Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1415 insertions, 0 deletions

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
new file mode 100644
index 000000000..9983b833b
--- /dev/null
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -0,0 +1,1415 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * common code for virtio vsock
+ *
+ * Copyright (C) 2013-2015 Red Hat, Inc.
+ * Author: Asias He <asias@redhat.com>
+ *         Stefan Hajnoczi <stefanha@redhat.com>
+ */
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/sched/signal.h>
+#include <linux/ctype.h>
+#include <linux/list.h>
+#include <linux/virtio_vsock.h>
+#include <uapi/linux/vsockmon.h>
+
+#include <net/sock.h>
+#include <net/af_vsock.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/vsock_virtio_transport_common.h>
+
+/* 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)
+{
+	const struct vsock_transport *t = vsock_core_get_transport(vsk);
+
+	if (WARN_ON(!t))
+		return NULL;
+
+	return container_of(t, struct virtio_transport, transport);
+}
+
+/* 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)
+{
+	const size_t skb_len = VIRTIO_VSOCK_SKB_HEADROOM + len;
+	struct virtio_vsock_hdr *hdr;
+	struct sk_buff *skb;
+	void *payload;
+	int err;
+
+	skb = virtio_vsock_alloc_skb(skb_len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	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);
+	hdr->buf_alloc	= cpu_to_le32(0);
+	hdr->fwd_cnt	= cpu_to_le32(0);
+
+	if (info->msg && len > 0) {
+		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) {
+			hdr->flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
+
+			if (info->msg->msg_flags & MSG_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,
+					 info->type,
+					 info->op,
+					 info->flags);
+
+	if (info->vsk && !skb_set_owner_sk_safe(skb, sk_vsock(info->vsk))) {
+		WARN_ONCE(1, "failed to allocate skb on vsock socket with sk_refcnt == 0\n");
+		goto out;
+	}
+
+	return skb;
+
+out:
+	kfree_skb(skb);
+	return NULL;
+}
+
+/* Packet capture */
+static struct sk_buff *virtio_transport_build_skb(void *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;
+	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.
+	 */
+	pkt_hdr = virtio_vsock_hdr(pkt);
+	payload_len = pkt->len;
+	payload_buf = pkt->data;
+
+	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;
+}
+
+void virtio_transport_deliver_tap_pkt(struct sk_buff *skb)
+{
+	if (virtio_vsock_skb_tap_delivered(skb))
+		return;
+
+	vsock_deliver_tap(virtio_transport_build_skb, skb);
+	virtio_vsock_skb_set_tap_delivered(skb);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);
+
+static u16 virtio_transport_get_type(struct sock *sk)
+{
+	if (sk->sk_type == SOCK_STREAM)
+		return VIRTIO_VSOCK_TYPE_STREAM;
+	else
+		return VIRTIO_VSOCK_TYPE_SEQPACKET;
+}
+
+/* This function can only be used on connecting/connected sockets,
+ * since a socket assigned to a transport is required.
+ *
+ * Do not use on listener sockets!
