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From: Kalle Valo <kvalo@codeaurora.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	linux-wireless@vger.kernel.org, Netdev <netdev@vger.kernel.org>,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	ath10k@lists.infradead.org
Subject: Re: WARNING at net/mac80211/sta_info.c:1057 (__sta_info_destroy_part2())
Date: Wed, 11 Sep 2019 21:48:09 +0300
Message-ID: <87zhjak6ty.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <383b145b608e0fe3a35ffb0ceb99fdf938d4e2bb.camel@sipsolutions.net> (Johannes Berg's message of "Wed, 11 Sep 2019 20:23:33 +0200")

Johannes Berg <johannes@sipsolutions.net> writes:

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

>> > 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.

-- 
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

  reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-11 10:05 Linus Torvalds
2019-09-11 10:26 ` Johannes Berg
2019-09-11 11:58   ` Linus Torvalds
2019-09-11 12:04     ` Johannes Berg
2019-09-11 13:03       ` Ben Greear
2019-09-11 13:21         ` Linus Torvalds
2019-09-11 13:31           ` Ben Greear
2019-09-11 13:32       ` Kalle Valo
2019-09-11 18:19   ` Kalle Valo
2019-09-11 18:23     ` Johannes Berg
2019-09-11 18:48       ` Kalle Valo [this message]
2019-09-11 18:10 ` Kalle Valo
2019-10-20 15:12   ` Tomislav Požega
2019-10-21 14:01     ` Ben Greear

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