David Stevens
2010-Mar-03 00:20 UTC
[RFC][ PATCH 2/3] vhost-net: handle vnet_hdr processing for MRG_RX_BUF
This patch adds vnet_hdr processing for mergeable buffer
support to vhost-net.
Signed-off-by: David L Stevens <dlstevens at us.ibm.com>
diff -ruN net-next-p1/drivers/vhost/net.c net-next-p2/drivers/vhost/net.c
--- net-next-p1/drivers/vhost/net.c 2010-03-01 11:44:22.000000000
-0800
+++ net-next-p2/drivers/vhost/net.c 2010-03-02 13:01:34.000000000
-0800
@@ -109,7 +109,6 @@
};
size_t len, total_len = 0;
int err, wmem;
- size_t hdr_size;
struct socket *sock = rcu_dereference(vq->private_data);
if (!sock)
return;
@@ -124,7 +123,6 @@
if (wmem < sock->sk->sk_sndbuf * 2)
tx_poll_stop(net);
- hdr_size = vq->hdr_size;
for (;;) {
head.iov_base = (void *)vhost_get_vq_desc(&net->dev, vq,
@@ -148,25 +146,45 @@
"out %d, int %d\n", out, in);
break;
}
+ if (vq->guest_hlen > vq->sock_hlen) {
+ if (msg.msg_iov[0].iov_len == vq->guest_hlen)
+ msg.msg_iov[0].iov_len = vq->sock_hlen;
+ else if (out == ARRAY_SIZE(vq->iov))
+ vq_err(vq, "handle_tx iov overflow!");
+ else {
+ int i;
+
+ /* give header its own iov */
+ for (i=out; i>0; ++i)
+ msg.msg_iov[i+1] = msg.msg_iov[i];
+ msg.msg_iov[0].iov_len = vq->sock_hlen;
+ msg.msg_iov[1].iov_base += vq->guest_hlen;
+ msg.msg_iov[1].iov_len -= vq->guest_hlen;
+ out++;
+ }
+ }
/* Skip header. TODO: support TSO. */
- s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
msg.msg_iovlen = out;
head.iov_len = len = iov_length(vq->iov, out);
/* Sanity check */
if (!len) {
vq_err(vq, "Unexpected header len for TX: "
"%zd expected %zd\n",
- iov_length(vq->hdr, s), hdr_size);
+ len, vq->guest_hlen);
break;
}
/* TODO: Check specific error and bomb out unless ENOBUFS?
*/
err = sock->ops->sendmsg(NULL, sock, &msg, len);
if (unlikely(err < 0)) {
- vhost_discard(vq, 1);
- tx_poll_start(net, sock);
+ if (err == -EAGAIN) {
+ tx_poll_start(net, sock);
+ } else {
+ vq_err(vq, "sendmsg: errno %d\n",
-err);
+ /* drop packet; do not discard/resend */
+ vhost_add_used_and_signal(&net->dev,vq,&head,1);
+ }
break;
- }
- if (err != len)
+ } else if (err != len)
pr_err("Truncated TX packet: "
" len %d != %zd\n", err, len);
vhost_add_used_and_signal(&net->dev, vq, &head, 1);
@@ -207,14 +225,8 @@
.msg_flags = MSG_DONTWAIT,
};
- struct virtio_net_hdr hdr = {
- .flags = 0,
- .gso_type = VIRTIO_NET_HDR_GSO_NONE
- };
-
size_t len, total_len = 0;
int err, headcount, datalen;
- size_t hdr_size;
struct socket *sock = rcu_dereference(vq->private_data);
if (!sock || !skb_head_len(&sock->sk->sk_receive_queue))
@@ -223,7 +235,6 @@
use_mm(net->dev.mm);
mutex_lock(&vq->mutex);
vhost_disable_notify(vq);
- hdr_size = vq->hdr_size;
vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL))
?