+ */
+static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
+					  struct virtio_vsock_pkt_info *info)
+{
+	u32 src_cid, src_port, dst_cid, dst_port;
+	const struct virtio_transport *t_ops;
+	struct virtio_vsock_sock *vvs;
+	u32 pkt_len = info->pkt_len;
+	struct sk_buff *skb;
+
+	info->type = virtio_transport_get_type(sk_vsock(vsk));
+
+	t_ops = virtio_transport_get_ops(vsk);
+	if (unlikely(!t_ops))
+		return -EFAULT;
+
+	src_cid = t_ops->transport.get_local_cid();
+	src_port = vsk->local_addr.svm_port;
+	if (!info->remote_cid) {
+		dst_cid	= vsk->remote_addr.svm_cid;
+		dst_port = vsk->remote_addr.svm_port;
+	} else {
+		dst_cid = info->remote_cid;
+		dst_port = info->remote_port;
+	}
+
+	vvs = vsk->trans;
+
+	/* we can send less than pkt_len bytes */
+	if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
+		pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;
+
+	/* virtio_transport_get_credit might return less than pkt_len credit */
+	pkt_len = virtio_transport_get_credit(vvs, pkt_len);
+
+	/* Do not send zero length OP_RW pkt */
+	if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
+		return pkt_len;
+
+	skb = virtio_transport_alloc_skb(info, pkt_len,
+					 src_cid, src_port,
+					 dst_cid, dst_port);
+	if (!skb) {
+		virtio_transport_put_credit(vvs, pkt_len);
+		return -ENOMEM;
+	}
+
+	virtio_transport_inc_tx_pkt(vvs, skb);
+
+	return t_ops->send_pkt(skb);
+}
+
+static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
+					u32 len)
+{
+	if (vvs->rx_bytes + len > vvs->buf_alloc)
+		return false;
+
+	vvs->rx_bytes += len;
+	return true;
+}
+
+static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
+					u32 len)
+{
+	vvs->rx_bytes -= len;
+	vvs->fwd_cnt += len;
+}
+
+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;
+	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);
+
+u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 credit)
+{
+	u32 ret;
+
+	spin_lock_bh(&vvs->tx_lock);
+	ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
+	if (ret > credit)
+		ret = credit;
+	vvs->tx_cnt += ret;
+	spin_unlock_bh(&vvs->tx_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_get_credit);
+
+void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit)
+{
+	spin_lock_bh(&vvs->tx_lock);
+	vvs->tx_cnt -= credit;
+	spin_unlock_bh(&vvs->tx_lock);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_put_credit);
+
+static int virtio_transport_send_credit_update(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_CREDIT_UPDATE,
+		.vsk = vsk,
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+
+static ssize_t
+virtio_transport_stream_do_peek(struct vsock_sock *vsk,
+				struct msghdr *msg,
+				size_t len)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	size_t bytes, total = 0, off;
+	struct sk_buff *skb, *tmp;
+	int err = -EFAULT;
+
+	spin_lock_bh(&vvs->rx_lock);
+
+	skb_queue_walk_safe(&vvs->rx_queue, skb,  tmp) {
+		off = 0;
+
+		if (total == len)
+			break;
+
+		while (total < len && off < skb->len) {
+			bytes = len - total;
+			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, skb->data + off, bytes);
+			if (err)
+				goto out;
+
+			spin_lock_bh(&vvs->rx_lock);
+
+			total += bytes;
+			off += bytes;
+		}
+	}
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return total;
+
+out:
+	if (total)
+		err = total;
+	return err;
+}
+
+static ssize_t
+virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   size_t len)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	size_t bytes, total = 0;
+	struct sk_buff *skb;
+	u32 fwd_cnt_delta;
+	bool low_rx_bytes;
+	int err = -EFAULT;
+	u32 free_space;
+
+	spin_lock_bh(&vvs->rx_lock);
+	while (total < len && !skb_queue_empty(&vvs->rx_queue)) {
+		skb = skb_peek(&vvs->rx_queue);
+
+		bytes = len - total;
+		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, skb->data, bytes);
+		if (err)
+			goto out;
+
+		spin_lock_bh(&vvs->rx_lock);
+
+		total += bytes;
+		skb_pull(skb, bytes);
+
+		if (skb->len == 0) {
+			u32 pkt_len = le32_to_cpu(virtio_vsock_hdr(skb)->len);
+
+			virtio_transport_dec_rx_pkt(vvs, pkt_len);
+			__skb_unlink(skb, &vvs->rx_queue);
+			consume_skb(skb);
+		}
+	}
+
+	fwd_cnt_delta = vvs->fwd_cnt - vvs->last_fwd_cnt;
+	free_space = vvs->buf_alloc - fwd_cnt_delta;
+	low_rx_bytes = (vvs->rx_bytes <
+			sock_rcvlowat(sk_vsock(vsk), 0, INT_MAX));
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	/* To reduce the number of credit update messages,
+	 * don't update credits as long as lots of space is available.
