsock_metadata(skb)->flags &= 
~VIRTIO_VSOCK_METADATA_FLAGS_TAP_DELIVERED;
+                       skb_queue_head(&vsock->send_pkt_queue, skb);
                } else {
-                       if (pkt->reply) {
+                       if (vsock_metadata(skb)->flags & 
VIRTIO_VSOCK_METADATA_FLAGS_REPLY) {
                                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 vhost_vsock *vsock;
-       int len = pkt->len;
+       int len = skb->len;
+       struct virtio_vsock_hdr *hdr = vsock_hdr(skb);

        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 (vsock_metadata(skb)->flags & VIRTIO_VSOCK_METADATA_FLAGS_REPLY)
                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);
-
+       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];
@@ -352,11 +324,12 @@ 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 sk_buff *skb;
+       struct virtio_vsock_hdr *hdr;
        struct iov_iter iov_iter;
        size_t nbytes;
        size_t len;
@@ -366,50 +339,50 @@ 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, so only add additional space for 
metadata */
+       skb = alloc_skb(len + sizeof(struct virtio_vsock_metadata), GFP_KERNEL);
+       if (!skb)
                return NULL;

-       len = iov_length(vq->iov, out);
+       /* Only zero metadata, preserve the header */
+       memset(skb->head, 0, sizeof(struct virtio_vsock_metadata));
+       virtio_vsock_skb_reserve(skb);
        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 = 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);
+       len = le32_to_cpu(hdr->len);

        /* No payload */
-       if (!pkt->len)
-               return pkt;
+       if (!len)
+               return skb;

        /* The pkt is too big */
-       if (pkt->len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
-               kfree(pkt);
+       if (len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
+               kfree_skb(skb);
                return NULL;
        }

-       pkt->buf = kmalloc(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, len, &iov_iter);
+       if (nbytes != len) {
+               vq_err(vq, "Expected %zu byte payload, got %zu bytes\n",
+                      len, nbytes);
+               kfree_skb(skb);
                return NULL;
        }

-       return pkt;
+       return skb;
}

/* Is there space left for replies to rx packets? */
@@ -496,7 +469,7 @@ 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;
+       struct sk_buff *skb;
        int head, pkts = 0, total_len = 0;
        unsigned int out, in;
        bool added = false;
@@ -511,6 +484,9 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work 
*work)

        vhost_disable_notify(&vsock->dev, vq);
        do {
+               struct virtio_vsock_hdr *hdr;
+               u32 len;
+
                if (!vhost_vsock_more_replies(vsock)) {
                        /* Stop tx until the device processes already
                         * pending replies.  Leave tx virtqueue
@@ -532,26 +508,29 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work 
*work)
                        break;
                }

-               pkt = vhost_vsock_alloc_pkt(vq, out, in);
-               if (!pkt) {
-                       vq_err(vq, "Faulted on pkt\n");
+               skb = vhost_vsock_alloc_skb(vq, out, in);
+               if (!skb)
                        continue;
-               }

-               total_len += sizeof(pkt->hdr) + pkt->len;
+               len = skb->len;

                /* Deliver to monitoring devices all received packets */
-               virtio_transport_deliver_tap_pkt(pkt);
+               virtio_transport_deliver_tap_pkt(skb);
+
+               hdr = 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);
+               len += sizeof(*hdr);
+               vhost_add_used(vq, head, len);

Please don't use `len` in vhost_add_used(). We should pass the number of bytes written by the device. Take a look at https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=49d8c5ffad07ca014cfae72a1b9b8c52b6ad9cb8

Maybe we should document better vhost_add_used() to avoid future issue.

+               total_len += len;
                added = true;
        } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));

@@ -693,8 +672,7 @@ 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 +738,7 @@ 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);
+       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..b1dff55c91a5 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -4,9 +4,47 @@

#include <uapi/linux/virtio_vsock.h>
#include <linux/socket.h>
+#include <vdso/bits.h>
#include <net/sock.h>
#include <net/af_vsock.h>

+/* Threshold for detecting small packets to copy */
+#define GOOD_COPY_LEN  128

Since we moved this in an header, I guess is better to add a prefix (e.g. VIRTIO_VSOCK_GOOD_COPY_LEN)

+
+enum virtio_vsock_metadata_flags {
+       VIRTIO_VSOCK_METADATA_FLAGS_REPLY               = BIT(0),
+       VIRTIO_VSOCK_METADATA_FLAGS_TAP_DELIVERED       = BIT(1),
+};
+
+/* Used only by the virtio/vhost vsock drivers, not related to protocol */
+struct virtio_vsock_metadata {
+       size_t off;
+       enum virtio_vsock_metadata_flags flags;
+};
+
+#define vsock_hdr(skb) \

