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Subject: Re: [PATCH 2/3] mac80211: use csa counter offsets instead of
 csa_active
From: Johannes Berg <johannes@sipsolutions.net>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless@vger.kernel.org
Date: Thu, 22 May 2014 15:45:56 +0200
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On Thu, 2014-05-22 at 15:28 +0200, Michal Kazior wrote:
> vif->csa_active is protected by mutexes only. This
> means it is unreliable to depend on it on codeflow
> in non-sleepable beacon and CSA code. There was no
> guarantee to have vif->csa_active update be
> visible before beacons are updated on SMP systems.
> 
> Using csa counter offsets which are embedded in
> beacon struct (and thus are protected with single
> RCU assignment) is much safer.

This seems reasonable, but many uses of csa_active remain, no? hwsim for
example seems to access it without locking as well.

johannes