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Commit d5675bd2 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

vhost: break out of polling loop on error 



When ring parsing fails, we currently handle this
as ring empty condition. This means that we enable
kicks and recheck ring empty: if this not empty,
we re-start polling which of course will fail again.

Instead, let's return a negative error code and stop polling.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 38000a94

drivers/vhost/net.c

+10 −2
Original line number Diff line number Diff line
@@ -98,7 +98,8 @@ static void tx_poll_start(struct vhost_net *net, struct socket *sock) 
static void handle_tx(struct vhost_net *net)

{

	struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];

	unsigned head, out, in, s;

	unsigned out, in, s;

	int head;

	struct msghdr msg = {

		.msg_name = NULL,

		.msg_namelen = 0,
@@ -135,6 +136,9 @@ static void handle_tx(struct vhost_net *net) 
					 ARRAY_SIZE(vq->iov),

					 &out, &in,

					 NULL, NULL);

		/* On error, stop handling until the next kick. */

		if (head < 0)

			break;

		/* Nothing new?  Wait for eventfd to tell us they refilled. */

		if (head == vq->num) {

			wmem = atomic_read(&sock->sk->sk_wmem_alloc);
@@ -192,7 +196,8 @@ 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];

	unsigned head, out, in, log, s;

	unsigned out, in, log, s;

	int head;

	struct vhost_log *vq_log;

	struct msghdr msg = {

		.msg_name = NULL,
@@ -228,6 +233,9 @@ static void handle_rx(struct vhost_net *net) 
					 ARRAY_SIZE(vq->iov),

					 &out, &in,

					 vq_log, &log);

		/* On error, stop handling until the next kick. */

		if (head < 0)

			break;

		/* OK, now we need to know about added descriptors. */

		if (head == vq->num) {

			if (unlikely(vhost_enable_notify(vq))) {

drivers/vhost/vhost.c

+17 −16
Original line number Diff line number Diff line
@@ -873,9 +873,10 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, 
 * 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,

 * This function returns the descriptor number found, or vq->num (which is

 * never a valid descriptor number) if none was found.  A negative code is

 * returned on error. */

int 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)
@@ -890,13 +891,13 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 
	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;

		return -EFAULT;

	}



	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;

		return -EFAULT;

	}



	/* If there's nothing new since last we looked, return invalid. */
@@ -912,14 +913,14 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 
		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;

		return -EFAULT;

	}



	/* 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;

		return -EINVAL;

	}



	/* When we start there are none of either input nor output. */
@@ -933,19 +934,19 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 
		if (i >= vq->num) {

			vq_err(vq, "Desc index is %u > %u, head = %u",

			       i, vq->num, head);

			return vq->num;

			return -EINVAL;

		}

		if (++found > vq->num) {

			vq_err(vq, "Loop detected: last one at %u "

			       "vq size %u head %u\n",

			       i, vq->num, head);

			return vq->num;

			return -EINVAL;

		}

		ret = copy_from_user(&desc, vq->desc + i, sizeof desc);

		if (ret) {

			vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",

			       i, vq->desc + i);

			return vq->num;

			return -EFAULT;

		}

		if (desc.flags & VRING_DESC_F_INDIRECT) {

			ret = get_indirect(dev, vq, iov, iov_size,
@@ -954,7 +955,7 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 
			if (ret < 0) {

				vq_err(vq, "Failure detected "

				       "in indirect descriptor at idx %d\n", i);

				return vq->num;

				return ret;

			}

			continue;

		}
@@ -964,7 +965,7 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 
		if (ret < 0) {

			vq_err(vq, "Translation failure %d descriptor idx %d\n",

			       ret, i);

			return vq->num;

			return ret;

		}

		if (desc.flags & VRING_DESC_F_WRITE) {

			/* If this is an input descriptor,
@@ -981,7 +982,7 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, 
			if (*in_num) {

				vq_err(vq, "Descriptor has out after in: "

				       "idx %d\n", i);

				return vq->num;

				return -EINVAL;

			}

			*out_num += ret;

		}

drivers/vhost/vhost.h

+4 −4
Original line number Diff line number Diff line
@@ -120,7 +120,7 @@ long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg); 
int vhost_vq_access_ok(struct vhost_virtqueue *vq);

int vhost_log_access_ok(struct vhost_dev *);



unsigned vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,

int 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);