+	 * Note: the limit chosen here is arbitrary. Setting the limit
+	 * too high causes extra messages. Too low causes transmitter
+	 * stalls. As stalls are in theory more expensive than extra
+	 * messages, we set the limit to a high value. TODO: experiment
+	 * with different values. Also send credit update message when
+	 * number of bytes in rx queue is not enough to wake up reader.
+	 */
+	if (fwd_cnt_delta &&
+	    (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE || low_rx_bytes))
+		virtio_transport_send_credit_update(vsk);
+
+	return total;
+
+out:
+	if (total)
+		err = total;
+	return err;
+}
+
+static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
+						 struct msghdr *msg,
+						 int flags)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	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);
+
+	if (vvs->msg_count == 0) {
+		spin_unlock_bh(&vvs->rx_lock);
+		return 0;
+	}
+
+	while (!msg_ready) {
+		struct virtio_vsock_hdr *hdr;
+		size_t pkt_len;
+
+		skb = __skb_dequeue(&vvs->rx_queue);
+		if (!skb)
+			break;
+		hdr = virtio_vsock_hdr(skb);
+		pkt_len = (size_t)le32_to_cpu(hdr->len);
+
+		if (dequeued_len >= 0) {
+			size_t bytes_to_copy;
+
+			bytes_to_copy = min(user_buf_len, pkt_len);
+
+			if (bytes_to_copy) {
+				int err;
+
+				/* 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, skb->data, bytes_to_copy);
+				if (err) {
+					/* Copy of message failed. Rest of
+					 * fragments will be freed without copy.
+					 */
+					dequeued_len = err;
+				} else {
+					user_buf_len -= bytes_to_copy;
+				}
+
+				spin_lock_bh(&vvs->rx_lock);
+			}
+
+			if (dequeued_len >= 0)
+				dequeued_len += pkt_len;
+		}
+
+		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
+			msg_ready = true;
+			vvs->msg_count--;
+
+			if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR)
+				msg->msg_flags |= MSG_EOR;
+		}
+
+		virtio_transport_dec_rx_pkt(vvs, pkt_len);
+		kfree_skb(skb);
+	}
+
+	spin_unlock_bh(&vvs->rx_lock);
+
+	virtio_transport_send_credit_update(vsk);
+
+	return dequeued_len;
+}
+
+ssize_t
+virtio_transport_stream_dequeue(struct vsock_sock *vsk,
+				struct msghdr *msg,
+				size_t len, int flags)
+{
+	if (flags & MSG_PEEK)
+		return virtio_transport_stream_do_peek(vsk, msg, len);
+	else
+		return virtio_transport_stream_do_dequeue(vsk, msg, len);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_dequeue);
+
+ssize_t
+virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   int flags)
+{
+	if (flags & MSG_PEEK)
+		return -EOPNOTSUPP;
+
+	return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);
+
+int
+virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
+				   struct msghdr *msg,
+				   size_t len)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	spin_lock_bh(&vvs->tx_lock);
+
+	if (len > vvs->peer_buf_alloc) {
+		spin_unlock_bh(&vvs->tx_lock);
+		return -EMSGSIZE;
+	}
+
+	spin_unlock_bh(&vvs->tx_lock);
+
+	return virtio_transport_stream_enqueue(vsk, msg, len);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);
+
+int
+virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
+			       struct msghdr *msg,
+			       size_t len, int flags)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);
+
+s64 virtio_transport_stream_has_data(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	s64 bytes;
+
+	spin_lock_bh(&vvs->rx_lock);
+	bytes = vvs->rx_bytes;
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_has_data);
+
+u32 virtio_transport_seqpacket_has_data(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	u32 msg_count;
+
+	spin_lock_bh(&vvs->rx_lock);
+	msg_count = vvs->msg_count;
+	spin_unlock_bh(&vvs->rx_lock);
+
+	return msg_count;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_has_data);
+
+static s64 virtio_transport_has_space(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	s64 bytes;
+
+	bytes = (s64)vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
+	if (bytes < 0)
+		bytes = 0;
+
+	return bytes;
+}
+
+s64 virtio_transport_stream_has_space(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	s64 bytes;
+
+	spin_lock_bh(&vvs->tx_lock);
