From: "Michael S. Tsirkin" <mst@redhat.com>
To: David Miller <davem@davemloft.net>
Cc: jasowang@redhat.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, hannes@stressinduktion.org,
edumazet@google.com
Subject: Re: [PATCH net] tuntap: raise EPOLLOUT on device up
Date: Tue, 22 May 2018 01:08:23 +0300 [thread overview]
Message-ID: <20180522010700-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20180521.114742.427929977852677864.davem@davemloft.net>
On Mon, May 21, 2018 at 11:47:42AM -0400, David Miller wrote:
> From: Jason Wang <jasowang@redhat.com>
> Date: Fri, 18 May 2018 21:00:43 +0800
>
> > 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>
>
> I'm no so sure what to do with this patch.
>
> Like Michael says, this flag bit is only checks upon transmit which
> may or may not happen after this point. It doesn't seem to be
> guaranteed.
Jason, can't we detect a link up transition and respond accordingly?
What do you think?
--
MST
next prev parent reply other threads:[~2018-05-21 22:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-18 13:00 [PATCH net] tuntap: raise EPOLLOUT on device up Jason Wang
2018-05-18 13:13 ` Michael S. Tsirkin
2018-05-18 13:26 ` Jason Wang
2018-05-18 14:00 ` Jason Wang
2018-05-18 14:06 ` Michael S. Tsirkin
2018-05-18 14:11 ` Jason Wang
2018-05-18 14:46 ` Michael S. Tsirkin
2018-05-19 1:09 ` Jason Wang
2018-05-21 22:06 ` Michael S. Tsirkin
2018-05-21 15:47 ` David Miller
2018-05-21 22:08 ` Michael S. Tsirkin [this message]
2018-05-22 3:22 ` Jason Wang
2018-05-22 3:45 ` Michael S. Tsirkin
2018-05-22 3:46 ` Michael S. Tsirkin
2018-05-22 4:00 ` Jason Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180522010700-mutt-send-email-mst@kernel.org \
--to=mst@redhat.com \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=hannes@stressinduktion.org \
--cc=jasowang@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).