From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH net 00/15] netpoll: avoid capture effects for NAPI drivers
Date: Mon, 24 Sep 2018 12:41:20 -0700
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References: <20180921222752.101307-1-edumazet@google.com> <20180923.220440.434897583339366571.davem@davemloft.net>
 <CANn89i+8mngtTLs8gzmEFjreW9ie64MPmZWaUDV+KRR7wgNfMA@mail.gmail.com> <B352B219-D053-432C-AEB7-C0A74D2F6613@fb.com>
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Cc: David Miller <davem@davemloft.net>,
        netdev <netdev@vger.kernel.org>, michael.chan@broadcom.com,
        Ariel Elior <ariel.elior@cavium.com>,
        Eric Dumazet <eric.dumazet@gmail.com>,
        Tariq Toukan <tariqt@mellanox.com>,
        Saeed Mahameed <saeedm@mellanox.com>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
        jakub.kicinski@netronome.com, Jay Vosburgh <j.vosburgh@gmail.com>,
        Veaceslav Falico <vfalico@gmail.com>,
        Andy Gospodarek <andy@greyhouse.net>
To: songliubraving@fb.com
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On Mon, Sep 24, 2018 at 12:31 PM Song Liu <songliubraving@fb.com> wrote:

> This triggers dev_watchdog() on a simple netperf TCP_RR on bnxt (I haven't
> tested other drivers yet).
>
> I guess this is because NAPI_STATE_SCHED is set when poll_one_napi() calls
> napi->poll(). And then cleared by napi->poll().

Which part of napi->poll() could possibly clear NAPI_STATE_SCHED when
called by netpoll ?

AFAIK, napi_complete_done() should exit early (before having a chance
to clear NAPI_STATE_SCHED)
because of :

if (unlikely(n->state & (NAPIF_STATE_NPSVC | NAPIF_STATE_IN_BUSY_POLL)))
     return false;

Thanks !