Subject: Race in ieee80211_register_hw()
From: Maxime Bizon <mbizon@freebox.fr>
Reply-To: mbizon@freebox.fr
To: linux-wireless@vger.kernel.org
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Date: Mon, 19 Dec 2011 18:04:08 +0100
Message-ID: <1324314248.6069.112.camel@sakura.staff.proxad.net> (sfid-20111219_180500_295801_20E8D326)
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Sender: linux-wireless-owner@vger.kernel.org


Hi all,

I'm using udev/sysfs to detect when a new phy becomes available, and
then immediately open it.

When I insmod the wifi card module driver, it works most of the times,
but sometimes I get this:

ieee80211 phy0: Failed to initialize rate control algorithm


I noticed that ieee80211_register_hw() first registers the PHY, which
makes it available to userspace, then does subsequent config calls on
it. ieee80211_init_rate_ctrl_alg then fails since local->open_count is
not zero.

This is easy to reproduce by adding an msleep() after wiphy_register()

What lock should I use to surround the whole registration process ?

-- 
Maxime