Commit message: vhost-net: fix use-after-free in vhost_net_flush

vhost_net_ubuf_put_and_wait has a confusing name:
it will actually also free it's argument.
Thus since commit 1280c27f8e29acf4af2da914e80ec27c3dbd5c01
    "vhost-net: flush outstanding DMAs on memory change"
vhost_net_flush tries to use the argument after passing it
to vhost_net_ubuf_put_and_wait, this results
in use after free.
To fix, don't free the argument in vhost_net_ubuf_put_and_wait,
add an new API for callers that want to free ubufs.

Acked-by: Asias He <asias@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2013-4127
CWE: CWE-399
Vulnerability description: Use-after-free vulnerability in the vhost_net_set_backend function in drivers/vhost/net.c in the Linux kernel through 3.10.3 allows local users to cause a denial of service (OOPS and system crash) via vectors involving powering on a virtual machine.

Project: linux
File: net.c

static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
			   size_t len, int iovcount)
{
	int seg = 0;
	size_t size;

	while (len && seg < iovcount) {
		size = min(from->iov_len, len);
		to->iov_base = from->iov_base;
		to->iov_len = size;
		len -= size;
		++from;
		++to;
		++seg;
	}
}

Project: linux
File: net.c

static struct socket *get_raw_socket(int fd)
{
	struct {
		struct sockaddr_ll sa;
		char  buf[MAX_ADDR_LEN];
	} uaddr;
	int uaddr_len = sizeof uaddr, r;
	struct socket *sock = sockfd_lookup(fd, &r);

	if (!sock)
		return ERR_PTR(-ENOTSOCK);

	/* Parameter checking */
	if (sock->sk->sk_type != SOCK_RAW) {
		r = -ESOCKTNOSUPPORT;
		goto err;
	}

	r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
			       &uaddr_len, 0);
	if (r)
		goto err;

	if (uaddr.sa.sll_family != AF_PACKET) {
		r = -EPFNOSUPPORT;
		goto err;
	}
	return sock;
err:
	fput(sock->file);
	return ERR_PTR(r);
}

Project: linux
File: net.c

static struct socket *get_socket(int fd)
{
	struct socket *sock;

	/* special case to disable backend */
	if (fd == -1)
		return NULL;
	sock = get_raw_socket(fd);
	if (!IS_ERR(sock))
		return sock;
	sock = get_tap_socket(fd);
	if (!IS_ERR(sock))
		return sock;
	return ERR_PTR(-ENOTSOCK);
}

Project: linux
File: net.c

static struct socket *get_tap_socket(int fd)
{
	struct file *file = fget(fd);
	struct socket *sock;

	if (!file)
		return ERR_PTR(-EBADF);
	sock = tun_get_socket(file);
	if (!IS_ERR(sock))
		return sock;
	sock = macvtap_get_socket(file);
	if (IS_ERR(sock))
		fput(file);
	return sock;
}

Project: linux
File: net.c

static void handle_rx(struct vhost_net *net)
{
	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
	struct vhost_virtqueue *vq = &nvq->vq;
	unsigned uninitialized_var(in), log;
	struct vhost_log *vq_log;
	struct msghdr msg = {
		.msg_name = NULL,
		.msg_namelen = 0,
		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
		.msg_controllen = 0,
		.msg_iov = vq->iov,
		.msg_flags = MSG_DONTWAIT,
	};
	struct virtio_net_hdr_mrg_rxbuf hdr = {
		.hdr.flags = 0,
		.hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
	};
	size_t total_len = 0;
	int err, mergeable;
	s16 headcount;
	size_t vhost_hlen, sock_hlen;
	size_t vhost_len, sock_len;
	/* TODO: check that we are running from vhost_worker? */
	struct socket *sock = rcu_dereference_check(vq->private_data, 1);

	if (!sock)
		return;

	mutex_lock(&vq->mutex);
	vhost_disable_notify(&net->dev, vq);
	vhost_hlen = nvq->vhost_hlen;
	sock_hlen = nvq->sock_hlen;