+	bytes = virtio_transport_has_space(vsk);
+	spin_unlock_bh(&vvs->tx_lock);
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_has_space);
+
+int virtio_transport_do_socket_init(struct vsock_sock *vsk,
+				    struct vsock_sock *psk)
+{
+	struct virtio_vsock_sock *vvs;
+
+	vvs = kzalloc(sizeof(*vvs), GFP_KERNEL);
+	if (!vvs)
+		return -ENOMEM;
+
+	vsk->trans = vvs;
+	vvs->vsk = vsk;
+	if (psk && psk->trans) {
+		struct virtio_vsock_sock *ptrans = psk->trans;
+
+		vvs->peer_buf_alloc = ptrans->peer_buf_alloc;
+	}
+
+	if (vsk->buffer_size > VIRTIO_VSOCK_MAX_BUF_SIZE)
+		vsk->buffer_size = VIRTIO_VSOCK_MAX_BUF_SIZE;
+
+	vvs->buf_alloc = vsk->buffer_size;
+
+	spin_lock_init(&vvs->rx_lock);
+	spin_lock_init(&vvs->tx_lock);
+	skb_queue_head_init(&vvs->rx_queue);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_do_socket_init);
+
+/* sk_lock held by the caller */
+void virtio_transport_notify_buffer_size(struct vsock_sock *vsk, u64 *val)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	if (*val > VIRTIO_VSOCK_MAX_BUF_SIZE)
+		*val = VIRTIO_VSOCK_MAX_BUF_SIZE;
+
+	vvs->buf_alloc = *val;
+
+	virtio_transport_send_credit_update(vsk);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_buffer_size);
+
+int
+virtio_transport_notify_poll_in(struct vsock_sock *vsk,
+				size_t target,
+				bool *data_ready_now)
+{
+	*data_ready_now = vsock_stream_has_data(vsk) >= target;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_poll_in);
+
+int
+virtio_transport_notify_poll_out(struct vsock_sock *vsk,
+				 size_t target,
+				 bool *space_avail_now)
+{
+	s64 free_space;
+
+	free_space = vsock_stream_has_space(vsk);
+	if (free_space > 0)
+		*space_avail_now = true;
+	else if (free_space == 0)
+		*space_avail_now = false;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_poll_out);
+
+int virtio_transport_notify_recv_init(struct vsock_sock *vsk,
+	size_t target, struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_init);
+
+int virtio_transport_notify_recv_pre_block(struct vsock_sock *vsk,
+	size_t target, struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_pre_block);
+
+int virtio_transport_notify_recv_pre_dequeue(struct vsock_sock *vsk,
+	size_t target, struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_pre_dequeue);
+
+int virtio_transport_notify_recv_post_dequeue(struct vsock_sock *vsk,
+	size_t target, ssize_t copied, bool data_read,
+	struct vsock_transport_recv_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_post_dequeue);
+
+int virtio_transport_notify_send_init(struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_init);
+
+int virtio_transport_notify_send_pre_block(struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_pre_block);
+
+int virtio_transport_notify_send_pre_enqueue(struct vsock_sock *vsk,
+	struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_pre_enqueue);
+
+int virtio_transport_notify_send_post_enqueue(struct vsock_sock *vsk,
+	ssize_t written, struct vsock_transport_send_notify_data *data)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_notify_send_post_enqueue);
+
+u64 virtio_transport_stream_rcvhiwat(struct vsock_sock *vsk)
+{
+	return vsk->buffer_size;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_rcvhiwat);
+
+bool virtio_transport_stream_is_active(struct vsock_sock *vsk)
+{
+	return true;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_is_active);
+
+bool virtio_transport_stream_allow(u32 cid, u32 port)
+{
+	return true;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_allow);
+
+int virtio_transport_dgram_bind(struct vsock_sock *vsk,
+				struct sockaddr_vm *addr)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_bind);
+
+bool virtio_transport_dgram_allow(u32 cid, u32 port)
+{
+	return false;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_allow);
+
+int virtio_transport_connect(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_REQUEST,
+		.vsk = vsk,
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_connect);
+
+int virtio_transport_shutdown(struct vsock_sock *vsk, int mode)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_SHUTDOWN,
+		.flags = (mode & RCV_SHUTDOWN ?
