From: Wei Wang <weiwan@google.com>
To: Martin Lau <kafai@fb.com>
Cc: Jesse Hathaway <jesse@mbuki-mvuki.org>,
Ido Schimmel <idosch@idosch.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>
Subject: Re: Race condition in route lookup
Date: Wed, 16 Oct 2019 09:35:50 -0700 [thread overview]
Message-ID: <CAEA6p_AUxd+y9rXQ2RkggTqwmvkxDdDdrmQ=XEj4XEtn1ZFRkg@mail.gmail.com> (raw)
In-Reply-To: <20191016063928.rwxe65paunw3jwel@kafai-mbp.dhcp.thefacebook.com>
On Tue, Oct 15, 2019 at 11:39 PM Martin Lau <kafai@fb.com> wrote:
>
> On Tue, Oct 15, 2019 at 09:44:11AM -0700, Wei Wang wrote:
> > On Tue, Oct 15, 2019 at 7:29 AM Jesse Hathaway <jesse@mbuki-mvuki.org> wrote:
> > >
> > > On Fri, Oct 11, 2019 at 12:54 PM Wei Wang <weiwan@google.com> wrote:
> > > > Hmm... Yes... I would think a per-CPU input cache should work for the
> > > > case above.
> > > > Another idea is: instead of calling dst_dev_put() in rt_cache_route()
> > > > to switch out the dev, we call, rt_add_uncached_list() to add this
> > > > obsolete dst cache to the uncached list. And if the device gets
> > > > unregistered, rt_flush_dev() takes care of all dst entries in the
> > > > uncached list. I think that would work too.
> > > >
> > > > diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> > > > index dc1f510a7c81..ee618d4234ce 100644
> > > > --- a/net/ipv4/route.c
> > > > +++ b/net/ipv4/route.c
> > > > @@ -1482,7 +1482,7 @@ static bool rt_cache_route(struct fib_nh_common
> > > > *nhc, struct rtable *rt)
> > > > prev = cmpxchg(p, orig, rt);
> > > > if (prev == orig) {
> > > > if (orig) {
> > > > - dst_dev_put(&orig->dst);
> > > > + rt_add_uncached_list(orig);
> > > > dst_release(&orig->dst);
> > > > }
> > > > } else {
> > > >
> > >
> > > Thanks Wei for your work on this issue,
> > >
> > > Any chance this patch will make it into 5.4?
> >
> > I can submit the patch to NET branch if everyone agrees with this one liner fix.
> Acked-by: Martin KaFai Lau <kafai@fb.com>
>
> I don't think it is a very critical bug though. Not sure
> how far it should be ported.
>
Thanks Martin. I am preparing the patch and will send it out soon.
> > Then I believe it will be patched into the next 5.4 release automatically?
prev parent reply other threads:[~2019-10-16 16:36 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 16:00 Race condition in route lookup Jesse Hathaway
2019-10-10 8:31 ` Ido Schimmel
2019-10-10 8:46 ` Ido Schimmel
2019-10-11 14:36 ` Jesse Hathaway
2019-10-11 15:42 ` Ido Schimmel
2019-10-11 16:09 ` Jesse Hathaway
2019-10-11 17:54 ` Wei Wang
2019-10-11 18:17 ` Ido Schimmel
2019-10-11 18:25 ` Ido Schimmel
2019-10-11 18:47 ` Wei Wang
2019-10-11 18:52 ` Ido Schimmel
2019-10-11 21:01 ` Jesse Hathaway
2019-10-11 21:27 ` David Ahern
2019-10-12 6:56 ` Martin Lau
2019-10-14 0:23 ` Wei Wang
2019-10-14 17:26 ` Martin Lau
2019-10-15 14:45 ` David Ahern
2019-10-15 16:42 ` Wei Wang
2019-10-16 6:35 ` Martin Lau
2019-10-15 14:29 ` Jesse Hathaway
2019-10-15 16:44 ` Wei Wang
2019-10-16 6:39 ` Martin Lau
2019-10-16 16:35 ` Wei Wang [this message]
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='CAEA6p_AUxd+y9rXQ2RkggTqwmvkxDdDdrmQ=XEj4XEtn1ZFRkg@mail.gmail.com' \
--to=weiwan@google.com \
--cc=idosch@idosch.org \
--cc=jesse@mbuki-mvuki.org \
--cc=kafai@fb.com \
--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).