	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
		vq->log : NULL;
	mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);

	while ((sock_len = peek_head_len(sock->sk))) {
		sock_len += sock_hlen;
		vhost_len = sock_len + vhost_hlen;
		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
					&in, vq_log, &log,
					likely(mergeable) ? UIO_MAXIOV : 1);
		/* On error, stop handling until the next kick. */
		if (unlikely(headcount < 0))
			break;
		/* OK, now we need to know about added descriptors. */
		if (!headcount) {
			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
				/* They have slipped one in as we were
				 * doing that: check again. */
				vhost_disable_notify(&net->dev, vq);
				continue;
			}
			/* Nothing new?  Wait for eventfd to tell us
			 * they refilled. */
			break;
		}
		/* We don't need to be notified again. */
		if (unlikely((vhost_hlen)))
			/* Skip header. TODO: support TSO. */
			move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
		else
			/* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
			 * needed because recvmsg can modify msg_iov. */
			copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
		msg.msg_iovlen = in;
		err = sock->ops->recvmsg(NULL, sock, &msg,
					 sock_len, MSG_DONTWAIT | MSG_TRUNC);
		/* Userspace might have consumed the packet meanwhile:
		 * it's not supposed to do this usually, but might be hard
		 * to prevent. Discard data we got (if any) and keep going. */
		if (unlikely(err != sock_len)) {
			pr_debug("Discarded rx packet: "
				 " len %d, expected %zd\n", err, sock_len);
			vhost_discard_vq_desc(vq, headcount);
			continue;
		}
		if (unlikely(vhost_hlen) &&
		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
				      vhost_hlen)) {
			vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
			       vq->iov->iov_base);
			break;
		}
		/* TODO: Should check and handle checksum. */
		if (likely(mergeable) &&
		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
				      offsetof(typeof(hdr), num_buffers),
				      sizeof hdr.num_buffers)) {
			vq_err(vq, "Failed num_buffers write");
			vhost_discard_vq_desc(vq, headcount);
			break;
		}
		vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
					    headcount);
		if (unlikely(vq_log))
			vhost_log_write(vq, vq_log, log, vhost_len);
		total_len += vhost_len;
		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
			vhost_poll_queue(&vq->poll);
			break;
		}
	}

	mutex_unlock(&vq->mutex);
}

Project: linux
File: net.c

static void handle_rx_kick(struct vhost_work *work)
{
	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
						  poll.work);
	struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);

	handle_rx(net);
}

Project: linux
File: net.c

static void handle_rx_net(struct vhost_work *work)
{
	struct vhost_net *net = container_of(work, struct vhost_net,
					     poll[VHOST_NET_VQ_RX].work);
	handle_rx(net);
}

Project: linux
File: net.c

static void handle_tx(struct vhost_net *net)
{
	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
	struct vhost_virtqueue *vq = &nvq->vq;
	unsigned out, in, s;
	int head;
	struct msghdr msg = {
		.msg_name = NULL,
		.msg_namelen = 0,
		.msg_control = NULL,
		.msg_controllen = 0,
		.msg_iov = vq->iov,
		.msg_flags = MSG_DONTWAIT,
	};
	size_t len, total_len = 0;
	int err;
	size_t hdr_size;
	struct socket *sock;
	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
	bool zcopy, zcopy_used;

	/* TODO: check that we are running from vhost_worker? */
	sock = rcu_dereference_check(vq->private_data, 1);
	if (!sock)
		return;

	mutex_lock(&vq->mutex);
	vhost_disable_notify(&net->dev, vq);

	hdr_size = nvq->vhost_hlen;
	zcopy = nvq->ubufs;

	for (;;) {
		/* Release DMAs done buffers first */
		if (zcopy)
			vhost_zerocopy_signal_used(net, vq);

