Subject: Re: [PATCH v2] cfg80211: fix race between sysfs and cfg80211
From: Johannes Berg <johannes@sipsolutions.net>
To: mbizon@freebox.fr
Cc: linux-wireless@vger.kernel.org
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Date: Mon, 16 Aug 2010 11:06:54 +0200
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On Sat, 2010-08-14 at 08:31 +0200, Maxime Bizon wrote:

> The driver is still inside ieee80211_register_hw(), but the userspace is
> able to create the AP interface before the call is over. Once
> wiphy_register() is done, no lock seems to prevent this from happening.
> 
> ieee80211_init_rate_ctrl_alg() then fails with EBUSY, and
> ieee80211_register_hw() starts unregistering the phy.
> 
> Is that expected ?

Oops. No, not really, but I think the problem is that we do
wiphy_register far too early. I think we should see if we can reorder
the code in register_hw(). It won't be perfect wrt. debugfs, but I don't
think that is a problem.

johannes