[PATCH net-next V5 8/9] tap: support receiving skb from msg_control

Jason Wang
2017-05-17T04:15:45Z

This patch makes tap_recvmsg() can receive from skb from its caller
through msg_control. Vhost_net will be the first user.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/net/tap.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index abdaf86..9af3239 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -824,15 +824,17 @@ static ssize_t tap_put_user(struct tap_queue *q,

static ssize_t tap_do_read(struct tap_queue *q,
struct iov_iter *to,
- int noblock)
+ int noblock, struct sk_buff *skb)
{
DEFINE_WAIT(wait);
- struct sk_buff *skb;
ssize_t ret = 0;

if (!iov_iter_count(to))
return 0;

+ if (skb)
+ goto put;
+
while (1) {
if (!noblock)
prepare_to_wait(sk_sleep(&q->sk), &wait,
@@ -856,6 +858,7 @@ static ssize_t tap_do_read(struct tap_queue *q,
if (!noblock)
finish_wait(sk_sleep(&q->sk), &wait);

+put:
if (skb) {
ret = tap_put_user(q, skb, to);
if (unlikely(ret < 0))
@@ -872,7 +875,7 @@ static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
struct tap_queue *q = file->private_data;
ssize_t len = iov_iter_count(to), ret;

- ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK);
+ ret = tap_do_read(q, to, file->f_flags & O_NONBLOCK, NULL);
ret = min_t(ssize_t, ret, len);
if (ret > 0)
iocb->ki_pos = ret;
@@ -1155,7 +1158,8 @@ static int tap_recvmsg(struct socket *sock, struct msghdr *m,
int ret;
if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
return -EINVAL;
- ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT);
+ ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT,
+ m->msg_control);
if (ret > total_len) {
m->msg_flags |= MSG_TRUNC;
ret = flags & MSG_TRUNC ? ret : total_len;
--
2.7.4