We return -EIO on device down but can not raise EPOLLOUT after it was
up. This may confuse user like vhost which expects tuntap to raise
EPOLLOUT to re-enable its TX routine after tuntap is down. This could
be easily reproduced by transmitting packets from VM while down and up
the tap device. Fixing this by set SOCKWQ_ASYNC_NOSPACE on -EIO.
Cc: Hannes Frederic Sowa <han...@stressinduktion.org>
Cc: Eric Dumazet <eduma...@google.com>
Fixes: 1bd4978a88ac2 ("tun: honor IFF_UP in tun_get_user()")
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
drivers/net/tun.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d45ac37..1b29761 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1734,8 +1734,10 @@ static ssize_t tun_get_user(struct tun_struct *tun,
struct tun_file *tfile,
int skb_xdp = 1;
bool frags = tun_napi_frags_enabled(tun);
- if (!(tun->dev->flags & IFF_UP))
+ if (!(tun->dev->flags & IFF_UP)) {
+ set_bit(SOCKWQ_ASYNC_NOSPACE, &tfile->socket.flags);
return -EIO;
+ }
if (!(tun->flags & IFF_NO_PI)) {
if (len < sizeof(pi))
--
2.7.4