For uniformity better virtio_vsock_get_hdr()

+       ((struct virtio_vsock_hdr *) \
+        ((void *)skb->head + sizeof(struct virtio_vsock_metadata)))
+
+#define vsock_metadata(skb) \

Ditto

+       ((struct virtio_vsock_metadata *)skb->head)
+
+#define VIRTIO_VSOCK_SKB_RESERVE_SIZE \
+       (sizeof(struct virtio_vsock_metadata) + sizeof(struct virtio_vsock_hdr))
+
+#define virtio_vsock_skb_reserve(skb) \
+       skb_reserve(skb, VIRTIO_VSOCK_SKB_RESERVE_SIZE)
+
+static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
+{
+       u32 len;
+
+       len = le32_to_cpu(vsock_hdr(skb)->len);
+
+       if (len > 0)
+               skb_put(skb, len);
+}
+
#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 +73,10 @@ 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 +93,7 @@ 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 +174,10 @@ 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/af_vsock.c b/net/vmw_vsock/af_vsock.c
index b4ee163154a6..de8a9b0ec3a0 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -748,6 +748,7 @@ static struct sock *__vsock_create(struct net *net,
        vsock_addr_init(&vsk->local_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);
        vsock_addr_init(&vsk->remote_addr, VMADDR_CID_ANY, VMADDR_PORT_ANY);

+       sk->sk_allocation = GFP_KERNEL;

This will change also other transports, like VMCI that uses sk_buff for datagram. We should check that it is okay for them.

        sk->sk_destruct = vsock_sk_destruct;
        sk->sk_backlog_rcv = vsock_queue_rcv_skb;
        sock_reset_flag(sk, SOCK_DONE);
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index ad64f403536a..ac8c7003835b 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -21,6 +21,11 @@
#include <linux/mutex.h>
#include <net/af_vsock.h>

+#define VIRTIO_VSOCK_MAX_RX_HDR_PAYLOAD_SIZE   \
+       (VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE \
+                - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) \
+                - VIRTIO_VSOCK_SKB_RESERVE_SIZE)
+
static struct workqueue_struct *virtio_vsock_workqueue;
static struct virtio_vsock __rcu *the_virtio_vsock;
static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
@@ -42,8 +47,7 @@ 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 +105,32 @@ virtio_transport_send_pkt_work(struct work_struct *work)
        vq = vsock->vqs[VSOCK_VQ_TX];

        for (;;) {
-               struct virtio_vsock_pkt *pkt;
+               struct sk_buff *skb;
                struct scatterlist hdr, buf, *sgs[2];
                int ret, in_sg = 0, out_sg = 0;
                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;
-               }
+               skb = skb_dequeue(&vsock->send_pkt_queue);

-               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);
+               if (!skb)
+                       break;

-               reply = pkt->reply;
+               virtio_transport_deliver_tap_pkt(skb);
+               reply = vsock_metadata(skb)->flags & 
VIRTIO_VSOCK_METADATA_FLAGS_REPLY;

-               sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
+               sg_init_one(&hdr, vsock_hdr(skb), sizeof(*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);
+                       skb_queue_head(&vsock->send_pkt_queue, skb);
                        break;
                }

@@ -163,33 +158,83 @@ virtio_transport_send_pkt_work(struct work_struct *work)
                queue_work(virtio_vsock_workqueue, &vsock->rx_work);
}

+static inline bool
+virtio_transport_skbs_can_merge(struct sk_buff *old, struct sk_buff *new)
+{
+       return (new->len < GOOD_COPY_LEN &&
+               skb_tailroom(old) >= new->len &&
+               vsock_hdr(new)->src_cid == vsock_hdr(old)->src_cid &&
+               vsock_hdr(new)->dst_cid == vsock_hdr(old)->dst_cid &&
+               vsock_hdr(new)->src_port == vsock_hdr(old)->src_port &&
+               vsock_hdr(new)->dst_port == vsock_hdr(old)->dst_port &&

For these first fields perhaps we can use a memcmp.

Can we use a pointer to store the header pointers?