		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
					 ARRAY_SIZE(vq->iov),
					 &out, &in,
					 NULL, NULL);
		/* On error, stop handling until the next kick. */
		if (unlikely(head < 0))
			break;
		/* Nothing new?  Wait for eventfd to tell us they refilled. */
		if (head == vq->num) {
			int num_pends;

			/* If more outstanding DMAs, queue the work.
			 * Handle upend_idx wrap around
			 */
			num_pends = likely(nvq->upend_idx >= nvq->done_idx) ?
				    (nvq->upend_idx - nvq->done_idx) :
				    (nvq->upend_idx + UIO_MAXIOV -
				     nvq->done_idx);
			if (unlikely(num_pends > VHOST_MAX_PEND))
				break;
			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
				vhost_disable_notify(&net->dev, vq);
				continue;
			}
			break;
		}
		if (in) {
			vq_err(vq, "Unexpected descriptor format for TX: "
			       "out %d, int %d\n", out, in);
			break;
		}
		/* Skip header. TODO: support TSO. */
		s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
		msg.msg_iovlen = out;
		len = iov_length(vq->iov, out);
		/* Sanity check */
		if (!len) {
			vq_err(vq, "Unexpected header len for TX: "
			       "%zd expected %zd\n",
			       iov_length(nvq->hdr, s), hdr_size);
			break;
		}
		zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN ||
				       nvq->upend_idx != nvq->done_idx);

		/* use msg_control to pass vhost zerocopy ubuf info to skb */
		if (zcopy_used) {
			vq->heads[nvq->upend_idx].id = head;
			if (!vhost_net_tx_select_zcopy(net) ||
			    len < VHOST_GOODCOPY_LEN) {
				/* copy don't need to wait for DMA done */
				vq->heads[nvq->upend_idx].len =
							VHOST_DMA_DONE_LEN;
				msg.msg_control = NULL;
				msg.msg_controllen = 0;
				ubufs = NULL;
			} else {
				struct ubuf_info *ubuf;
				ubuf = nvq->ubuf_info + nvq->upend_idx;

				vq->heads[nvq->upend_idx].len =
					VHOST_DMA_IN_PROGRESS;
				ubuf->callback = vhost_zerocopy_callback;
				ubuf->ctx = nvq->ubufs;
				ubuf->desc = nvq->upend_idx;
				msg.msg_control = ubuf;
				msg.msg_controllen = sizeof(ubuf);
				ubufs = nvq->ubufs;
				kref_get(&ubufs->kref);
			}
			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
		} else
			msg.msg_control = NULL;
		/* TODO: Check specific error and bomb out unless ENOBUFS? */
		err = sock->ops->sendmsg(NULL, sock, &msg, len);
		if (unlikely(err < 0)) {
			if (zcopy_used) {
				if (ubufs)
					vhost_net_ubuf_put(ubufs);
				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
					% UIO_MAXIOV;
			}
			vhost_discard_vq_desc(vq, 1);
			break;
		}
		if (err != len)
			pr_debug("Truncated TX packet: "
				 " len %d != %zd\n", err, len);
		if (!zcopy_used)
			vhost_add_used_and_signal(&net->dev, vq, head, 0);
		else
			vhost_zerocopy_signal_used(net, vq);
		total_len += len;
		vhost_net_tx_packet(net);
		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
			vhost_poll_queue(&vq->poll);
			break;
		}
	}

	mutex_unlock(&vq->mutex);
}

Project: linux
File: net.c

static void handle_tx_net(struct vhost_work *work)
{
	struct vhost_net *net = container_of(work, struct vhost_net,
					     poll[VHOST_NET_VQ_TX].work);
	handle_tx(net);
}

Project: linux
File: net.c

static int move_iovec_hdr(struct iovec *from, struct iovec *to,
			  size_t len, int iov_count)
{
	int seg = 0;
	size_t size;

	while (len && seg < iov_count) {
		size = min(from->iov_len, len);
		to->iov_base = from->iov_base;
		to->iov_len = size;
		from->iov_len -= size;
		from->iov_base += size;
		len -= size;
		++from;
		++to;
		++seg;
	}
	return seg;
}

