On Thu, Mar 30, 2017 at 03:22:28PM +0800, Jason Wang wrote:
> 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 <jasow...@redhat.com>
Do we need to bother with tun? I didn't realize one
can even use that with vhost. What would be the point of
all the virtio header stuff dealing with checksums etc?
Even if you see a use-case is it worth optimizing?
> ---
> 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 70dd9ec..a82bced 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1498,9 +1498,8 @@ 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;
>
> @@ -1509,10 +1508,12 @@ 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))
> @@ -1532,7 +1533,7 @@ 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;
> @@ -1634,7 +1635,8 @@ 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
