Re: [RFC][PATCH v3 2/3] Provides multiple submits and asynchronousnotifications.
From: Michael S. Tsirkin
Date: Thu Apr 22 2010 - 05:54:33 EST
On Thu, Apr 22, 2010 at 04:37:16PM +0800, xiaohui.xin@xxxxxxxxx wrote:
> From: Xin Xiaohui <xiaohui.xin@xxxxxxxxx>
>
> The vhost-net backend now only supports synchronous send/recv
> operations. The patch provides multiple submits and asynchronous
> notifications. This is needed for zero-copy case.
>
> Signed-off-by: Xin Xiaohui <xiaohui.xin@xxxxxxxxx>
> ---
>
> Michael,
>
> >Can't vhost supply a kiocb completion callback that will handle the list?
>
> Yes, thanks. And with it I also remove the vq->receiver finally.
>
> Thanks
> Xiaohui
Nice progress. I commented on some minor issues below.
Thanks!
> drivers/vhost/net.c | 227 +++++++++++++++++++++++++++++++++++++++++++++++--
> drivers/vhost/vhost.c | 115 ++++++++++++++-----------
> drivers/vhost/vhost.h | 14 +++
> 3 files changed, 301 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 22d5fef..4a70f66 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -17,11 +17,13 @@
> #include <linux/workqueue.h>
> #include <linux/rcupdate.h>
> #include <linux/file.h>
> +#include <linux/aio.h>
>
> #include <linux/net.h>
> #include <linux/if_packet.h>
> #include <linux/if_arp.h>
> #include <linux/if_tun.h>
> +#include <linux/mpassthru.h>
> #include <net/sock.h>
>
> @@ -47,6 +49,7 @@ struct vhost_net {
> struct vhost_dev dev;
> struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
> struct vhost_poll poll[VHOST_NET_VQ_MAX];
> + struct kmem_cache *cache;
> /* Tells us whether we are polling a socket for TX.
> * We only do this when socket buffer fills up.
> * Protected by tx vq lock. */
> @@ -91,11 +94,132 @@ static void tx_poll_start(struct vhost_net *net, struct socket *sock)
> net->tx_poll_state = VHOST_NET_POLL_STARTED;
> }
>
> +struct kiocb *notify_dequeue(struct vhost_virtqueue *vq)
> +{
> + struct kiocb *iocb = NULL;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&vq->notify_lock, flags);
> + if (!list_empty(&vq->notifier)) {
> + iocb = list_first_entry(&vq->notifier,
> + struct kiocb, ki_list);
> + list_del(&iocb->ki_list);
> + }
> + spin_unlock_irqrestore(&vq->notify_lock, flags);
> + return iocb;
> +}
> +
> +static void handle_iocb(struct kiocb *iocb)
> +{
> + struct vhost_virtqueue *vq = iocb->private;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&vq->notify_lock, flags);
> + list_add_tail(&iocb->ki_list, &vq->notifier);
> + spin_unlock_irqrestore(&vq->notify_lock, flags);
> +}
> +
checkpatch.pl does not complain about the above?
> +static void handle_async_rx_events_notify(struct vhost_net *net,
> + struct vhost_virtqueue *vq,
> + struct socket *sock)
continuation lines should start to the right of (.
> +{
> + struct kiocb *iocb = NULL;
> + struct vhost_log *vq_log = NULL;
> + int rx_total_len = 0;
> + unsigned int head, log, in, out;
> + int size;
> +
> + if (vq->link_state != VHOST_VQ_LINK_ASYNC)
> + return;
> +
> + if (sock->sk->sk_data_ready)
> + sock->sk->sk_data_ready(sock->sk, 0);
> +
> + vq_log = unlikely(vhost_has_feature(
> + &net->dev, VHOST_F_LOG_ALL)) ? vq->log : NULL;
split the above line at ?, continuation being to the left of ( looks
ugly.
> + while ((iocb = notify_dequeue(vq)) != NULL) {
> + vhost_add_used_and_signal(&net->dev, vq,
> + iocb->ki_pos, iocb->ki_nbytes);
> + log = (int)(iocb->ki_user_data >> 32);
how about we always do the recompute step, and not encode
the log bit in ki_user_data?
> + size = iocb->ki_nbytes;
> + head = iocb->ki_pos;
> + rx_total_len += iocb->ki_nbytes;
> +
> + if (iocb->ki_dtor)
> + iocb->ki_dtor(iocb);
> + kmem_cache_free(net->cache, iocb);
> +
> + /* when log is enabled, recomputing the log info is needed,
> + * since these buffers are in async queue, and may not get
> + * the log info before.