Project: linux
File: net.c

static int peek_head_len(struct sock *sk)
{
	struct sk_buff *head;
	int len = 0;
	unsigned long flags;

	spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
	head = skb_peek(&sk->sk_receive_queue);
	if (likely(head)) {
		len = head->len;
		if (vlan_tx_tag_present(head))
			len += VLAN_HLEN;
	}

	spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
	return len;
}

Project: linux
File: net.c

static void vhost_net_clear_ubuf_info(struct vhost_net *n)
{
	int i;

	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
		kfree(n->vqs[i].ubuf_info);
		n->vqs[i].ubuf_info = NULL;
	}
}

Project: linux
File: net.c

static void vhost_net_disable_vq(struct vhost_net *n,
				 struct vhost_virtqueue *vq)
{
	struct vhost_net_virtqueue *nvq =
		container_of(vq, struct vhost_net_virtqueue, vq);
	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
	if (!vq->private_data)
		return;
	vhost_poll_stop(poll);
}

Project: linux
File: net.c

static int vhost_net_enable_vq(struct vhost_net *n,
				struct vhost_virtqueue *vq)
{
	struct vhost_net_virtqueue *nvq =
		container_of(vq, struct vhost_net_virtqueue, vq);
	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
	struct socket *sock;

	sock = rcu_dereference_protected(vq->private_data,
					 lockdep_is_held(&vq->mutex));
	if (!sock)
		return 0;

	return vhost_poll_start(poll, sock->file);
}

Project: linux
File: net.c

static void vhost_net_enable_zcopy(int vq)
{
	vhost_net_zcopy_mask |= 0x1 << vq;
}

Project: linux
File: net.c

static void vhost_net_exit(void)
{
	misc_deregister(&vhost_net_misc);
}

Project: linux
File: net.c

static void vhost_net_flush(struct vhost_net *n)
{
	vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
	vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
	if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
		n->tx_flush = true;
		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
		/* Wait for all lower device DMAs done. */
		vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
		n->tx_flush = false;
		kref_init(&n->vqs[VHOST_NET_VQ_TX].ubufs->kref);
		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
	}
}

Project: linux
File: net.c

static void vhost_net_flush_vq(struct vhost_net *n, int index)
{
	vhost_poll_flush(n->poll + index);
	vhost_poll_flush(&n->vqs[index].vq.poll);
}

Project: linux
File: net.c

static int vhost_net_init(void)
{
	if (experimental_zcopytx)
		vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
	return misc_register(&vhost_net_misc);
}

Project: linux
File: net.c

static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
			    unsigned long arg)
{
	struct vhost_net *n = f->private_data;
	void __user *argp = (void __user *)arg;
	u64 __user *featurep = argp;
	struct vhost_vring_file backend;
	u64 features;
	int r;

	switch (ioctl) {
	case VHOST_NET_SET_BACKEND:
		if (copy_from_user(&backend, argp, sizeof backend))
			return -EFAULT;
		return vhost_net_set_backend(n, backend.index, backend.fd);
	case VHOST_GET_FEATURES:
		features = VHOST_NET_FEATURES;
		if (copy_to_user(featurep, &features, sizeof features))
			return -EFAULT;
		return 0;
	case VHOST_SET_FEATURES:
		if (copy_from_user(&features, featurep, sizeof features))
			return -EFAULT;
		if (features & ~VHOST_NET_FEATURES)
			return -EOPNOTSUPP;
		return vhost_net_set_features(n, features);
	case VHOST_RESET_OWNER:
		return vhost_net_reset_owner(n);
	case VHOST_SET_OWNER:
		return vhost_net_set_owner(n);
	default:
		mutex_lock(&n->dev.mutex);
		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
		if (r == -ENOIOCTLCMD)
			r = vhost_vring_ioctl(&n->dev, ioctl, argp);
		else
			vhost_net_flush(n);
		mutex_unlock(&n->dev.mutex);
		return r;
	}
}

Project: linux
File: net.c

static int vhost_net_open(struct inode *inode, struct file *f)
{
	struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
	struct vhost_dev *dev;
	struct vhost_virtqueue **vqs;
	int r, i;

	if (!n)
		return -ENOMEM;
	vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
	if (!vqs) {
		kfree(n);
		return -ENOMEM;
	}

	dev = &n->dev;
	vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
	vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
	n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
	n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
		n->vqs[i].ubufs = NULL;
		n->vqs[i].ubuf_info = NULL;
		n->vqs[i].upend_idx = 0;
		n->vqs[i].done_idx = 0;
		n->vqs[i].vhost_hlen = 0;
		n->vqs[i].sock_hlen = 0;
	}
	r = vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
	if (r < 0) {
		kfree(n);
		kfree(vqs);
		return r;
	}

	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);

	f->private_data = n;

	return 0;
}

Project: linux
File: net.c

static int vhost_net_release(struct inode *inode, struct file *f)
{
	struct vhost_net *n = f->private_data;
	struct socket *tx_sock;
	struct socket *rx_sock;

	vhost_net_stop(n, &tx_sock, &rx_sock);
	vhost_net_flush(n);
	vhost_dev_stop(&n->dev);
	vhost_dev_cleanup(&n->dev, false);
	vhost_net_vq_reset(n);
	if (tx_sock)
		fput(tx_sock->file);
	if (rx_sock)
		fput(rx_sock->file);
	/* We do an extra flush before freeing memory,
	 * since jobs can re-queue themselves. */
	vhost_net_flush(n);
	kfree(n->dev.vqs);
	kfree(n);
	return 0;
}

Project: linux
File: net.c

static long vhost_net_reset_owner(struct vhost_net *n)
{
	struct socket *tx_sock = NULL;
	struct socket *rx_sock = NULL;
	long err;
	struct vhost_memory *memory;

	mutex_lock(&n->dev.mutex);
	err = vhost_dev_check_owner(&n->dev);
	if (err)
		goto done;
	memory = vhost_dev_reset_owner_prepare();
	if (!memory) {
		err = -ENOMEM;
		goto done;
	}
	vhost_net_stop(n, &tx_sock, &rx_sock);
	vhost_net_flush(n);
	vhost_dev_reset_owner(&n->dev, memory);
	vhost_net_vq_reset(n);
done:
	mutex_unlock(&n->dev.mutex);
	if (tx_sock)
		fput(tx_sock->file);
	if (rx_sock)
		fput(rx_sock->file);
	return err;
}

Project: linux
File: net.c

static int vhost_net_set_features(struct vhost_net *n, u64 features)
{
	size_t vhost_hlen, sock_hlen, hdr_len;
	int i;

	hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
			sizeof(struct virtio_net_hdr_mrg_rxbuf) :
			sizeof(struct virtio_net_hdr);
	if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
		/* vhost provides vnet_hdr */
		vhost_hlen = hdr_len;
		sock_hlen = 0;
	} else {
		/* socket provides vnet_hdr */
		vhost_hlen = 0;
		sock_hlen = hdr_len;
	}
	mutex_lock(&n->dev.mutex);
	if ((features & (1 << VHOST_F_LOG_ALL)) &&
	    !vhost_log_access_ok(&n->dev)) {
		mutex_unlock(&n->dev.mutex);
		return -EFAULT;
	}
	n->dev.acked_features = features;
	smp_wmb();
	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
		mutex_lock(&n->vqs[i].vq.mutex);
		n->vqs[i].vhost_hlen = vhost_hlen;
		n->vqs[i].sock_hlen = sock_hlen;
		mutex_unlock(&n->vqs[i].vq.mutex);
	}
	vhost_net_flush(n);
	mutex_unlock(&n->dev.mutex);
	return 0;
}