vq->log : NULL;
@@ -232,25 +243,18 @@
headcount = vhost_get_heads(vq, datalen, &in, vq_log,
&log);
/* OK, now we need to know about added descriptors. */
if (!headcount) {
- if (unlikely(vhost_enable_notify(vq))) {
- /* They have slipped one in as we were
- * doing that: check again. */
- vhost_disable_notify(vq);
- continue;
- }
- /* Nothing new? Wait for eventfd to tell us
- * they refilled. */
+ vhost_enable_notify(vq);
break;
}
/* Skip header. TODO: support TSO/mergeable rx buffers. */
- s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
msg.msg_iovlen = in;
len = iov_length(vq->iov, in);
+
/* Sanity check */
if (!len) {
vq_err(vq, "Unexpected header len for RX: "
"%zd expected %zd\n",
- iov_length(vq->hdr, s), hdr_size);
+ len, vq->guest_hlen);
break;
}
err = sock->ops->recvmsg(NULL, sock, &msg,
@@ -268,13 +272,7 @@
continue;
}
len = err;
- err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr,
hdr_size);
- if (err) {
- vq_err(vq, "Unable to write vnet_hdr at addr %p:
%d\n",
- vq->iov->iov_base, err);
- break;
- }
- len += hdr_size;
+ len += vq->guest_hlen - vq->sock_hlen;
vhost_add_used_and_signal(&net->dev, vq, vq->heads,
headcount);
if (unlikely(vq_log))
vhost_log_write(vq, vq_log, log, len);
@@ -483,6 +481,13 @@
return ERR_PTR(-ENOTSOCK);
}
+static int vhost_sock_is_raw(struct socket *sock)
+{
+ if (!sock || !sock->sk)
+ return 0;
+ return sock->sk->sk_type == SOCK_RAW;
+}
+
static long vhost_net_set_backend(struct vhost_net *n, unsigned index,
int fd)
{
struct socket *sock, *oldsock;
@@ -519,6 +524,20 @@
vhost_net_disable_vq(n, vq);
rcu_assign_pointer(vq->private_data, sock);
+
+ if (sock && sock->sk) {
+ if (!vhost_sock_is_raw(sock) ||
+ vhost_has_feature(&n->dev,
VHOST_NET_F_VIRTIO_NET_HDR)) {
+ vq->sock_hlen = sizeof(struct virtio_net_hdr);
+ if (vhost_has_feature(&n->dev,
VIRTIO_NET_F_MRG_RXBUF))
+ vq->guest_hlen +
sizeof(struct
virtio_net_hdr_mrg_rxbuf);
+ else
+ vq->guest_hlen = sizeof(struct
virtio_net_hdr);
+ } else
+ vq->guest_hlen = vq->sock_hlen = 0;
+ } else
+ vq_err(vq, "vhost_net_set_backend: sock->sk is
NULL");
vhost_net_enable_vq(n, vq);
mutex_unlock(&vq->mutex);
done:
@@ -566,8 +585,17 @@
n->dev.acked_features = features;
smp_wmb();
for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
- mutex_lock(&n->vqs[i].mutex);
- n->vqs[i].hdr_size = hdr_size;
+ struct vhost_virtqueue *vq = n->vqs + i;
+ struct socket *sock = vq->private_data;
+
+ mutex_lock(&vq->mutex);
+ if (features & (1 << VIRTIO_NET_F_MRG_RXBUF))
+ vq->sock_hlen = sizeof(struct
virtio_net_hdr_mrg_rxbuf);
+ else if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)
||
+ !vhost_sock_is_raw(sock))
+ vq->sock_hlen = sizeof(struct virtio_net_hdr);
+ else
+ vq->sock_hlen = 0;
mutex_unlock(&n->vqs[i].mutex);
}
vhost_net_flush(n);
diff -ruN net-next-p1/drivers/vhost/vhost.c
net-next-p2/drivers/vhost/vhost.c
--- net-next-p1/drivers/vhost/vhost.c 2010-03-01 11:44:06.000000000
-0800
+++ net-next-p2/drivers/vhost/vhost.c 2010-03-02 12:53:02.000000000
-0800
@@ -113,7 +113,8 @@
vq->used_flags = 0;
vq->log_used = false;
vq->log_addr = -1ull;
- vq->hdr_size = 0;
