tun: fix tun_chr_aio_write so that aio works

aio_write gets const struct iovec * but tun_chr_aio_write casts this to struct
iovec * and modifies the iovec. As a result, attempts to use io_submit
to send packets to a tun device fail with weird errors such as EINVAL.

Since tun is the only user of skb_copy_datagram_from_iovec, we can
fix this simply by changing the later so that it does not
touch the iovec passed to it.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index af2b21bdda83..1b5c3d298f43 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1715,7 +1715,8 @@ extern int	       skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
                                                         struct iovec *iov);
 extern int             skb_copy_datagram_from_iovec(struct sk_buff *skb,
                                                     int offset,
-                                                    struct iovec *from,
+                                                    const struct iovec *from,
+                                                    int from_offset,
                                                     int len);
 extern int             skb_copy_datagram_const_iovec(const struct sk_buff *from,
                                                      int offset,