netdev - Re: [PATCHv2 net] usbnet: modern method to get random MAC

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Message-ID: <CANn89iJn_irj15UBeKZja7k9ViLGTxL3+fkgCERoAS2NM1hOZg@mail.gmail.com>
Date: Tue, 15 Oct 2024 09:59:15 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: Oliver Neukum <oneukum@...e.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, 
	netdev@...r.kernel.org, linux-usb@...r.kernel.org, 
	linux-kernel@...r.kernel.org, stable@...nel.org, 
	John Sperbeck <jsperbeck@...gle.com>, Brian Vazquez <brianvv@...gle.com>
Subject: Re: [PATCHv2 net] usbnet: modern method to get random MAC

On Tue, Oct 15, 2024 at 9:49 AM Oliver Neukum <oneukum@...e.com> wrote:
>
>
>
> On 15.10.24 01:00, Eric Dumazet wrote:
> > On Tue, Oct 15, 2024 at 12:24 AM Oliver Neukum <oneukum@...e.com> wrote:
> >>
> >> On 14.10.24 21:59, Eric Dumazet wrote:
> >>
> >>> As diagnosed by John Sperbeck :
> >>>
> >>> This patch implies all ->bind() method took care of populating net->dev_addr ?
> >>>
> >>> Otherwise the following existing heuristic is no longer working
> >>>
> >>> // heuristic:  "usb%d" for links we know are two-host,
> >>> // else "eth%d" when there's reasonable doubt.  userspace
> >>> // can rename the link if it knows better.
> >>> if ((dev->driver_info->flags & FLAG_ETHER) != 0 &&
> >>>       ((dev->driver_info->flags & FLAG_POINTTOPOINT) == 0 ||
> >>>        (net->dev_addr [0] & 0x02) == 0))
> >>> strscpy(net->name, "eth%d", sizeof(net->name));
> >>>
> >>
> >> