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Subject: Re: [PATCH] cfg80211: Purge frame registrations on iftype change
To:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org
Cc:     stable@vger.kernel.org
References: <20190828211110.15005-1-denkenz@gmail.com>
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 <ea9a895d18a34b876c440e6272b1d55d27c8a419.camel@sipsolutions.net>
From:   Denis Kenzior <denkenz@gmail.com>
Message-ID: <8fdb9d1f-d535-22ed-1a1a-357f826ecf54@gmail.com>
Date:   Wed, 11 Sep 2019 07:12:42 -0500
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Hi Johannes,

>> 'typical' failure paths.  I didn't add such checking in the other patch
>> set since I felt you might find it overly intrusive on userspace.  But
>> maybe we really should do this?
> 
> As I just said on the other patch, I think we probably should do that
> there, if just to be able to advertise a correct set of interface types
> that you can switch between there. I don't see how it'd be more
> intrusive to userspace than failing later? :-)

What I was worried about was that all the fullmac drivers would have had 
to be updated to set the feature bit, and it would have caused 
wpa_s/hostapd to no longer be able to do the whole set_iftype -> ebusy 
-> ifdown & set_iftype retry logic until all were updated.

>> I would concur as that is what happens today.  But should it?
> 
> Well, dunno, what should happen? If you ask drivers they might want to
> remove & re-register after, for those registrations that are still
> possible.
> 

I would think you'd want to define a clear order of operations that 
cfg80211 / mac80211 would enforce :)

> 
> Let's not then.
> 
> I've applied this patch now.
> 

Great, thanks.

Regards,
-Denis