Project: linux
File: net.c

static long vhost_net_set_owner(struct vhost_net *n)
{
	int r;

	mutex_lock(&n->dev.mutex);
	if (vhost_dev_has_owner(&n->dev)) {
		r = -EBUSY;
		goto out;
	}
	r = vhost_net_set_ubuf_info(n);
	if (r)
		goto out;
	r = vhost_dev_set_owner(&n->dev);
	if (r)
		vhost_net_clear_ubuf_info(n);
	vhost_net_flush(n);
out:
	mutex_unlock(&n->dev.mutex);
	return r;
}

Project: linux
File: net.c

int vhost_net_set_ubuf_info(struct vhost_net *n)
{
	bool zcopy;
	int i;

	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
		zcopy = vhost_net_zcopy_mask & (0x1 << i);
		if (!zcopy)
			continue;
		n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
					      UIO_MAXIOV, GFP_KERNEL);
		if  (!n->vqs[i].ubuf_info)
			goto err;
	}
	return 0;

err:
	vhost_net_clear_ubuf_info(n);
	return -ENOMEM;
}

Project: linux
File: net.c

static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
			   struct socket **rx_sock)
{
	*tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
	*rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
}

Project: linux
File: net.c

static void vhost_net_tx_packet(struct vhost_net *net)
{
	++net->tx_packets;
	if (net->tx_packets < 1024)
		return;
	net->tx_packets = 0;
	net->tx_zcopy_err = 0;
}

Project: linux
File: net.c

static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
{
	/* TX flush waits for outstanding DMAs to be done.
	 * Don't start new DMAs.
	 */
	return !net->tx_flush &&
		net->tx_packets / 64 >= net->tx_zcopy_err;
}

Project: linux
File: net.c

vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
{
	struct vhost_net_ubuf_ref *ubufs;
	/* No zero copy backend? Nothing to count. */
	if (!zcopy)
		return NULL;
	ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
	if (!ubufs)
		return ERR_PTR(-ENOMEM);
	kref_init(&ubufs->kref);
	init_waitqueue_head(&ubufs->wait);
	ubufs->vq = vq;
	return ubufs;
}

Project: linux
File: net.c

static void vhost_net_zerocopy_done_signal(struct kref *kref)
{
	struct vhost_net_ubuf_ref *ubufs;

	ubufs = container_of(kref, struct vhost_net_ubuf_ref, kref);
	wake_up(&ubufs->wait);
}

Project: linux
File: net.c

static bool vhost_sock_zcopy(struct socket *sock)
{
	return unlikely(experimental_zcopytx) &&
		sock_flag(sock->sk, SOCK_ZEROCOPY);
}

Project: linux
File: net.c

static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
{
	struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
	struct vhost_virtqueue *vq = ubufs->vq;
	int cnt = atomic_read(&ubufs->kref.refcount);

	/*
	 * Trigger polling thread if guest stopped submitting new buffers:
	 * in this case, the refcount after decrement will eventually reach 1
	 * so here it is 2.
	 * We also trigger polling periodically after each 16 packets
	 * (the value 16 here is more or less arbitrary, it's tuned to trigger
	 * less than 10% of times).
	 */
	if (cnt <= 2 || !(cnt % 16))
		vhost_poll_queue(&vq->poll);
	/* set len to mark this desc buffers done DMA */
	vq->heads[ubuf->desc].len = success ?
		VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
	vhost_net_ubuf_put(ubufs);
}

Project: linux
File: net.c

static int vhost_zerocopy_signal_used(struct vhost_net *net,
				      struct vhost_virtqueue *vq)
{
	struct vhost_net_virtqueue *nvq =
		container_of(vq, struct vhost_net_virtqueue, vq);
	int i;
	int j = 0;

	for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
		if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
			vhost_net_tx_err(net);
		if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
			vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
			vhost_add_used_and_signal(vq->dev, vq,
						  vq->heads[i].id, 0);
			++j;
		} else
			break;
	}
	if (j)
		nvq->done_idx = i;
	return j;
}