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From:   "Dedy Lansky" <dlansky@codeaurora.org>
To:     "'Johannes Berg'" <johannes@sipsolutions.net>,
        <linux-wireless@vger.kernel.org>
Cc:     "'Florian Westphal'" <fw@strlen.de>,
        "'Johannes Berg'" <johannes.berg@intel.com>
References: <20190731220848.1045-1-johannes@sipsolutions.net>
In-Reply-To: <20190731220848.1045-1-johannes@sipsolutions.net>
Subject: RE: [EXT] [RFC/RFT] cfg80211: decouple us from the RTNL
Date:   Mon, 5 Aug 2019 18:20:05 +0300
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From: linux-wireless-owner@vger.kernel.org
<linux-wireless-owner@vger.kernel.org> On Behalf Of Johannes Berg
Sent: Thursday, August 1, 2019 1:09 AM

> Fix that by re-adding a mutex to each wiphy/rdev as we had at
> some point, so we have locking for the wireless_dev lists and
> all the other things in there, and also so that drivers still
> don't have to worry too much about it (they still won't get
> parallel calls for a single device).

Sounds good.

> Then, we can restrict the RTNL to a few cases where we add or
> remove interfaces and really need the added protection. Some
> of the global list management still also uses the RTNL, since
> we need to have it anyway for netdev management.

> TODO:
>  - use wiphy_lock()/wiphy_unlock() in all drivers as the code
>    changed in mac80211 does

I guess this change breaks existing drivers because some drivers assume RTNL
is locked when their cfg callbacks are executed. Is that correct?

Would there be any simple rules for drivers when to use each one of the
locking API: rtnl vs wiphy vs wdev ?

Thanks,
 Dedy.