> + */
> + if (unlikely(vq_log)) {
> + if (!log)
> + __vhost_get_vq_desc(&net->dev, vq, vq->iov,
> + ARRAY_SIZE(vq->iov),
> + &out, &in, vq_log,
> + &log, head);
> + vhost_log_write(vq, vq_log, log, size);
> + }
> + if (unlikely(rx_total_len >= VHOST_NET_WEIGHT)) {
> + vhost_poll_queue(&vq->poll);
> + break;
> + }
> + }
> +}
> +
> +static void handle_async_tx_events_notify(struct vhost_net *net,
> + struct vhost_virtqueue *vq)
> +{
> + struct kiocb *iocb = NULL;
> + int tx_total_len = 0;
> +
> + if (vq->link_state != VHOST_VQ_LINK_ASYNC)
> + return;
> +
> + while ((iocb = notify_dequeue(vq)) != NULL) {
> + vhost_add_used_and_signal(&net->dev, vq,
> + iocb->ki_pos, 0);
> + tx_total_len += iocb->ki_nbytes;
> +
> + if (iocb->ki_dtor)
> + iocb->ki_dtor(iocb);
> +
> + kmem_cache_free(net->cache, iocb);
> + if (unlikely(tx_total_len >= VHOST_NET_WEIGHT)) {
> + vhost_poll_queue(&vq->poll);
> + break;
> + }
> + }
> +}
> +
> +static struct kiocb *create_iocb(struct vhost_net *net,
> + struct vhost_virtqueue *vq,
> + unsigned head, unsigned log)
> +{
> + struct kiocb *iocb = NULL;
> +
> + if (vq->link_state != VHOST_VQ_LINK_ASYNC)
> + return NULL;
> + iocb = kmem_cache_zalloc(net->cache, GFP_KERNEL);
> + if (!iocb)
> + return NULL;
> + iocb->private = vq;
> + iocb->ki_pos = head;
> + iocb->ki_dtor = handle_iocb;
> + if (vq == &net->dev.vqs[VHOST_NET_VQ_RX]) {
> + iocb->ki_user_data = ((unsigned long)log << 32 | vq->num);
> + iocb->ki_iovec = vq->hdr;
> + }
> + return iocb;
> +}
> +
> /* Expects to be always run from workqueue - which acts as
> * read-size critical section for our kind of RCU. */
> static void handle_tx(struct vhost_net *net)
> {
> struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
> + struct kiocb *iocb = NULL;
do we need to init this?
> unsigned head, out, in, s;
> struct msghdr msg = {
> .msg_name = NULL,
> @@ -124,6 +248,8 @@ static void handle_tx(struct vhost_net *net)
> tx_poll_stop(net);
> hdr_size = vq->hdr_size;
>
> + handle_async_tx_events_notify(net, vq);
> +
> for (;;) {
> head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
> ARRAY_SIZE(vq->iov),
> @@ -151,6 +277,11 @@ static void handle_tx(struct vhost_net *net)
> /* Skip header. TODO: support TSO. */
> s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
> msg.msg_iovlen = out;
> +
> + iocb = create_iocb(net, vq, head, 0);
For sync case, we can save some cycles by using iocb = NULL.
> + if (vq->link_state == VHOST_VQ_LINK_ASYNC && !iocb)
> + break;
> +
> len = iov_length(vq->iov, out);
> /* Sanity check */
> if (!len) {
Generally, I would like to reduce the number of places
where we do if (link_state == XXX) in code.
It should be possible to do this by splitting common code
out into functions.
> @@ -160,12 +291,18 @@ static void handle_tx(struct vhost_net *net)
> break;
> }
> /* TODO: Check specific error and bomb out unless ENOBUFS? */
> - err = sock->ops->sendmsg(NULL, sock, &msg, len);
> + err = sock->ops->sendmsg(iocb, sock, &msg, len);
> if (unlikely(err < 0)) {
> + if (vq->link_state == VHOST_VQ_LINK_ASYNC)
> + kmem_cache_free(net->cache, iocb);
> vhost_discard_vq_desc(vq);
> tx_poll_start(net, sock);
> break;
> }
> +
> + if (vq->link_state == VHOST_VQ_LINK_ASYNC)
> + continue;
> +
> if (err != len)
> pr_err("Truncated TX packet: "
> " len %d != %zd\n", err, len);
> @@ -177,6 +314,8 @@ static void handle_tx(struct vhost_net *net)
> }
> }
>
> + handle_async_tx_events_notify(net, vq);
> +
> mutex_unlock(&vq->mutex);
> unuse_mm(net->dev.mm);
> }
> @@ -186,6 +325,7 @@ static void handle_tx(struct vhost_net *net)
> static void handle_rx(struct vhost_net *net)
> {
> struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
> + struct kiocb *iocb = NULL;
> unsigned head, out, in, log, s;
> struct vhost_log *vq_log;
> struct msghdr msg = {
> @@ -206,7 +346,8 @@ static void handle_rx(struct vhost_net *net)
> int err;
> size_t hdr_size;
> struct socket *sock = rcu_dereference(vq->private_data);
> - if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
> + if (!sock || (skb_queue_empty(&sock->sk->sk_receive_queue) &&
> + vq->link_state == VHOST_VQ_LINK_SYNC))
> return;
>
> use_mm(net->dev.mm);
> @@ -214,9 +355,17 @@ static void handle_rx(struct vhost_net *net)
> vhost_disable_notify(vq);
> hdr_size = vq->hdr_size;
>
> + /* In async cases, when write log is enabled, in case the submitted
> + * buffers did not get log info before the log enabling, so we'd
> + * better recompute the log info when needed. We do this in
> + * handle_async_rx_events_notify().
