[PATCH net-next V5 7/9] tun: support receiving skb through msg_control

Jason Wang
2017-05-17T04:16:43Z

This patch makes tun_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/tun.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 3cbfc5c..f8041f9c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1510,9 +1510,8 @@ static struct sk_buff *tun_ring_recv(struct tun_file *tfile, int noblock,

static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
struct iov_iter *to,
- int noblock)
+ int noblock, struct sk_buff *skb)
{
- struct sk_buff *skb;
ssize_t ret;
int err;

@@ -1521,10 +1520,12 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
if (!iov_iter_count(to))
return 0;

- /* Read frames from ring */
- skb = tun_ring_recv(tfile, noblock, &err);
- if (!skb)
- return err;
+ if (!skb) {
+ /* Read frames from ring */
+ skb = tun_ring_recv(tfile, noblock, &err);
+ if (!skb)
+ return err;
+ }

ret = tun_put_user(tun, tfile, skb, to);
if (unlikely(ret < 0))
@@ -1544,7 +1545,7 @@ static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)

if (!tun)
return -EBADFD;
- ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK);
+ ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK, NULL);
ret = min_t(ssize_t, ret, len);
if (ret > 0)
iocb->ki_pos = ret;
@@ -1646,7 +1647,8 @@ static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len,
SOL_PACKET, TUN_TX_TIMESTAMP);
goto out;
}
- ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT);
+ ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT,
+ m->msg_control);
if (ret > (ssize_t)total_len) {
m->msg_flags |= MSG_TRUNC;
ret = flags & MSG_TRUNC ? ret : total_len;
--
2.7.4