+			  VIRTIO_VSOCK_SHUTDOWN_RCV : 0) |
+			 (mode & SEND_SHUTDOWN ?
+			  VIRTIO_VSOCK_SHUTDOWN_SEND : 0),
+		.vsk = vsk,
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_shutdown);
+
+int
+virtio_transport_dgram_enqueue(struct vsock_sock *vsk,
+			       struct sockaddr_vm *remote_addr,
+			       struct msghdr *msg,
+			       size_t dgram_len)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_dgram_enqueue);
+
+ssize_t
+virtio_transport_stream_enqueue(struct vsock_sock *vsk,
+				struct msghdr *msg,
+				size_t len)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RW,
+		.msg = msg,
+		.pkt_len = len,
+		.vsk = vsk,
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_stream_enqueue);
+
+void virtio_transport_destruct(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	kfree(vvs);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_destruct);
+
+static int virtio_transport_reset(struct vsock_sock *vsk,
+				  struct sk_buff *skb)
+{
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RST,
+		.reply = !!skb,
+		.vsk = vsk,
+	};
+
+	/* Send RST only if the original pkt is not a RST pkt */
+	if (skb && le16_to_cpu(virtio_vsock_hdr(skb)->op) == VIRTIO_VSOCK_OP_RST)
+		return 0;
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+
+/* Normally packets are associated with a socket.  There may be no socket if an
+ * 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 sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RST,
+		.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(hdr->op) == VIRTIO_VSOCK_OP_RST)
+		return 0;
+
+	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) {
+		kfree_skb(reply);
+		return -ENOTCONN;
+	}
+
+	return t->send_pkt(reply);
+}
+
+/* This function should be called with sk_lock held and SOCK_DONE set */
+static void virtio_transport_remove_sock(struct vsock_sock *vsk)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+
+	/* We don't need to take rx_lock, as the socket is closing and we are
+	 * removing it.
+	 */
+	__skb_queue_purge(&vvs->rx_queue);
+	vsock_remove_sock(vsk);
+}
+
+static void virtio_transport_wait_close(struct sock *sk, long timeout)
+{
+	if (timeout) {
+		DEFINE_WAIT_FUNC(wait, woken_wake_function);
+
+		add_wait_queue(sk_sleep(sk), &wait);
+
+		do {
+			if (sk_wait_event(sk, &timeout,
+					  sock_flag(sk, SOCK_DONE), &wait))
+				break;
+		} while (!signal_pending(current) && timeout);
+
+		remove_wait_queue(sk_sleep(sk), &wait);
+	}
+}
+
+static void virtio_transport_do_close(struct vsock_sock *vsk,
+				      bool cancel_timeout)
+{
+	struct sock *sk = sk_vsock(vsk);
+
+	sock_set_flag(sk, SOCK_DONE);
+	vsk->peer_shutdown = SHUTDOWN_MASK;
+	if (vsock_stream_has_data(vsk) <= 0)
+		sk->sk_state = TCP_CLOSING;
+	sk->sk_state_change(sk);
+
+	if (vsk->close_work_scheduled &&
+	    (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) {
+		vsk->close_work_scheduled = false;
+
+		virtio_transport_remove_sock(vsk);
+
+		/* Release refcnt obtained when we scheduled the timeout */
+		sock_put(sk);
+	}
+}
+
+static void virtio_transport_close_timeout(struct work_struct *work)
+{
+	struct vsock_sock *vsk =
+		container_of(work, struct vsock_sock, close_work.work);
