From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Patrick McHardy <kaber@trash.net>
Cc: netfilter-devel@vger.kernel.org
Subject: Re: [PATCH nf-next 1/3] netfilter: nf_tables: add generation mask to table objects
Date: Thu, 6 Aug 2015 12:21:05 +0200 [thread overview]
Message-ID: <20150806102105.GB18683@salvia> (raw)
In-Reply-To: <20150805084128.GB13187@acer.localdomain>
On Wed, Aug 05, 2015 at 10:41:28AM +0200, Patrick McHardy wrote:
> On 04.08, Pablo Neira Ayuso wrote:
> > On Tue, Aug 04, 2015 at 11:09:17AM +0200, Patrick McHardy wrote:
> > > On 04.08, Pablo Neira Ayuso wrote:
> > > > The dumping of table objects can be inconsistent when interfering with the
> > > > preparation phase of our 2-phase commit protocol because:
> > > >
> > > > 1) We remove objects from the lists during the preparation phase, that can be
> > > > added re-added from the abort step. Thus, we may miss objects that are still
> > > > active.
> > > >
> > > > 2) We add new objects to the lists during the preparation phase, so we may get
> > > > objects that are not yet active with an internal flag set.
> > > >
> > > > We can resolve this problem with generation masks, as we already do for rules
> > > > when we expose them to the packet path.
> > > >
> > > > After this change, we always obtain a consistent list as long as we stay in the
> > > > same generation. The userspace side can detect interferences through the
> > > > generation counter. If so, it needs to restart.
> > > >
> > > > As a result, we can get rid of the internal NFT_TABLE_INACTIVE flag.
> > >
> > > I have a similar patch queued up, however there seems to be something missing
> > > in this patch. The lookup functions need to take the genmask into account.
> > > Otherwise you can not delete and add a new table in the same batch. The same
> > > holds for all other object types.
> >
> > I got what you meant, we have to skip the delete table when iterating
> > over the list.
>
> Exactly. I'd propose to simply pass in the requested genid, this has the added
> benefit of not having to sprinkle those checks throughout the code.
If that simplifies the patchset, I think it's a good idea. Thanks!
prev parent reply other threads:[~2015-08-06 10:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-04 9:05 [PATCH nf-next 1/3] netfilter: nf_tables: add generation mask to table objects Pablo Neira Ayuso
2015-08-04 9:05 ` [PATCH nf-next 2/3] netfilter: nf_tables: add generation mask to chain objects Pablo Neira Ayuso
2015-08-04 9:05 ` [PATCH nf-next 3/3] netfilter: nf_tables: add generation mask to set objects Pablo Neira Ayuso
2015-08-04 9:12 ` Patrick McHardy
2015-08-04 9:29 ` Pablo Neira Ayuso
2015-08-04 10:38 ` Patrick McHardy
2015-08-04 17:23 ` Pablo Neira Ayuso
2015-08-04 9:09 ` [PATCH nf-next 1/3] netfilter: nf_tables: add generation mask to table objects Patrick McHardy
2015-08-04 9:29 ` Pablo Neira Ayuso
2015-08-04 10:26 ` Patrick McHardy
2015-08-04 17:04 ` Pablo Neira Ayuso
2015-08-05 9:09 ` Patrick McHardy
2015-08-06 10:20 ` Pablo Neira Ayuso
2015-08-08 15:53 ` Patrick McHardy
2015-08-10 7:56 ` Patrick McHardy
2015-08-10 18:37 ` Pablo Neira Ayuso
2015-08-04 18:21 ` Pablo Neira Ayuso
2015-08-05 8:41 ` Patrick McHardy
2015-08-06 10:21 ` Pablo Neira Ayuso [this message]
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