diff options
| author | Jason Wang <jasowang@redhat.com> | 2018-05-22 14:21:04 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-05-23 14:32:12 -0400 |
| commit | 2f3ab6221e4c87960347d65c7cab9bd917d1f637 (patch) | |
| tree | 5a4050742518ae4b6df94df2ee624e54636770cf | |
| parent | a43ad59a908055d288e524e559494805a6c7299e (diff) | |
tuntap: correctly set SOCKWQ_ASYNC_NOSPACE
When link is down, writes to the device might fail with
-EIO. Userspace needs an indication when the status is resolved. As a
fix, tun_net_open() attempts to wake up writers - but that is only
effective if SOCKWQ_ASYNC_NOSPACE has been set in the past. This is
not the case of vhost_net which only poll for EPOLLOUT after it meets
errors during sendmsg().
This patch fixes this by making sure SOCKWQ_ASYNC_NOSPACE is set when
socket is not writable or device is down to guarantee EPOLLOUT will be
raised in either tun_chr_poll() or tun_sock_write_space() after device
is up.
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Eric Dumazet <edumazet@google.com>
Fixes: 1bd4978a88ac2 ("tun: honor IFF_UP in tun_get_user()")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/tun.c | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index d45ac37e1287..45d807796a18 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1423,6 +1423,13 @@ static void tun_net_init(struct net_device *dev) dev->max_mtu = MAX_MTU - dev->hard_header_len; } +static bool tun_sock_writeable(struct tun_struct *tun, struct tun_file *tfile) +{ + struct sock *sk = tfile->socket.sk; + + return (tun->dev->flags & IFF_UP) && sock_writeable(sk); +} + /* Character device part */ /* Poll */ @@ -1445,10 +1452,14 @@ static __poll_t tun_chr_poll(struct file *file, poll_table *wait) if (!ptr_ring_empty(&tfile->tx_ring)) mask |= EPOLLIN | EPOLLRDNORM; - if (tun->dev->flags & IFF_UP && - (sock_writeable(sk) || - (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags) && - sock_writeable(sk)))) + /* Make sure SOCKWQ_ASYNC_NOSPACE is set if not writable to + * guarantee EPOLLOUT to be raised by either here or + * tun_sock_write_space(). Then process could get notification + * after it writes to a down device and meets -EIO. + */ + if (tun_sock_writeable(tun, tfile) || + (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags) && + tun_sock_writeable(tun, tfile))) mask |= EPOLLOUT | EPOLLWRNORM; if (tun->dev->reg_state != NETREG_REGISTERED) |