+ vq->guest_hlen = 0;
+ vq->sock_hlen = 0;
vq->private_data = NULL;
vq->log_base = NULL;
vq->error_ctx = NULL;
@@ -848,20 +849,85 @@
return 0;
}
+static int
+vhost_get_hdr(struct vhost_virtqueue *vq, int *in, struct vhost_log *log,
+ int *log_num)
+{
+ struct iovec *heads = vq->heads;
+ struct iovec *iov = vq->iov;
+ int out;
+
+ *in = 0;
+ iov[0].iov_len = 0;
+
+ /* get buffer, starting from iov[1] */
+ heads[0].iov_base = (void *)vhost_get_vq_desc(vq->dev, vq,
+ vq->iov+1, ARRAY_SIZE(vq->iov)-1, &out, in, log,
log_num);
+ if (out || *in <= 0) {
+ vq_err(vq, "unexpected descriptor format for RX: out %d,
"
+ "in %d\n", out, *in);
+ return 0;
+ }
+ if (heads[0].iov_base == (void *)vq->num)
+ return 0;
+
+ /* make iov[0] the header */
+ if (!vq->guest_hlen) {
+ if (vq->sock_hlen) {
+ static struct virtio_net_hdr junk; /* bit bucket
*/
+
+ iov[0].iov_base = &junk;
+ iov[0].iov_len = sizeof(junk);
+ } else
+ iov[0].iov_len = 0;
+ }
+ if (vq->sock_hlen < vq->guest_hlen) {
+ iov[0].iov_base = iov[1].iov_base;
+ iov[0].iov_len = vq->sock_hlen;
+
+ if (iov[1].iov_len < vq->sock_hlen) {
+ vq_err(vq, "can't fit header in one
buffer!");
+ vhost_discard(vq, 1);
+ return 0;
+ }
+ if (!vq->sock_hlen) {
+ static const struct virtio_net_hdr_mrg_rxbuf hdr =
{
+ .hdr.flags = 0,
+ .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
+ };
+ memcpy(iov[0].iov_base, &hdr, vq->guest_hlen);
+ }
+ iov[1].iov_base += vq->guest_hlen;
+ iov[1].iov_len -= vq->guest_hlen;
+ }
+ return 1;
+}
+
unsigned vhost_get_heads(struct vhost_virtqueue *vq, int datalen, int
*iovcount,
struct vhost_log *log, unsigned int *log_num)
{
struct iovec *heads = vq->heads;
- int out, in;
+ int out, in = 0;
+ int seg = 0;
int hc = 0;
+ if (vq->guest_hlen != vq->sock_hlen) {
+ seg = vhost_get_hdr(vq, &in, log, log_num);
+ if (!seg)
+ return 0;
+ hc++;
+ datalen -= iov_length(vq->iov+seg, in);
+ seg += in;
+ }
+
while (datalen > 0) {
if (hc >= VHOST_NET_MAX_SG) {
vhost_discard(vq, hc);
return 0;
}
heads[hc].iov_base = (void *)vhost_get_vq_desc(vq->dev,
vq,
- vq->iov, ARRAY_SIZE(vq->iov), &out, &in,
log,
log_num);
+ vq->iov+seg, ARRAY_SIZE(vq->iov)-seg, &out,
&in,
+ log, log_num);
if (heads[hc].iov_base == (void *)vq->num) {
vhost_discard(vq, hc);
return 0;
@@ -872,11 +938,12 @@
vhost_discard(vq, hc);
return 0;
}
- heads[hc].iov_len = iov_length(vq->iov, in);
- hc++;
+ heads[hc].iov_len = iov_length(vq->iov+seg, in);
datalen -= heads[hc].iov_len;
+ hc++;
+ seg += in;
}
- *iovcount = in;
+ *iovcount = seg;
return hc;
}
diff -ruN net-next-p1/drivers/vhost/vhost.h
net-next-p2/drivers/vhost/vhost.h
--- net-next-p1/drivers/vhost/vhost.h 2010-03-01 11:42:18.000000000
-0800
+++ net-next-p2/drivers/vhost/vhost.h 2010-03-02 13:02:03.000000000
-0800
@@ -82,10 +82,9 @@
u64 log_addr;
struct iovec indirect[VHOST_NET_MAX_SG];
- struct iovec iov[VHOST_NET_MAX_SG];
- struct iovec hdr[VHOST_NET_MAX_SG];
+ struct iovec iov[VHOST_NET_MAX_SG+1]; /* an extra for vnet hdr */
struct iovec heads[VHOST_NET_MAX_SG];
- size_t hdr_size;
+ size_t guest_hlen, sock_hlen;
/* We use a kind of RCU to access private pointer.