+               vsock_hdr(new)->type == vsock_hdr(old)->type &&
+               vsock_hdr(new)->flags == vsock_hdr(old)->flags &&
+               le16_to_cpu(vsock_hdr(old)->op) == VIRTIO_VSOCK_OP_RW &&
+               le16_to_cpu(vsock_hdr(new)->op) == VIRTIO_VSOCK_OP_RW);
+}
+
+/* Add new sk_buff to queue.
+ *
+ * Merge the two most recent skbs together if possible.
+ */
+static void
+virtio_transport_add_to_queue(struct sk_buff_head *queue, struct sk_buff *new)
+{
+       struct sk_buff *old;
+
+       spin_lock_bh(&queue->lock);
+       if (skb_queue_empty_lockless(queue)) {
+               __skb_queue_tail(queue, new);
+               goto out;
+       }
+
+       old = skb_peek_tail(queue);
+
+ /* In order to reduce skb memory overhead, we merge new packets with
+        * older packets if they pass virtio_transport_skbs_can_merge().
+        */
+       if (!virtio_transport_skbs_can_merge(old, new)) {
+               __skb_queue_tail(queue, new);
+               goto out;
+       }
+
+       memcpy(skb_put(old, new->len), new->data, new->len);

This extra copy (and maybe also the call to can_merge) could be responsible for the perf drop. I understand why we have it, though, you could give it a try by avoiding merging and see what happens to performance.

Maybe we can split this patch and move change in a separate patch of the same series, and in the cover report the performance result incrementally with only the first patch applied and with first and second.

+       vsock_hdr(old)->len = cpu_to_le32(old->len);
+       vsock_hdr(old)->buf_alloc = vsock_hdr(new)->buf_alloc;
+       vsock_hdr(old)->fwd_cnt = vsock_hdr(new)->fwd_cnt;
+       dev_kfree_skb_any(new);
+
+out:
+       spin_unlock_bh(&queue->lock);
+}
+
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 = 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 (vsock_metadata(skb)->flags & VIRTIO_VSOCK_METADATA_FLAGS_REPLY)
                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_transport_add_to_queue(&vsock->send_pkt_queue, skb);
        queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);

out_rcu:
@@ -201,9 +246,7 @@ 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 +255,7 @@ 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 +276,32 @@ 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];
+       struct scatterlist pkt, *sgs[1];
        struct virtqueue *vq;
        int ret;

        vq = vsock->vqs[VSOCK_VQ_RX];

        do {
-               pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
-               if (!pkt)
-                       break;
+               struct sk_buff *skb;
+               const size_t len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE -
+                               SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

-               pkt->buf = kmalloc(buf_len, GFP_KERNEL);
-               if (!pkt->buf) {
-                       virtio_transport_free_pkt(pkt);
+               skb = alloc_skb(len, GFP_KERNEL);
+               if (!skb)
                        break;
-               }

-               pkt->buf_len = buf_len;
-               pkt->len = buf_len;
+               memset(skb->head, 0, VIRTIO_VSOCK_SKB_RESERVE_SIZE);

-               sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
-               sgs[0] = &hdr;
+               sg_init_one(&pkt, vsock_hdr(skb), 
VIRTIO_VSOCK_MAX_RX_HDR_PAYLOAD_SIZE);
+               sgs[0] = &pkt;

-               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);
+               ret = virtqueue_add_sgs(vq, sgs, 0, 1, skb, GFP_KERNEL);
+               if (ret < 0) {
+                       kfree_skb(skb);
                        break;
                }
+
                vsock->rx_buf_nr++;
        } while (vq->num_free);
        if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
@@ -299,12 +323,12 @@ 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 +553,7 @@ 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 +564,23 @@ 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_MAX_RX_HDR_PAYLOAD_SIZE)) {
+                               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_reserve(skb);
+                       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 +634,7 @@ 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 +661,16 @@ 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);
+       skb_queue_purge(&vsock->send_pkt_queue);

        /* Delete virtqueues and flush outstanding callbacks if any */
        vdev->config->del_vqs(vdev);
@@ -690,8 +707,7 @@ 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 ec2c2afbf0d0..19678bd45c23 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -23,9 +23,6 @@
/* How long to wait for graceful shutdown of a connection */
#define VSOCK_CLOSE_TIMEOUT (8 * HZ)

-/* Threshold for detecting small packets to copy */
-#define GOOD_COPY_LEN  128
-
static const struct virtio_transport *
virtio_transport_get_ops(struct vsock_sock *vsk)
{
@@ -37,53 +34,64 @@ 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)
+                          u32 dst_port,
+                          int *errp)
{
-       struct virtio_vsock_pkt *pkt;
+       struct sk_buff *skb;
+       struct virtio_vsock_hdr *hdr;
+       void *payload;
+       const size_t skb_len = VIRTIO_VSOCK_SKB_RESERVE_SIZE + len;
        int err;

