Messages in this thread | | | Date | Fri, 18 May 2018 17:06:23 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH net] tuntap: raise EPOLLOUT on device up |
| |
On Fri, May 18, 2018 at 10:00:31PM +0800, Jason Wang wrote: > > > On 2018年05月18日 21:26, Jason Wang wrote: > > > > > > On 2018年05月18日 21:13, Michael S. Tsirkin wrote: > > > On Fri, May 18, 2018 at 09:00:43PM +0800, Jason Wang wrote: > > > > 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 <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> > > > > --- > > > > 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)) { > > > Isn't this racy? What if flag is cleared at this point? > > > > I think you mean "set at this point"? Then yes, so we probably need to > > set the bit during tun_net_close(). > > > > Thanks > > Looks no need, vhost will poll socket after it see EIO. So we are ok here? > > Thanks
In fact I don't even understand why does this help any longer.
-- MST
| |