From: Helmut Schaa <helmut.schaa@googlemail.com>
To: Ivo Van Doorn <ivdoorn@gmail.com>
Subject: Re: BUG in rt2x00lib_txdone() with 2.6.37-rc8
Date: Sun, 16 Jan 2011 02:59:14 +0100
Cc: Ingo Brunberg <ingo_brunberg@web.de>, linux-kernel@vger.kernel.org,
	linux-wireless@vger.kernel.org
References: <m31v4hkmkf.fsf@ingo.homenetwork> <201101131423.51640.helmut.schaa@googlemail.com> <AANLkTimMVdsGONSD9OmnX2eJk51H5Pzj4K8irHa=E-qx@mail.gmail.com>
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Am Samstag, 15. Januar 2011 schrieb Ivo Van Doorn:
> Hi,
> 
> > Just a shot in the dark but since the stack trace shows the newly added
> > watchdog this might be the result of a race between a regular txdone work
> > (mac80211 workqueue) vs the watchdog work (global workqueue).
> >
> > I guess the following situation could happen:
> > A regular tx done work calls rt2x00lib_txdone which first sets entry->skb to
> > NULL, calls the driver specific clear_entry and afterwards increases
> > Q_INDEX_DONE. If the watchdog work calls rt2x00lib_txdone on a different CPU
> > inbetween the skb might be NULL and cause the above oops.
> 
> This could be, would be interesting to know if compat-wireless also shows
> this problem. Because the queue refactoring code which should have solved
> these race conditions was added after 2.6.37.

I also guess that this issue would be fixed in compat-wireless due to the queue
refactoring. But I guess that is way too big for a stable kernel :(

Helmut