+	struct sock *sk = sk_vsock(vsk);
+
+	sock_hold(sk);
+	lock_sock(sk);
+
+	if (!sock_flag(sk, SOCK_DONE)) {
+		(void)virtio_transport_reset(vsk, NULL);
+
+		virtio_transport_do_close(vsk, false);
+	}
+
+	vsk->close_work_scheduled = false;
+
+	release_sock(sk);
+	sock_put(sk);
+}
+
+/* User context, vsk->sk is locked */
+static bool virtio_transport_close(struct vsock_sock *vsk)
+{
+	struct sock *sk = &vsk->sk;
+
+	if (!(sk->sk_state == TCP_ESTABLISHED ||
+	      sk->sk_state == TCP_CLOSING))
+		return true;
+
+	/* Already received SHUTDOWN from peer, reply with RST */
+	if ((vsk->peer_shutdown & SHUTDOWN_MASK) == SHUTDOWN_MASK) {
+		(void)virtio_transport_reset(vsk, NULL);
+		return true;
+	}
+
+	if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK)
+		(void)virtio_transport_shutdown(vsk, SHUTDOWN_MASK);
+
+	if (sock_flag(sk, SOCK_LINGER) && !(current->flags & PF_EXITING))
+		virtio_transport_wait_close(sk, sk->sk_lingertime);
+
+	if (sock_flag(sk, SOCK_DONE)) {
+		return true;
+	}
+
+	sock_hold(sk);
+	INIT_DELAYED_WORK(&vsk->close_work,
+			  virtio_transport_close_timeout);
+	vsk->close_work_scheduled = true;
+	schedule_delayed_work(&vsk->close_work, VSOCK_CLOSE_TIMEOUT);
+	return false;
+}
+
+void virtio_transport_release(struct vsock_sock *vsk)
+{
+	struct sock *sk = &vsk->sk;
+	bool remove_sock = true;
+
+	if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)
+		remove_sock = virtio_transport_close(vsk);
+
+	if (remove_sock) {
+		sock_set_flag(sk, SOCK_DONE);
+		virtio_transport_remove_sock(vsk);
+	}
+}
+EXPORT_SYMBOL_GPL(virtio_transport_release);
+
+static int
+virtio_transport_recv_connecting(struct sock *sk,
+				 struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	int skerr;
+	int err;
+
+	switch (le16_to_cpu(hdr->op)) {
+	case VIRTIO_VSOCK_OP_RESPONSE:
+		sk->sk_state = TCP_ESTABLISHED;
+		sk->sk_socket->state = SS_CONNECTED;
+		vsock_insert_connected(vsk);
+		sk->sk_state_change(sk);
+		break;
+	case VIRTIO_VSOCK_OP_INVALID:
+		break;
+	case VIRTIO_VSOCK_OP_RST:
+		skerr = ECONNRESET;
+		err = 0;
+		goto destroy;
+	default:
+		skerr = EPROTO;
+		err = -EINVAL;
+		goto destroy;
+	}
+	return 0;
+
+destroy:
+	virtio_transport_reset(vsk, skb);
+	sk->sk_state = TCP_CLOSE;
+	sk->sk_err = skerr;
+	sk_error_report(sk);
+	return err;
+}
+
+static void
+virtio_transport_recv_enqueue(struct vsock_sock *vsk,
+			      struct sk_buff *skb)
+{
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	bool can_enqueue, free_pkt = false;
+	struct virtio_vsock_hdr *hdr;
+	u32 len;
+
+	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, len);
+	if (!can_enqueue) {
+		free_pkt = true;
+		goto out;
+	}
+
+	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 (len <= GOOD_COPY_LEN && !skb_queue_empty(&vvs->rx_queue)) {
+		struct virtio_vsock_hdr *last_hdr;
+		struct sk_buff *last_skb;
+
+		last_skb = skb_peek_tail(&vvs->rx_queue);
+		last_hdr = virtio_vsock_hdr(last_skb);
+
+		/* If there is space in the last packet queued, we copy the
+		 * new packet in its buffer. We avoid this if the last packet
+		 * queued has VIRTIO_VSOCK_SEQ_EOM set, because this is
+		 * delimiter of SEQPACKET message, so 'pkt' is the first packet
+		 * of a new message.
