diff options
| author | Jason Wang <jasowang@redhat.com> | 2018-05-22 09:21:04 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-11 20:02:54 +0300 |
| commit | 380a732d1792ab887669f6b5ab438ccad6cc1adb (patch) | |
| tree | 6e4bf82a4daab7d87a6ef29f72a1e6752631abba /drivers/net/tun.c | |
| parent | 0bdc63911545438223d5e44f869e3b1d9981a08b (diff) | |
| download | linux-380a732d1792ab887669f6b5ab438ccad6cc1adb.tar.xz | |
tuntap: correctly set SOCKWQ_ASYNC_NOSPACE
commit 2f3ab6221e4c87960347d65c7cab9bd917d1f637 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Diffstat (limited to 'drivers/net/tun.c')
| -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 3086211829a7..ba34f61d70de 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1134,6 +1134,13 @@ 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 */ @@ -1156,10 +1163,14 @@ static unsigned int tun_chr_poll(struct file *file, poll_table *wait) if (!skb_array_empty(&tfile->tx_array)) mask |= POLLIN | POLLRDNORM; - 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 |= POLLOUT | POLLWRNORM; if (tun->dev->reg_state != NETREG_REGISTERED) |