> + */
> +
> vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
> vq->log : NULL;
>
> + handle_async_rx_events_notify(net, vq, sock);
> +
> for (;;) {
> head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
> ARRAY_SIZE(vq->iov),
> @@ -245,6 +394,11 @@ static void handle_rx(struct vhost_net *net)
> s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
> msg.msg_iovlen = in;
> len = iov_length(vq->iov, in);
> +
> + iocb = create_iocb(net, vq, head, log);
> + if (vq->link_state == VHOST_VQ_LINK_ASYNC && !iocb)
> + break;
> +
> /* Sanity check */
> if (!len) {
> vq_err(vq, "Unexpected header len for RX: "
> @@ -252,13 +406,20 @@ static void handle_rx(struct vhost_net *net)
> iov_length(vq->hdr, s), hdr_size);
> break;
> }
> - err = sock->ops->recvmsg(NULL, sock, &msg,
> +
> + err = sock->ops->recvmsg(iocb, sock, &msg,
> len, MSG_DONTWAIT | MSG_TRUNC);
> /* TODO: Check specific error and bomb out unless EAGAIN? */
> if (err < 0) {
> + if (vq->link_state == VHOST_VQ_LINK_ASYNC)
> + kmem_cache_free(net->cache, iocb);
> vhost_discard_vq_desc(vq);
> break;
> }
> +
> + if (vq->link_state == VHOST_VQ_LINK_ASYNC)
> + continue;
> +
> /* TODO: Should check and handle checksum. */
> if (err > len) {
> pr_err("Discarded truncated rx packet: "
> @@ -284,10 +445,13 @@ static void handle_rx(struct vhost_net *net)
> }
> }
>
> + handle_async_rx_events_notify(net, vq, sock);
> +
> mutex_unlock(&vq->mutex);
> unuse_mm(net->dev.mm);
> }
>
> +
don't do this
> static void handle_tx_kick(struct work_struct *work)
> {
> struct vhost_virtqueue *vq;
> @@ -338,6 +502,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
> vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT);
> vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN);
> n->tx_poll_state = VHOST_NET_POLL_DISABLED;
> + n->cache = NULL;
> return 0;
> }
>
> @@ -398,6 +563,18 @@ static void vhost_net_flush(struct vhost_net *n)
> vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
> }
>
> +static void vhost_async_cleanup(struct vhost_net *n)
> +{
> + /* clean the notifier */
> + struct vhost_virtqueue *vq = &n->dev.vqs[VHOST_NET_VQ_RX];
> + struct kiocb *iocb = NULL;
> + if (n->cache) {
> + while ((iocb = notify_dequeue(vq)) != NULL)
> + kmem_cache_free(n->cache, iocb);
> + kmem_cache_destroy(n->cache);
> + }
> +}
> +
> static int vhost_net_release(struct inode *inode, struct file *f)
> {
> struct vhost_net *n = f->private_data;
> @@ -414,6 +591,7 @@ static int vhost_net_release(struct inode *inode, struct file *f)
> /* We do an extra flush before freeing memory,
> * since jobs can re-queue themselves. */
> vhost_net_flush(n);
> + vhost_async_cleanup(n);
> kfree(n);
> return 0;
> }
> @@ -462,7 +640,19 @@ static struct socket *get_tun_socket(int fd)
> return sock;
> }
>
> -static struct socket *get_socket(int fd)
> +static struct socket *get_mp_socket(int fd)
> +{
> + struct file *file = fget(fd);
> + struct socket *sock;
> + if (!file)
> + return ERR_PTR(-EBADF);
> + sock = mp_get_socket(file);
> + if (IS_ERR(sock))
> + fput(file);
> + return sock;
> +}
> +
> +static struct socket *get_socket(struct vhost_virtqueue *vq, int fd)
> {
> struct socket *sock;
> if (fd == -1)
> @@ -473,9 +663,30 @@ static struct socket *get_socket(int fd)
> sock = get_tun_socket(fd);
> if (!IS_ERR(sock))
> return sock;
> + sock = get_mp_socket(fd);
> + if (!IS_ERR(sock)) {
> + vq->link_state = VHOST_VQ_LINK_ASYNC;
> + return sock;
> + }
> return ERR_PTR(-ENOTSOCK);
> }
>
> +static void vhost_init_link_state(struct vhost_net *n, int index)
> +{
> + struct vhost_virtqueue *vq = n->vqs + index;
> +
> + WARN_ON(!mutex_is_locked(&vq->mutex));
> + if (vq->link_state == VHOST_VQ_LINK_ASYNC) {
> + INIT_LIST_HEAD(&vq->notifier);
> + spin_lock_init(&vq->notify_lock);
> + if (!n->cache) {
> + n->cache = kmem_cache_create("vhost_kiocb",
> + sizeof(struct kiocb), 0,
> + SLAB_HWCACHE_ALIGN, NULL);
> + }
> + }
> +}
> +
> static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
> {
> struct socket *sock, *oldsock;
> @@ -493,12 +704,15 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
> }
> vq = n->vqs + index;
> mutex_lock(&vq->mutex);
> - sock = get_socket(fd);
