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Subject: Re: [PATCH] mac80211: fix race in ieee80211_register_hw()
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Krishna Chaitanya <chaitanya.mgit@gmail.com>
Cc:     Kalle Valo <kvalo@codeaurora.org>,
        Sumit Garg <sumit.garg@linaro.org>,
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        Daniel Thompson <daniel.thompson@linaro.org>,
        Loic Poulain <loic.poulain@linaro.org>, stable@vger.kernel.org
Date:   Mon, 06 Apr 2020 17:06:19 +0200
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On Mon, 2020-04-06 at 19:55 +0530, Krishna Chaitanya wrote:

> > iw phy0 interface add wlan0 type station
> > ip link set wlan0 up
> Ah okay, got it, thanks. Very narrow window though :-) as the
> alloc_ordered_workqueue
> doesn't need RTNL and there is a long way to go to do if_add() from
> user and setup
> the driver for interrupts. 

True, I do wonder how this is hit. Maybe something with no preempt and a
uevent triggering things?

> Again depends on the driver though, it
> should properly handle
> pending ieee80211_register_hw() with start().

It could, but it'd be really tricky. Much better to fix mac80211.

johannes