* All readers access it from workqueue, which makes it possible
to
* flush the workqueue instead of synchronize_rcu. Therefore
readers do
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Michael S. Tsirkin
2010-Mar-07 16:12 UTC
[RFC][ PATCH 2/3] vhost-net: handle vnet_hdr processing for MRG_RX_BUF
On Tue, Mar 02, 2010 at 05:20:26PM -0700, David Stevens wrote:> This patch adds vnet_hdr processing for mergeable buffer > support to vhost-net. > > Signed-off-by: David L Stevens <dlstevens at us.ibm.com> > > diff -ruN net-next-p1/drivers/vhost/net.c net-next-p2/drivers/vhost/net.cCould you please add -p to diff flags so that it's easier to figure out which function is changes?> --- net-next-p1/drivers/vhost/net.c 2010-03-01 11:44:22.000000000 > -0800 > +++ net-next-p2/drivers/vhost/net.c 2010-03-02 13:01:34.000000000 > -0800 > @@ -109,7 +109,6 @@ > }; > size_t len, total_len = 0; > int err, wmem; > - size_t hdr_size; > struct socket *sock = rcu_dereference(vq->private_data); > if (!sock) > return; > @@ -124,7 +123,6 @@ > > if (wmem < sock->sk->sk_sndbuf * 2) > tx_poll_stop(net); > - hdr_size = vq->hdr_size; > > for (;;) { > head.iov_base = (void *)vhost_get_vq_desc(&net->dev, vq, > @@ -148,25 +146,45 @@ > "out %d, int %d\n", out, in); > break; > } > + if (vq->guest_hlen > vq->sock_hlen) { > + if (msg.msg_iov[0].iov_len == vq->guest_hlen) > + msg.msg_iov[0].iov_len = vq->sock_hlen; > + else if (out == ARRAY_SIZE(vq->iov)) > + vq_err(vq, "handle_tx iov overflow!"); > + else { > + int i; > + > + /* give header its own iov */ > + for (i=out; i>0; ++i) > + msg.msg_iov[i+1] = msg.msg_iov[i]; > + msg.msg_iov[0].iov_len = vq->sock_hlen; > + msg.msg_iov[1].iov_base += vq->guest_hlen; > + msg.msg_iov[1].iov_len -= vq->guest_hlen; > + out++;We seem to spend a fair bit of code here and elsewhere trying to cover the diff between header size in guest and host. In hindsight, it was not a good idea to put new padding between data and the header: virtio-net should have added it *before*. But it is what it is. Wouldn't it be easier to just add an ioctl to tap so that vnet header size is made bigger by 4 bytes?> + } > + } > /* Skip header. TODO: support TSO. */ > - s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out); > msg.msg_iovlen = out; > head.iov_len = len = iov_length(vq->iov, out); > /* Sanity check */ > if (!len) { > vq_err(vq, "Unexpected header len for TX: " > "%zd expected %zd\n", > - iov_length(vq->hdr, s), hdr_size); > + len, vq->guest_hlen); > break; > } > /* TODO: Check specific error and bomb out unless ENOBUFS? > */ > err = sock->ops->sendmsg(NULL, sock, &msg, len); > if (unlikely(err < 0)) { > - vhost_discard(vq, 1); > - tx_poll_start(net, sock); > + if (err == -EAGAIN) {The comment mentions ENOBUFS. Are you sure it's EAGAIN?> + tx_poll_start(net, sock);Don't we need to call discard to move the last avail header back?> + } else { > + vq_err(vq, "sendmsg: errno %d\n", -err); > + /* drop packet; do not discard/resend */ > + vhost_add_used_and_signal(&net->dev,vq,&head,1); > + } > break; > - } > - if (err != len) > + } else if (err != len)Previous if ends with break so no need for else here.> pr_err("Truncated TX packet: " > " len %d != %zd\n", err, len); > vhost_add_used_and_signal(&net->dev, vq, &head, 1); > @@ -207,14 +225,8 @@ > .msg_flags = MSG_DONTWAIT, > }; > > - struct virtio_net_hdr hdr = { > - .flags = 0, > - .gso_type = VIRTIO_NET_HDR_GSO_NONE > - }; > - > size_t len, total_len = 0; > int err, headcount, datalen; > - size_t hdr_size; > struct socket *sock = rcu_dereference(vq->private_data); > > if (!sock || !skb_head_len(&sock->sk->sk_receive_queue)) > @@ -223,7 +235,6 @@ > use_mm(net->dev.mm); > mutex_lock(&vq->mutex); > vhost_disable_notify(vq); > - hdr_size = vq->hdr_size; > > vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ? > vq->log : NULL; > @@ -232,25 +243,18 @@ > headcount = vhost_get_heads(vq, datalen, &in, vq_log, > &log); > /* OK, now we need to know about added descriptors. */ > if (!headcount) { > - if (unlikely(vhost_enable_notify(vq))) { > - /* They have slipped one in as we were > - * doing that: check again. */ > - vhost_disable_notify(vq); > - continue; > - } > - /* Nothing new? Wait for eventfd to tell us > - * they refilled. */ > + vhost_enable_notify(vq);You don't think this race can happen?