From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Paul Blakey <paulb@mellanox.com>
Cc: Oz Shlomo <ozsh@mellanox.com>, Roi Dayan <roid@mellanox.com>,
netdev@vger.kernel.org, Saeed Mahameed <saeedm@mellanox.com>,
netfilter-devel@vger.kernel.org
Subject: Re: [PATCH net] netfilter: flowtable: Fix expired flow not being deleted from software
Date: Mon, 11 May 2020 10:42:43 +0200 [thread overview]
Message-ID: <20200511084243.GA18188@salvia> (raw)
In-Reply-To: <a420c22a-9d52-c314-cf9b-ee19831e15a7@mellanox.com>
[-- Attachment #1: Type: text/plain, Size: 1346 bytes --]
On Mon, May 11, 2020 at 10:24:44AM +0300, Paul Blakey wrote:
>
>
> On 5/11/2020 1:26 AM, Pablo Neira Ayuso wrote:
> > On Wed, May 06, 2020 at 02:27:29PM +0300, Paul Blakey wrote:
> >> Once a flow is considered expired, it is marked as DYING, and
> >> scheduled a delete from hardware. The flow will be deleted from
> >> software, in the next gc_step after hardware deletes the flow
> >> (and flow is marked DEAD). Till that happens, the flow's timeout
> >> might be updated from a previous scheduled stats, or software packets
> >> (refresh). This will cause the gc_step to no longer consider the flow
> >> expired, and it will not be deleted from software.
> >>
> >> Fix that by looking at the DYING flag as in deciding
> >> a flow should be deleted from software.
> > Would this work for you?
> >
> > The idea is to skip the refresh if this has already expired.
> >
> > Thanks.
>
> The idea is ok, but timeout check + update isn't atomic (need atomic_inc_unlesss
> or something like that), and there is also
> the hardware stats which if comes too late (after gc finds it expired) might
> bring a flow back to life.
Right. Once the entry has expired, there should not be a way turning
back.
I'm attaching a new sketch, it's basically using the teardown state to
specify that the gc already made the decision to remove this entry.
Thanks.
[-- Attachment #2: x.patch --]
[-- Type: text/x-diff, Size: 1046 bytes --]
diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index 4344e572b7f9..42da6e337276 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -284,7 +284,7 @@ static void flow_offload_del(struct nf_flowtable *flow_table,
if (nf_flow_has_expired(flow))
flow_offload_fixup_ct(flow->ct);
- else if (test_bit(NF_FLOW_TEARDOWN, &flow->flags))
+ else
flow_offload_fixup_ct_timeout(flow->ct);
flow_offload_free(flow);
@@ -361,8 +361,10 @@ static void nf_flow_offload_gc_step(struct flow_offload *flow, void *data)
{
struct nf_flowtable *flow_table = data;
- if (nf_flow_has_expired(flow) || nf_ct_is_dying(flow->ct) ||
- test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
+ if (nf_flow_has_expired(flow) || nf_ct_is_dying(flow->ct))
+ set_bit(NF_FLOW_TEARDOWN, &flow->flags);
+
+ if (test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
if (test_bit(NF_FLOW_HW, &flow->flags)) {
if (!test_bit(NF_FLOW_HW_DYING, &flow->flags))
nf_flow_offload_del(flow_table, flow);
next prev parent reply other threads:[~2020-05-11 8:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-06 11:27 [PATCH net] netfilter: flowtable: Fix expired flow not being deleted from software Paul Blakey
2020-05-10 22:26 ` Pablo Neira Ayuso
2020-05-11 7:24 ` Paul Blakey
2020-05-11 8:42 ` Pablo Neira Ayuso [this message]
2020-05-11 9:50 ` Paul Blakey
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=20200511084243.GA18188@salvia \
--to=pablo@netfilter.org \
--cc=netdev@vger.kernel.org \
--cc=netfilter-devel@vger.kernel.org \
--cc=ozsh@mellanox.com \
--cc=paulb@mellanox.com \
--cc=roid@mellanox.com \
--cc=saeedm@mellanox.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).