+		 */
+		if (skb->len < skb_tailroom(last_skb) &&
+		    !(le32_to_cpu(last_hdr->flags) & VIRTIO_VSOCK_SEQ_EOM)) {
+			memcpy(skb_put(last_skb, skb->len), skb->data, skb->len);
+			free_pkt = true;
+			last_hdr->flags |= hdr->flags;
+			le32_add_cpu(&last_hdr->len, len);
+			goto out;
+		}
+	}
+
+	__skb_queue_tail(&vvs->rx_queue, skb);
+
+out:
+	spin_unlock_bh(&vvs->rx_lock);
+	if (free_pkt)
+		kfree_skb(skb);
+}
+
+static int
+virtio_transport_recv_connected(struct sock *sk,
+				struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	int err = 0;
+
+	switch (le16_to_cpu(hdr->op)) {
+	case VIRTIO_VSOCK_OP_RW:
+		virtio_transport_recv_enqueue(vsk, skb);
+		vsock_data_ready(sk);
+		return err;
+	case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
+		virtio_transport_send_credit_update(vsk);
+		break;
+	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
+		sk->sk_write_space(sk);
+		break;
+	case VIRTIO_VSOCK_OP_SHUTDOWN:
+		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SHUTDOWN_RCV)
+			vsk->peer_shutdown |= RCV_SHUTDOWN;
+		if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SHUTDOWN_SEND)
+			vsk->peer_shutdown |= SEND_SHUTDOWN;
+		if (vsk->peer_shutdown == SHUTDOWN_MASK) {
+			if (vsock_stream_has_data(vsk) <= 0 && !sock_flag(sk, SOCK_DONE)) {
+				(void)virtio_transport_reset(vsk, NULL);
+				virtio_transport_do_close(vsk, true);
+			}
+			/* Remove this socket anyway because the remote peer sent
+			 * the shutdown. This way a new connection will succeed
+			 * if the remote peer uses the same source port,
+			 * even if the old socket is still unreleased, but now disconnected.
+			 */
+			vsock_remove_sock(vsk);
+		}
+		if (le32_to_cpu(virtio_vsock_hdr(skb)->flags))
+			sk->sk_state_change(sk);
+		break;
+	case VIRTIO_VSOCK_OP_RST:
+		virtio_transport_do_close(vsk, true);
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+	kfree_skb(skb);
+	return err;
+}
+
+static void
+virtio_transport_recv_disconnecting(struct sock *sk,
+				    struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	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 sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct virtio_vsock_pkt_info info = {
+		.op = VIRTIO_VSOCK_OP_RESPONSE,
+		.remote_cid = le64_to_cpu(hdr->src_cid),
+		.remote_port = le32_to_cpu(hdr->src_port),
+		.reply = true,
+		.vsk = vsk,
+	};
+
+	return virtio_transport_send_pkt_info(vsk, &info);
+}
+
+static bool virtio_transport_space_update(struct sock *sk,
+					  struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	struct virtio_vsock_sock *vvs = vsk->trans;
+	bool space_available;
+
+	/* Listener sockets are not associated with any transport, so we are
+	 * not able to take the state to see if there is space available in the
+	 * remote peer, but since they are only used to receive requests, we
+	 * can assume that there is always space available in the other peer.
