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Message-ID: <6c865a0d04d28e9378acf75ae7646b9bb432b189.camel@sipsolutions.net>
Subject: Re: [PATCH] cfg80211: fix race in netlink owner interface
 destruction
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Kalle Valo <kvalo@kernel.org>
Cc:     linux-wireless@vger.kernel.org,
        Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= <toke@redhat.com>
Date:   Tue, 01 Feb 2022 15:36:22 +0100
In-Reply-To: <871r0md58n.fsf@tynnyri.adurom.net>
References: <20220201130951.22093-1-johannes@sipsolutions.net>
         <871r0md58n.fsf@tynnyri.adurom.net>
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On Tue, 2022-02-01 at 16:35 +0200, Kalle Valo wrote:
> Johannes Berg <johannes@sipsolutions.net> writes:
> 
> > From: Johannes Berg <johannes.berg@intel.com>
> > 
> > My previous fix here to fix the deadlock left a race where
> > the exact same deadlock (see the original commit referenced
> > below) can still happen if cfg80211_destroy_ifaces() already
> > runs while nl80211_netlink_notify() is still marking some
> > interfaces as nl_owner_dead.
> > 
> > The race happens because we have two loops here - first we
> > dev_close() all the netdevs, and then we destroy them. If we
> > also have two netdevs (first one need only be a wdev though)
> > then we can find one during the first iteration, close it,
> > and go to the second iteration -- but then find two, and try
> > to destroy also the one we didn't close yet.
> > 
> > Fix this by only iterating once.
> > 
> > Change-Id: Ie56cd0ef3f0d2108bb8a25c8bb5efced15e6a909
> 
> You forgot the Change-Id.
> 
Wtf, sorry, guess I sent it from a place with the wrong script. I'll
strip it when I apply it, I guess

johannes