From: Florian Westphal <fw@strlen.de>
To: David Miller <davem@davemloft.net>
Cc: fw@strlen.de, john.hurley@netronome.com, netdev@vger.kernel.org,
simon.horman@netronome.com, jakub.kicinski@netronome.com,
jhs@mojatatu.com, oss-drivers@netronome.com
Subject: Re: [RFC net-next v2 1/1] net: sched: protect against loops in TC filter hooks
Date: Thu, 6 Jun 2019 21:52:55 +0200 [thread overview]
Message-ID: <20190606195255.4uelltuxptwobhiv@breakpoint.cc> (raw)
In-Reply-To: <20190606.111954.2036000288766363267.davem@davemloft.net>
David Miller <davem@davemloft.net> wrote:
> From: Florian Westphal <fw@strlen.de>
> Date: Thu, 6 Jun 2019 14:58:18 +0200
>
> >> @@ -827,6 +828,7 @@ struct sk_buff {
> >> __u8 tc_at_ingress:1;
> >> __u8 tc_redirected:1;
> >> __u8 tc_from_ingress:1;
> >> + __u8 tc_hop_count:2;
> >
> > I dislike this, why can't we just use a pcpu counter?
>
> I understand that it's because the only precise context is per-SKB not
> per-cpu doing packet processing. This has been discussed before.
I don't think its worth it, and it won't work with physical-world
loops (e.g. a bridge setup with no spanning tree and a closed loop).
Also I fear that if we start to do this for tc, we will also have to
followup later with more l2 hopcounts for other users, e.g. veth,
bridge, ovs, and so on.
next prev parent reply other threads:[~2019-06-06 19:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-06 12:49 [RFC net-next v2 1/1] net: sched: protect against loops in TC filter hooks John Hurley
2019-06-06 12:58 ` Florian Westphal
2019-06-06 13:27 ` John Hurley
2019-06-06 14:04 ` Florian Westphal
2019-06-06 18:19 ` David Miller
2019-06-06 19:52 ` Florian Westphal [this message]
2019-06-11 14:58 ` John Hurley
2019-06-11 15:03 ` Florian Westphal
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=20190606195255.4uelltuxptwobhiv@breakpoint.cc \
--to=fw@strlen.de \
--cc=davem@davemloft.net \
--cc=jakub.kicinski@netronome.com \
--cc=jhs@mojatatu.com \
--cc=john.hurley@netronome.com \
--cc=netdev@vger.kernel.org \
--cc=oss-drivers@netronome.com \
--cc=simon.horman@netronome.com \
/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).