> + vq->link_state = VHOST_VQ_LINK_SYNC;
> + sock = get_socket(vq, fd);
> if (IS_ERR(sock)) {
> r = PTR_ERR(sock);
> goto err;
> }
>
> + vhost_init_link_state(n, index);
> +
I think we should just teach get_socket to return link_state
in addition to the socket pointer, and pass the returned value to
vhost_init_link_state.
> /* start polling new socket */
> oldsock = vq->private_data;
> if (sock == oldsock)
> @@ -507,8 +721,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
> vhost_net_disable_vq(n, vq);
> rcu_assign_pointer(vq->private_data, sock);
> vhost_net_enable_vq(n, vq);
> - mutex_unlock(&vq->mutex);
> done:
> + mutex_unlock(&vq->mutex);
> mutex_unlock(&n->dev.mutex);
> if (oldsock) {
> vhost_net_flush_vq(n, index);
why the change above? Are you sure it's safe? Need to be careful here:
doing everything under vq and dev mutex is much simpler.
If this change is required, need to review locking carefully
to make sure we are not introducing races.
> @@ -516,6 +730,7 @@ done:
> }
> return r;
> err:
> + mutex_unlock(&vq->mutex);
> mutex_unlock(&n->dev.mutex);
> return r;
> }
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 97233d5..53dab80 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -715,66 +715,21 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
> return 0;
> }
>
> -/* This looks in the virtqueue and for the first available buffer, and converts
> - * it to an iovec for convenient access. Since descriptors consist of some
> - * number of output then some number of input descriptors, it's actually two
> - * iovecs, but we pack them into one and note how many of each there were.
> - *
> - * This function returns the descriptor number found, or vq->num (which
> - * is never a valid descriptor number) if none was found. */
> -unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
> +unsigned __vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
> struct iovec iov[], unsigned int iov_size,
> unsigned int *out_num, unsigned int *in_num,
> - struct vhost_log *log, unsigned int *log_num)
> + struct vhost_log *log, unsigned int *log_num,
> + unsigned int head)
> {
> struct vring_desc desc;
> - unsigned int i, head, found = 0;
> - u16 last_avail_idx;
> + unsigned int i = head, found = 0;
> int ret;
>
> - /* Check it isn't doing very strange things with descriptor numbers. */
> - last_avail_idx = vq->last_avail_idx;
> - if (get_user(vq->avail_idx, &vq->avail->idx)) {
> - vq_err(vq, "Failed to access avail idx at %p\n",
> - &vq->avail->idx);
> - return vq->num;
> - }
> -
> - if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) {
> - vq_err(vq, "Guest moved used index from %u to %u",
> - last_avail_idx, vq->avail_idx);
> - return vq->num;
> - }
> -
> - /* If there's nothing new since last we looked, return invalid. */
> - if (vq->avail_idx == last_avail_idx)
> - return vq->num;
> -
> - /* Only get avail ring entries after they have been exposed by guest. */
> - rmb();
> -
> - /* Grab the next descriptor number they're advertising, and increment
> - * the index we've seen. */
> - if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) {
> - vq_err(vq, "Failed to read head: idx %d address %p\n",
> - last_avail_idx,
> - &vq->avail->ring[last_avail_idx % vq->num]);
> - return vq->num;
> - }
> -
> - /* If their number is silly, that's an error. */
> - if (head >= vq->num) {
> - vq_err(vq, "Guest says index %u > %u is available",
> - head, vq->num);
> - return vq->num;
> - }
> -
> /* When we start there are none of either input nor output. */
> *out_num = *in_num = 0;
> if (unlikely(log))
> *log_num = 0;
>
> - i = head;
> do {
> unsigned iov_count = *in_num + *out_num;
> if (i >= vq->num) {
> @@ -833,8 +788,70 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
> *out_num += ret;
> }
> } while ((i = next_desc(&desc)) != -1);
> + return head;
> +}
> +
> +/* This looks in the virtqueue and for the first available buffer, and converts
> + * it to an iovec for convenient access. Since descriptors consist of some
> + * number of output then some number of input descriptors, it's actually two
> + * iovecs, but we pack them into one and note how many of each there were.
