tun: return proper error code from tun_do_read

Instead of -1 with EAGAIN, read on a O_NONBLOCK tun fd will return 0.  This
fixes this by properly returning the error code from __skb_recv_datagram.

Signed-off-by: Alex Gartrell <agartrell@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index df5e94871844..c0df872f5b8c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1380,7 +1380,7 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
         skb = __skb_recv_datagram(tfile->socket.sk, noblock ? MSG_DONTWAIT : 0,
                                   &peeked, &off, &err);
         if (!skb)
-                return 0;
+                return err;
 
         ret = tun_put_user(tun, tfile, skb, to);
         if (unlikely(ret < 0))