+	 */
+	if (!vvs)
+		return true;
+
+	/* buf_alloc and fwd_cnt is always included in the hdr */
+	spin_lock_bh(&vvs->tx_lock);
+	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;
+}
+
+/* Handle server socket */
+static int
+virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
+			     struct virtio_transport *t)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	struct vsock_sock *vchild;
+	struct sock *child;
+	int ret;
+
+	if (le16_to_cpu(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, skb);
+		return -ENOMEM;
+	}
+
+	child = vsock_create_connected(sk);
+	if (!child) {
+		virtio_transport_reset_no_sock(t, skb);
+		return -ENOMEM;
+	}
+
+	sk_acceptq_added(sk);
+
+	lock_sock_nested(child, SINGLE_DEPTH_NESTING);
+
+	child->sk_state = TCP_ESTABLISHED;
+
+	vchild = vsock_sk(child);
+	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
+	 * where we received the request.
+	 */
+	if (ret || vchild->transport != &t->transport) {
+		release_sock(child);
+		virtio_transport_reset_no_sock(t, skb);
+		sock_put(child);
+		return ret;
+	}
+
+	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, skb);
+
+	release_sock(child);
+
+	sk->sk_data_ready(sk);
+	return 0;
+}
+
+static bool virtio_transport_valid_type(u16 type)
+{
+	return (type == VIRTIO_VSOCK_TYPE_STREAM) ||
+	       (type == VIRTIO_VSOCK_TYPE_SEQPACKET);
+}
+
+/* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex
+ * lock.
+ */
+void virtio_transport_recv_pkt(struct virtio_transport *t,
+			       struct sk_buff *skb)
+{
+	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
+	struct sockaddr_vm src, dst;
+	struct vsock_sock *vsk;
+	struct sock *sk;
+	bool space_available;
+
+	vsock_addr_init(&src, le64_to_cpu(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(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;
+	}
+
+	/* The socket must be in connected or bound table
+	 * otherwise send reset back
+	 */
+	sk = vsock_find_connected_socket(&src, &dst);
+	if (!sk) {
+		sk = vsock_find_bound_socket(&dst);
+		if (!sk) {
+			(void)virtio_transport_reset_no_sock(t, skb);
+			goto free_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;
+	}
+
+	if (!skb_set_owner_sk_safe(skb, sk)) {
+		WARN_ONCE(1, "receiving vsock socket has sk_refcnt == 0\n");
+		goto free_pkt;
+	}
+
+	vsk = vsock_sk(sk);
+
+	lock_sock(sk);
+
+	/* Check if sk has been closed before lock_sock */
+	if (sock_flag(sk, SOCK_DONE)) {
+		(void)virtio_transport_reset_no_sock(t, skb);
+		release_sock(sk);
+		sock_put(sk);
+		goto free_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)
+		vsk->local_addr.svm_cid = dst.svm_cid;
+
+	if (space_available)
+		sk->sk_write_space(sk);
+
+	switch (sk->sk_state) {
+	case TCP_LISTEN:
+		virtio_transport_recv_listen(sk, skb, t);
+		kfree_skb(skb);
+		break;
+	case TCP_SYN_SENT:
+		virtio_transport_recv_connecting(sk, skb);
+		kfree_skb(skb);
+		break;
+	case TCP_ESTABLISHED:
+		virtio_transport_recv_connected(sk, skb);
+		break;
+	case TCP_CLOSING:
+		virtio_transport_recv_disconnecting(sk, skb);
+		kfree_skb(skb);
+		break;
+	default:
+		(void)virtio_transport_reset_no_sock(t, skb);
+		kfree_skb(skb);
+		break;
+	}
+
+	release_sock(sk);
+
+	/* Release refcnt obtained when we fetched this socket out of the
+	 * bound or connected list.
+	 */
+	sock_put(sk);
+	return;
+
+free_pkt:
+	kfree_skb(skb);
+}
+EXPORT_SYMBOL_GPL(virtio_transport_recv_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)
+{
+	struct sk_buff_head freeme;
+	struct sk_buff *skb, *tmp;
+	int cnt = 0;
+
+	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 (virtio_vsock_skb_reply(skb))
+			cnt++;
+	}
+	spin_unlock_bh(&queue->lock);
+
+	__skb_queue_purge(&freeme);
+
+	return cnt;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_purge_skbs);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Asias He");
+MODULE_DESCRIPTION("common code for virtio vsock");