netdev - Re: assert_cfg80211_lock warning with Linux v3.5-8833-g2d53492

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Message-ID: <20120801175628.GD22963@thinkpad-t410>
Date:	Wed, 1 Aug 2012 12:56:28 -0500
From:	Seth Forshee <seth.forshee@...onical.com>
To:	Johannes Berg <johannes@...solutions.net>,
	"John W. Linville" <linville@...driver.com>
Cc:	Arend van Spriel <arend@...adcom.com>,
	Josh Boyer <jwboyer@...hat.com>,
	Brett Rudley <brudley@...adcom.com>,
	Roland Vossen <rvossen@...adcom.com>,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: assert_cfg80211_lock warning with Linux v3.5-8833-g2d53492

On Wed, Aug 01, 2012 at 07:14:45PM +0200, Johannes Berg wrote:
> On Wed, 2012-08-01 at 11:19 -0500, Seth Forshee wrote:
> > On Wed, Aug 01, 2012 at 05:53:58PM +0200, Johannes Berg wrote:
> > > On Wed, 2012-08-01 at 17:51 +0200, Arend van Spriel wrote:
> > > > On 08/01/2012 05:38 PM, Arend van Spriel wrote:
> > > > >> brcmsmac needs to hold cfg80211_mutex before calling freq_reg_info...
> > > > >> > 
> > > > >> > It looks like those calls were added in mid-June.
> > > > >> > 
> > > > > I think mid-june sounds about right. We never observed the warning when
> > > > > changes to use regulatory infrastructure were tested/reviewed. Should
> > > > > this precondition be mentioned in cfg80211.h?
> > > > > 
> > > > > Gr. AvS
> > > > 
> > > > Diving in further it seems brcmsmac can not grab the cfg80211_mutex. So
> > > > another solution is needed.
> > > 
> > > Yeah I was going to say -- how can it possibly access that? It seems
> > > that in some patch the API got broken, it should be taking the lock or
> > > whatever ... I'll leave it to Luis to sort out though :-P
> > 
> > In other drivers freq_reg_info only seems to get used by the regulatory
> > notifiers, which get called with the lock held. brcmsmac is wanting to
> > know whether or not OFDM is allowed when setting the channel though, and
> > I didn't find that information anywhere outside the regulatory
> > information. If there's another way then calling freq_reg_info() could
> > be avoided. Or maybe we could add an OFDM flag to the channel
> > information?
> 
> Seems reasonable to add the flags (or some of them) to the channel
> flags, yeah.

Great, I'll work something up.

Seth
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