-       pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
-       if (!pkt)
+       skb = alloc_skb(skb_len, GFP_KERNEL);
+       if (!skb) {
+               *errp = -ENOMEM;
                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;
-
-       if (info->msg && len > 0) {
-               pkt->buf = kmalloc(len, GFP_KERNEL);
-               if (!pkt->buf)
-                       goto out_pkt;
+       memset(skb->head, 0, VIRTIO_VSOCK_SKB_RESERVE_SIZE);
+       virtio_vsock_skb_reserve(skb);
+       payload = skb_put(skb, len);

-               pkt->buf_len = len;
+       hdr = 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 (err)
+       if (info->msg && len > 0) {
+               err = memcpy_from_msg(payload, info->msg, len);
+               if (err) {
+                       *errp = -ENOMEM;
                        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)
+               vsock_metadata(skb)->flags |= VIRTIO_VSOCK_METADATA_FLAGS_REPLY;
+
        trace_virtio_transport_alloc_pkt(src_cid, src_port,
                                         dst_cid, dst_port,
                                         len,
@@ -91,85 +99,26 @@ 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);
+       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_clone((struct sk_buff *)opaque, GFP_ATOMIC);
}

-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 (vsock_metadata(skb)->flags & 
VIRTIO_VSOCK_METADATA_FLAGS_TAP_DELIVERED)
                return;

-       vsock_deliver_tap(virtio_transport_build_skb, pkt);
-       pkt->tap_delivered = true;
+       vsock_deliver_tap(virtio_transport_build_skb, skb);
+       vsock_metadata(skb)->flags |= VIRTIO_VSOCK_METADATA_FLAGS_TAP_DELIVERED;
}
EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);

@@ -192,8 +141,9 @@ 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;
+       struct sk_buff *skb;
        u32 pkt_len = info->pkt_len;
+       int err;

        info->type = virtio_transport_get_type(sk_vsock(vsk));

@@ -224,42 +174,47 @@ 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) {
+                                        dst_cid, dst_port,
+                                        &err);
+       if (!skb) {
                virtio_transport_put_credit(vvs, pkt_len);
-               return -ENOMEM;
+               return err;
        }

-       virtio_transport_inc_tx_pkt(vvs, pkt);
+       virtio_transport_inc_tx_pkt(vvs, skb);
+
+       err = t_ops->send_pkt(skb);

-       return t_ops->send_pkt(pkt);
+       return err < 0 ? -ENOMEM : err;
}

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;
+       vvs->rx_bytes -= skb->len;
+       vvs->fwd_cnt += skb->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 = 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 +258,29 @@ virtio_transport_stream_do_peek(struct vsock_sock *vsk,
                                size_t len)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
-       struct virtio_vsock_pkt *pkt;
+       struct sk_buff *skb, *tmp;
        size_t bytes, total = 0, off;
        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 = vsock_metadata(skb)->off;

                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 +307,40 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
                                   size_t len)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
-       struct virtio_vsock_pkt *pkt;
+       struct sk_buff *skb;
        size_t bytes, total = 0;
        u32 free_space;
        int err = -EFAULT;

        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 - vsock_metadata(skb)->off)
+                       bytes = skb->len - vsock_metadata(skb)->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 + pkt->off, bytes);
+               err = memcpy_to_msg(msg, skb->data + vsock_metadata(skb)->off, 
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);
+               vsock_metadata(skb)->off += bytes;
+
+               WARN_ON(vsock_metadata(skb)->off > skb->len);
                ^
Can this ever happen?

+
+               if (vsock_metadata(skb)->off == skb->len) {
+                       virtio_transport_dec_rx_pkt(vvs, skb);
+                       consume_skb(skb);
+               } else {
+                       __skb_queue_head(&vvs->rx_queue, skb);
                }
        }

@@ -414,7 +372,7 @@ 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;
+       struct sk_buff *skb;
        int dequeued_len = 0;
        size_t user_buf_len = msg_data_left(msg);
        bool msg_ready = false;
@@ -426,14 +384,24 @@ static int virtio_transport_seqpacket_do_dequeue(struct 
vsock_sock *vsk,
                return 0;
        }

+       if (skb_queue_empty_lockless(&vvs->rx_queue)) {
+               spin_unlock_bh(&vvs->rx_lock);
+               return 0;
+       }
+
        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 = 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 +412,7 @@ 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.
@@ -461,17 +429,16 @@ 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 +576,7 @@ 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;
}
@@ -809,16 +776,16 @@ 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(vsock_hdr(skb)->op) == VIRTIO_VSOCK_OP_RST)
                return 0;

        return virtio_transport_send_pkt_info(vsk, &info);
@@ -828,29 +795,32 @@ 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 sk_buff *reply;
+       struct virtio_vsock_hdr *hdr = 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,
        };
+       int err;

