Re: WARNING at net/mac80211/sta_info.c:1057 (__sta_info_destroy_part2())

Johannes Berg [off-list ref] writes:

On Wed, 2019-09-11 at 21:19 +0300, Kalle Valo wrote:

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Looks like indeed the driver gives the device at least *3 seconds* for
every command, see ath10k_wmi_cmd_send(), so most likely this would
eventually have finished, but who knows how many firmware commands it
would still have attempted to send...

3 seconds is a bit short but in normal cases it should be enough. Of
course we could increase the delay but I'm skeptic it would help here.

I was thinking 3 seconds is way too long :-)

Heh :)

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Perhaps the driver should mark the device as dead and fail quickly once
it timed out once, or so, but I'll let Kalle comment on that.

Actually we do try to restart the device when a timeout happens in
ath10k_wmi_cmd_send():

        if (ret == -EAGAIN) {
                ath10k_warn(ar, "wmi command %d timeout, restarting hardware\n",
                            cmd_id);
                queue_work(ar->workqueue, &ar->restart_work);
        }

Yeah, and this is the problem, in a sense, I'd think. It seems to me
that at this point the code needs to tag the device as "dead" and
immediately return from any further commands submitted to it with an
error (e.g. -EIO).

Yeah, ath10k_core_restart() is supposed change to state
ATH10K_STATE_RESTARTING but very few mac80211 ops in ath10k_ops are
checking for it, and to me it looks like quite late even. I think a
proper fix for ops which can sleep is to check ar->state is
ATH10K_STATE_ON and for ops which cannot sleep check
ATH10K_FLAG_CRASH_FLUSH.

But of course this just fixes the symptoms, the root cause for timeouts
needs to be found as well.

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