From: Johannes Berg <johannes@sipsolutions.net>
To: Ben Greear <greearb@candelatech.com>
Cc: Tejun Heo <tj@kernel.org>,
"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: ath5k/mac80211: Reproducible deadlock with 64-stations.
Date: Thu, 11 Nov 2010 18:37:07 -0800 [thread overview]
Message-ID: <1289529427.3695.9.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <4CDC8EED.60602@candelatech.com>
On Thu, 2010-11-11 at 16:48 -0800, Ben Greear wrote:
> I have a potential scenario:
>
> The ieee80211_do_stop logic is called under RTNL, and it
> then calls flush_work().
>
> What if the worker thread is currently blocked on something like
> wireless_nlevent_process which tries to acquire rtnl?
>
> Wouldn't that cause a deadlock?
Only if Tejun's deadlock avoidance doesn't work -- we used to have a
separate kernel thread for mac80211 work including sdata->work which
never acquired the RTNL. Also, we have lockdep annotations for exactly
this kind of thing ("events" and "(linkwatch_work).work" in your held
locks output) that should catch this.
johannes
next prev parent reply other threads:[~2010-11-12 2:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-10 23:02 ath5k/mac80211: Reproducible deadlock with 64-stations Ben Greear
2010-11-11 0:57 ` Ben Greear
2010-11-11 1:03 ` Johannes Berg
2010-11-11 5:51 ` Ben Greear
2010-11-11 1:02 ` Johannes Berg
2010-11-11 9:27 ` Tejun Heo
2010-11-11 16:55 ` Ben Greear
2010-11-11 18:26 ` Ben Greear
2010-11-11 23:12 ` Ben Greear
2010-11-12 10:11 ` Tejun Heo
2010-11-12 10:15 ` Tejun Heo
2010-11-12 18:06 ` Ben Greear
2010-11-12 18:13 ` Tejun Heo
2010-11-12 18:34 ` Ben Greear
2010-11-12 17:18 ` Ben Greear
2010-11-12 0:48 ` Ben Greear
2010-11-12 2:37 ` Johannes Berg [this message]
2010-11-12 16:32 ` Ben Greear
2010-11-12 16:45 ` Johannes Berg
2010-11-12 17:37 ` Ben Greear
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