On 2020-08-20 17:26, Krishna Chaitanya wrote:
On Thu, Aug 20, 2020 at 2:49 PM Krishna Chaitanya
<chaitanya.m...@gmail.com> wrote:

On Thu, Aug 20, 2020 at 2:03 PM Kalle Valo <kv...@codeaurora.org> wrote:
>
> Wen Gong <wg...@codeaurora.org> writes:
>
...
> 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/

Also, the most common cause for such issues (1st
napi_synchronize/napi_disable hang)
is that napi_poll is being scheduled, so, you might want to check that
napi_schedule isn't
called after stop.

cd ath10k; git log --grep=napi shows plenty of such issues. the one
that matches closest is
c2cac2f74ab4bcf0db0dcf3a612f1e5b52d145c8, so, it could just be a regression.
Also, I see that napi_schedule() is being called from work_queue async_work_rx so we should cancel that work in hif_stop before calling napi_synchronize.
Yes, I will do that in a new patch.

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