> break; > } > /* Skip header. TODO: support TSO/mergeable rx buffers. */ > - s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in); > msg.msg_iovlen = in; > len = iov_length(vq->iov, in); > + > /* Sanity check */ > if (!len) { > vq_err(vq, "Unexpected header len for RX: " > "%zd expected %zd\n", > - iov_length(vq->hdr, s), hdr_size); > + len, vq->guest_hlen); > break; > } > err = sock->ops->recvmsg(NULL, sock, &msg, > @@ -268,13 +272,7 @@ > continue; > } > len = err; > - err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, > hdr_size); > - if (err) { > - vq_err(vq, "Unable to write vnet_hdr at addr %p: > %d\n", > - vq->iov->iov_base, err); > - break; > - } > - len += hdr_size; > + len += vq->guest_hlen - vq->sock_hlen; > vhost_add_used_and_signal(&net->dev, vq, vq->heads, > headcount); > if (unlikely(vq_log)) > vhost_log_write(vq, vq_log, log, len); > @@ -483,6 +481,13 @@ > return ERR_PTR(-ENOTSOCK); > } > > +static int vhost_sock_is_raw(struct socket *sock) > +{ > + if (!sock || !sock->sk) > + return 0; > + return sock->sk->sk_type == SOCK_RAW; > +} > + > static long vhost_net_set_backend(struct vhost_net *n, unsigned index, > int fd) > { > struct socket *sock, *oldsock; > @@ -519,6 +524,20 @@ > > vhost_net_disable_vq(n, vq); > rcu_assign_pointer(vq->private_data, sock); > + > + if (sock && sock->sk) { > + if (!vhost_sock_is_raw(sock) ||I dislike this backend-specific code, it ties us with specifics of backend implementations, which change without notice. Ideally all backend-specific stuff should live in userspace, userspace programs vhost device appropriately.> + vhost_has_feature(&n->dev, > VHOST_NET_F_VIRTIO_NET_HDR)) { > + vq->sock_hlen = sizeof(struct virtio_net_hdr); > + if (vhost_has_feature(&n->dev, > VIRTIO_NET_F_MRG_RXBUF)) > + vq->guest_hlen > + sizeof(struct > virtio_net_hdr_mrg_rxbuf); > + else > + vq->guest_hlen = sizeof(struct > virtio_net_hdr); > + } else > + vq->guest_hlen = vq->sock_hlen = 0; > + } else > + vq_err(vq, "vhost_net_set_backend: sock->sk is NULL");As proposed above, IMO it would be nicer to add an ioctl in tap that let us program header size.> vhost_net_enable_vq(n, vq); > mutex_unlock(&vq->mutex); > done: > @@ -566,8 +585,17 @@ > n->dev.acked_features = features; > smp_wmb(); > for (i = 0; i < VHOST_NET_VQ_MAX; ++i) { > - mutex_lock(&n->vqs[i].mutex); > - n->vqs[i].hdr_size = hdr_size; > + struct vhost_virtqueue *vq = n->vqs + i; > + struct socket *sock = vq->private_data; > + > + mutex_lock(&vq->mutex); > + if (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) > + vq->sock_hlen = sizeof(struct > virtio_net_hdr_mrg_rxbuf); > + else if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR) || > + !vhost_sock_is_raw(sock)) > + vq->sock_hlen = sizeof(struct virtio_net_hdr); > + else > + vq->sock_hlen = 0; > mutex_unlock(&n->vqs[i].mutex); > } > vhost_net_flush(n); > diff -ruN net-next-p1/drivers/vhost/vhost.c > net-next-p2/drivers/vhost/vhost.c > --- net-next-p1/drivers/vhost/vhost.c 2010-03-01 11:44:06.000000000 > -0800 > +++ net-next-p2/drivers/vhost/vhost.c 2010-03-02 12:53:02.000000000 > -0800 > @@ -113,7 +113,8 @@ > vq->used_flags = 0; > vq->log_used = false; > vq->log_addr = -1ull; > - vq->hdr_size = 0; > + vq->guest_hlen = 0; > + vq->sock_hlen = 0; > vq->private_data = NULL; > vq->log_base = NULL; > vq->error_ctx = NULL; > @@ -848,20 +849,85 @@ > return 0; > } > > +static int > +vhost_get_hdr(struct vhost_virtqueue *vq, int *in, struct vhost_log *log, > + int *log_num) > +{ > + struct iovec *heads = vq->heads; > + struct iovec *iov = vq->iov; > + int out; > + > + *in = 0; > + iov[0].iov_len = 0; > + > + /* get buffer, starting from iov[1] */ > + heads[0].iov_base = (void *)vhost_get_vq_desc(vq->dev, vq, > + vq->iov+1, ARRAY_SIZE(vq->iov)-1, &out, in, log, log_num); > + if (out || *in <= 0) { > + vq_err(vq, "unexpected descriptor format for RX: out %d, " > + "in %d\n", out, *in); > + return 0; > + } > + if (heads[0].iov_base == (void *)vq->num) > + return 0; > + > + /* make iov[0] the header */ > + if (!vq->guest_hlen) { > + if (vq->sock_hlen) { > + static struct virtio_net_hdr junk; /* bit bucket > */ > + > + iov[0].iov_base = &junk; > + iov[0].iov_len = sizeof(junk); > + } else > + iov[0].iov_len = 0; > + } > + if (vq->sock_hlen < vq->guest_hlen) { > + iov[0].iov_base = iov[1].iov_base; > + iov[0].iov_len = vq->sock_hlen; > + > + if (iov[1].iov_len < vq->sock_hlen) { > + vq_err(vq, "can't fit header in one buffer!"); > + vhost_discard(vq, 1); > + return 0; > + } > + if (!vq->sock_hlen) { > + static const struct virtio_net_hdr_mrg_rxbuf hdr = > { > + .hdr.flags = 0, > + .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE > + }; > + memcpy(iov[0].iov_base, &hdr, vq->guest_hlen); > + } > + iov[1].iov_base += vq->guest_hlen; > + iov[1].iov_len -= vq->guest_hlen; > + } > + return 1;The above looks kind of scary, lots of special-casing. I'll send a patch for tap to set vnet header size, let's see if it makes life easier for us.> +} > + > unsigned vhost_get_heads(struct vhost_virtqueue *vq, int datalen, int > *iovcount, > struct vhost_log *log, unsigned int *log_num) > { > struct iovec *heads = vq->heads; > - int out, in; > + int out, in = 0; > + int seg = 0; > int hc = 0;I think it's better to stick to simple names like i for index variables, alternatively give it a meaningful name like "count".> > + if (vq->guest_hlen != vq->sock_hlen) {Sticking guest_hlen/sock_hlen in vhost is somewhat ugly.> + seg = vhost_get_hdr(vq, &in, log, log_num); > + if (!seg) > + return 0; > + hc++; > + datalen -= iov_length(vq->iov+seg, in); > + seg += in; > + } > + > while (datalen > 0) { > if (hc >= VHOST_NET_MAX_SG) { > vhost_discard(vq, hc); > return 0; > } > heads[hc].iov_base = (void *)vhost_get_vq_desc(vq->dev, > vq, > - vq->iov, ARRAY_SIZE(vq->iov), &out, &in, log, > log_num); > + vq->iov+seg, ARRAY_SIZE(vq->iov)-seg, &out, &in, > + log, log_num); > if (heads[hc].iov_base == (void *)vq->num) { > vhost_discard(vq, hc); > return 0; > @@ -872,11 +938,12 @@ > vhost_discard(vq, hc); > return 0; > } > - heads[hc].iov_len = iov_length(vq->iov, in); > - hc++; > + heads[hc].iov_len = iov_length(vq->iov+seg, in); > datalen -= heads[hc].iov_len; > + hc++; > + seg += in; > } > - *iovcount = in; > + *iovcount = seg; > return hc; > } > > diff -ruN net-next-p1/drivers/vhost/vhost.h > net-next-p2/drivers/vhost/vhost.h > --- net-next-p1/drivers/vhost/vhost.h 2010-03-01 11:42:18.000000000 > -0800 > +++ net-next-p2/drivers/vhost/vhost.h 2010-03-02 13:02:03.000000000 > -0800 > @@ -82,10 +82,9 @@ > u64 log_addr; > > struct iovec indirect[VHOST_NET_MAX_SG]; > - struct iovec iov[VHOST_NET_MAX_SG]; > - struct iovec hdr[VHOST_NET_MAX_SG]; > + struct iovec iov[VHOST_NET_MAX_SG+1]; /* an extra for vnet hdr */ > struct iovec heads[VHOST_NET_MAX_SG]; > - size_t hdr_size; > + size_t guest_hlen, sock_hlen; > /* We use a kind of RCU to access private pointer. > * All readers access it from workqueue, which makes it possible > to > * flush the workqueue instead of synchronize_rcu. Therefore > readers do >
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