Re: [PATCH net 00/15] netpoll: avoid capture effects for NAPI drivers

[Song Liu]

> On Sep 24, 2018, at 12:41 PM, Eric Dumazet <eduma...@google.com> wrote:
> 
> On Mon, Sep 24, 2018 at 12:31 PM Song Liu <songliubrav...@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 !

You are right on this condition. But this does trigger dev_watchdog() for
some reason. 

Thanks,
Song