netdev - Re: [PATCH 4/6] wl1251: Generate random MAC address only if driver does not have valid

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Date:   Sat, 24 Dec 2016 19:38:44 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Pavel Machek <pavel@....cz>
Cc:     Ming Lei <ming.lei@...onical.com>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        David Gnedt <david.gnedt@...izone.at>,
        Michal Kazior <michal.kazior@...to.com>,
        Daniel Wagner <wagi@...om.org>,
        Tony Lindgren <tony@...mide.com>,
        Sebastian Reichel <sre@...nel.org>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Grazvydas Ignotas <notasas@...il.com>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 4/6] wl1251: Generate random MAC address only if driver does not have valid

On Saturday 24 December 2016 19:08:54 Pavel Machek wrote:
> On Sat 2016-12-24 17:52:59, Pali Rohár wrote:
> > Before this patch driver generated random MAC address every time
> > when was doing initialization. And after that random MAC address
> > could be overwritten with fixed one if provided.
> 
> Before this patch, driver generated random MAC address every time it
> was initialized. After that random MAC address could be overwritten
> with fixed one, if provided.
> 
> > This patch changes order. First it tries to read fixed MAC address
> > and if it fails then driver generates random MAC address.
> 
> I don't quite get where the advantage is supposed to be. Is it that
> "use_eeprom" is set, but reading fails?

Random bytes are read from kernel only if random MAC address is needed. 
And in wl->mac_addr is always either invalid address or permanenent mac 
address which will be used. Without patch in wl->mac_addr can be random 
temporary address for some time...

> The only case where this helps is if wl1251_read_eeprom_mac()
> succeeds but reads invalid address.
> 
> > Signed-off-by: Pali Rohár <pali.rohar@...il.com>
> 
> Acked-by: Pavel Machek <pavel@....cz>

-- 
Pali Rohár
pali.rohar@...il.com

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