        /* 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),
+                                          &err);
        if (!reply)
-               return -ENOMEM;
+               return err;

        if (!t) {
-               virtio_transport_free_pkt(reply);
+               kfree_skb(reply);
                return -ENOTCONN;
        }

@@ -861,16 +831,11 @@ 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);
}

@@ -984,13 +949,14 @@ 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 vsock_sock *vsk = vsock_sk(sk);
+       struct virtio_vsock_hdr *hdr = vsock_hdr(skb);
        int err;
        int skerr;

-       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;
@@ -1011,7 +977,7 @@ 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);
@@ -1020,34 +986,38 @@ 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;
+       struct virtio_vsock_hdr *hdr;
        bool can_enqueue, free_pkt = false;
+       u32 len;

-       pkt->len = le32_to_cpu(pkt->hdr.len);
-       pkt->off = 0;
+       hdr = vsock_hdr(skb);
+       len = le32_to_cpu(hdr->len);
+       vsock_metadata(skb)->off = 0;

        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 = 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
@@ -1055,35 +1025,34 @@ 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_EOR)) {
+                       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);
+               kfree_skb(skb);
}

static int
virtio_transport_recv_connected(struct sock *sk,
-                               struct virtio_vsock_pkt *pkt)
+                               struct sk_buff *skb)
{
        struct vsock_sock *vsk = vsock_sk(sk);
+       struct virtio_vsock_hdr *hdr = vsock_hdr(skb);
        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);
                sk->sk_data_ready(sk);
                return err;
        case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
@@ -1093,18 +1062,17 @@ 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(vsock_hdr(skb)->flags))
                        sk->sk_state_change(sk);
                break;
        case VIRTIO_VSOCK_OP_RST:
@@ -1115,28 +1083,30 @@ virtio_transport_recv_connected(struct sock *sk,
                break;
        }

-       virtio_transport_free_pkt(pkt);
+       kfree_skb(skb);
        return err;
}

static void
virtio_transport_recv_disconnecting(struct sock *sk,
-                                   struct virtio_vsock_pkt *pkt)
+                                   struct sk_buff *skb)
{
        struct vsock_sock *vsk = vsock_sk(sk);
+       struct virtio_vsock_hdr *hdr = vsock_hdr(skb);

-       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 = 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,
        };
@@ -1145,10 +1115,11 @@ 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 vsock_sock *vsk = vsock_sk(sk);
        struct virtio_vsock_sock *vvs = vsk->trans;
+       struct virtio_vsock_hdr *hdr = vsock_hdr(skb);
        bool space_available;

        /* Listener sockets are not associated with any transport, so we are
@@ -1161,8 +1132,8 @@ 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;
@@ -1170,27 +1141,28 @@ 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 vsock_sock *vsk = vsock_sk(sk);
+       struct virtio_vsock_hdr *hdr = vsock_hdr(skb);
        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;
        }

@@ -1201,10 +1173,10 @@ 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
@@ -1212,17 +1184,17 @@ 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);

@@ -1240,29 +1212,30 @@ 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 sockaddr_vm src, dst;
        struct vsock_sock *vsk;
        struct sock *sk;
        bool space_available;
+       struct virtio_vsock_hdr *hdr = vsock_hdr(skb);

-       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;
        }

@@ -1273,13 +1246,13 @@ 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;
        }
@@ -1290,13 +1263,13 @@ 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)
@@ -1307,23 +1280,23 @@ 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);
+               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);
+               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);
+               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);
+               kfree_skb(skb);
                break;
        }

@@ -1336,16 +1309,42 @@ void virtio_transport_recv_pkt(struct virtio_transport 
*t,
        return;

free_pkt:
-       virtio_transport_free_pkt(pkt);
+       kfree(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)
{
-       kfree(pkt->buf);
-       kfree(pkt);
+       int cnt = 0;
+       struct sk_buff *skb, *tmp;
+       struct sk_buff_head freeme;
+
+       skb_queue_head_init(&freeme);
+
+       spin_lock_bh(&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 (vsock_metadata(skb)->flags & 
VIRTIO_VSOCK_METADATA_FLAGS_REPLY)
+                       cnt++;
+       }
+       spin_unlock_bh(&queue->lock);
+
+       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..792128e66869 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);
-       }
+       skb_queue_purge(&vsock->pkt_queue);
        spin_unlock_bh(&vsock->pkt_list_lock);

        destroy_workqueue(vsock->workqueue);
--
2.35.1


Not for this patch, but if we implement this change, it would be nice to have APIs that all transports can re-use. (Like we do in vsock_loopback which has nothing to do with virtio, but we had reused virtio_vsock_pkt for convenience)

Good job so far!

Thanks,
Stefano

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