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From: Michael Lilja <michael.lilja@gmail.com>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	Florian Westphal <fw@strlen.de>,
	netdev@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org,
	coreteam@netfilter.org
Subject: Re: [PATCH] Periodically flow expire from flow offload tables
Date: Wed, 26 Oct 2022 21:40:11 +0200	[thread overview]
Message-ID: <03E5D5FA-5A0D-4E5A-BA32-3FE51764C02E@gmail.com> (raw)
In-Reply-To: <25246B91-B5BE-43CA-9D98-67950F17F0A1@gmail.com>

Hi,

I just quickly tried following the flow_offload_teardown() path instead of clearing IPS_OFFLOAD in flow_offload_del() and it does have some side effects. The flow is added again before the HW has actually reported it to be NF_FLOW_HW_DEAD. 

The sequence with my patch is:
  : Retire -> Remove from hw tables -> Remove from sw tables -> kfree(flow) -> flow_offload_add()

But if flow_offload_teardown() is called on expire I see:
  : Retire -> Remove from hw tables -> flow_offload_add() -> Remove from sw tables -> kfree(flow)
 
I need to investigate why this happens, maybe the IPS_OFFLOAD flag is cleared too early and should not be cleared until the flow is actually removed, like I do? Maybe the issue is not seen before because on timeout or flow_is_dying() no packet arrive to create the flow again prematurely?

Thanks,
Michael


  reply	other threads:[~2022-10-26 19:40 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-23 17:16 [PATCH] Periodically flow expire from flow offload tables Michael Lilja
2022-10-25 11:05 ` Pablo Neira Ayuso
2022-10-25 12:36   ` Michael Lilja
2022-10-25 13:00     ` Pablo Neira Ayuso
2022-10-25 13:32       ` Michael Lilja
2022-10-26 10:50         ` Pablo Neira Ayuso
2022-10-26 17:36           ` Michael Lilja
2022-10-26 19:40             ` Michael Lilja [this message]
2022-11-02 18:52               ` Pablo Neira Ayuso
2022-11-02 19:52                 ` Michael Lilja

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