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From:   Krishna Chaitanya <chaitanya.mgit@gmail.com>
Date:   Thu, 20 Aug 2020 21:38:41 +0530
Message-ID: <CABPxzYLu_81h+aWWeNKRyH=CJ=+waB3zmT41BTZ9Mo733PqErQ@mail.gmail.com>
Subject: Re: [RFC] ath10k: change to do napi_enable and napi_disable when
 insmod and rmmod for sdio
To:     Wen Gong <wgong@codeaurora.org>
Cc:     Kalle Valo <kvalo@codeaurora.org>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        ath10k <ath10k@lists.infradead.org>
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On Thu, Aug 20, 2020 at 8:07 PM Wen Gong <wgong@codeaurora.org> wrote:
>
> On 2020-08-20 18:52, Krishna Chaitanya wrote:
> > On Thu, Aug 20, 2020 at 3:45 PM Wen Gong <wgong@codeaurora.org> wrote:
> >>
> >> On 2020-08-20 17:19, Krishna Chaitanya wrote:
> ...
> >> >> I'm not really convinced that this is the right fix, but I'm no NAPI
> >> >> expert. Can anyone else help?
> >> > Calling napi_disable() twice can lead to hangs, but moving NAPI from
> >> > start/stop to
> >> > the probe isn't the right approach as the datapath is tied to
> >> > start/stop.
> >> >
> >> > Maybe check the state of NAPI before disable?
> >> >
> >> >  if (test_bit(NAPI_STATE_SCHED, &ar->napi.napi.state))
> >> >   napi_disable(&ar->napi)
> >> > or maintain napi_state like this
> >> > https://patchwork.kernel.org/patch/10249365/
> >> it is better to use above link's patch.
> >> napi.state is controlled by napi API, it is better ath10k not know it.
> > Sure, but IMHO just canceling the async rx work should solve the issue.
> Oh no, canceling the async rx work will not solve this issue, rx worker
> ath10k_rx_indication_async_work call napi_schedule, after napi_complete,
> the NAPI_STATE_SCHED will clear.
> The issue of this patch is because 2 thread called to hif_stop and
> NAPI_STATE_SCHED not clear.
That fix is still valid and good to have.

ndev_stop being called twice is typical scenarios (stop vs rmmod), so
 just checking the netdev_flags for IFF_UP and returning from hif_Stop
should suffice, no?