Re: [PATCH V2 net-next 5/7] tun: support receiving skb through msg_control
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2017-03-30 15:06:38
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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 <jasowang@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?
quoted hunk ↗ jump to hunk
--- 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