Linux-Wireless Archive on lore.kernel.org
 help / color / Atom feed
From: Johannes Berg <johannes@sipsolutions.net>
To: Kalle Valo <kvalo@codeaurora.org>
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 20:23:33 +0200
Message-ID: <383b145b608e0fe3a35ffb0ceb99fdf938d4e2bb.camel@sipsolutions.net> (raw)
In-Reply-To: <87ef0mlmqg.fsf@tynnyri.adurom.net>

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 :-)

> > 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). You can can actually see in the initial report that
while the restart was triggered, it too is waiting to acquire the RTNL:

>    Workqueue: events_freezable ieee80211_restart_work [mac80211]
>    Call Trace:
>     schedule+0x39/0xa0
>     schedule_preempt_disabled+0xa/0x10
>     __mutex_lock.isra.0+0x263/0x4b0
>     ieee80211_restart_work+0x54/0xe0 [mac80211]
>     process_one_work+0x1cf/0x370
>     worker_thread+0x4a/0x3c0
>     kthread+0xfb/0x130
>     ret_from_fork+0x35/0x40


So basically all this delay is mac80211 and the driver doing stuff with
the device, but every single thing has to time out and probably some
stuff loops etc., and then it just takes long enough with the RTNL held
that everything goes south.

johannes


  reply index

Thread overview: 12+ 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 [this message]
2019-09-11 18:48       ` Kalle Valo
2019-09-11 18:10 ` Kalle Valo

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=383b145b608e0fe3a35ffb0ceb99fdf938d4e2bb.camel@sipsolutions.net \
    --to=johannes@sipsolutions.net \
    --cc=ath10k@lists.infradead.org \
    --cc=davem@davemloft.net \
    --cc=kvalo@codeaurora.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-wireless@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Wireless Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-wireless/0 linux-wireless/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-wireless linux-wireless/ https://lore.kernel.org/linux-wireless \
		linux-wireless@vger.kernel.org linux-wireless@archiver.kernel.org
	public-inbox-index linux-wireless

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-wireless


AGPL code for this site: git clone https://public-inbox.org/ public-inbox