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Date:   Wed, 26 Oct 2022 21:40:11 +0200
From:   Michael Lilja <>
To:     Pablo Neira Ayuso <>
Cc:     "David S. Miller" <>,
        Eric Dumazet <>,
        Jakub Kicinski <>,
        Paolo Abeni <>,
        Jonathan Corbet <>,
        Jozsef Kadlecsik <>,
        Florian Westphal <>,,,,,
Subject: Re: [PATCH] Periodically flow expire from flow offload tables


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?


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