> + *
> + * This function returns the descriptor number found, or vq->num (which
> + * is never a valid descriptor number) if none was found. */
> +unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
> + struct iovec iov[], unsigned int iov_size,
> + unsigned int *out_num, unsigned int *in_num,
> + struct vhost_log *log, unsigned int *log_num)
> +{
> + struct vring_desc desc;
> + unsigned int i, head, found = 0;
> + u16 last_avail_idx;
> + unsigned int ret;
> +
> + /* Check it isn't doing very strange things with descriptor numbers. */
> + last_avail_idx = vq->last_avail_idx;
> + if (get_user(vq->avail_idx, &vq->avail->idx)) {
> + vq_err(vq, "Failed to access avail idx at %p\n",
> + &vq->avail->idx);
> + return vq->num;
> + }
> +
> + if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) {
> + vq_err(vq, "Guest moved used index from %u to %u",
> + last_avail_idx, vq->avail_idx);
> + return vq->num;
> + }
> +
> + /* If there's nothing new since last we looked, return invalid. */
> + if (vq->avail_idx == last_avail_idx)
> + return vq->num;
> +
> + /* Only get avail ring entries after they have been exposed by guest. */
> + rmb();
> +
> + /* Grab the next descriptor number they're advertising, and increment
> + * the index we've seen. */
> + if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) {
> + vq_err(vq, "Failed to read head: idx %d address %p\n",
> + last_avail_idx,
> + &vq->avail->ring[last_avail_idx % vq->num]);
> + return vq->num;
> + }
> +
> + /* If their number is silly, that's an error. */
> + if (head >= vq->num) {
> + vq_err(vq, "Guest says index %u > %u is available",
> + head, vq->num);
> + return vq->num;
> + }
> +
> + ret = __vhost_get_vq_desc(dev, vq, iov, iov_size,
> + out_num, in_num,
> + log, log_num, head);
>
> /* On success, increment avail index. */
> + if (ret == vq->num)
> + return ret;
> vq->last_avail_idx++;
> return head;
> }
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index d1f0453..8b95df8 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -43,6 +43,11 @@ struct vhost_log {
> u64 len;
> };
>
> +enum vhost_vq_link_state {
> + VHOST_VQ_LINK_SYNC = 0,
> + VHOST_VQ_LINK_ASYNC = 1,
don't try to align values to the right, just put a single space each
side of =.
> +};
> +
> /* The virtqueue structure describes a queue attached to a device. */
> struct vhost_virtqueue {
> struct vhost_dev *dev;
> @@ -96,6 +101,10 @@ struct vhost_virtqueue {
> /* Log write descriptors */
> void __user *log_base;
> struct vhost_log log[VHOST_NET_MAX_SG];
> + /*Differiate async socket for 0-copy from normal*/
spaces after /* and before */.
> + enum vhost_vq_link_state link_state;
> + struct list_head notifier;
> + spinlock_t notify_lock;
> };
>
> struct vhost_dev {
> @@ -122,6 +131,11 @@ unsigned vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
> struct iovec iov[], unsigned int iov_count,
> unsigned int *out_num, unsigned int *in_num,
> struct vhost_log *log, unsigned int *log_num);
> +unsigned __vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
> + struct iovec iov[], unsigned int iov_count,
> + unsigned int *out_num, unsigned int *in_num,
> + struct vhost_log *log, unsigned int *log_num,
> + unsigned int head);
> void vhost_discard_vq_desc(struct vhost_virtqueue *);
>
> int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
> --
> 1.5.4.4
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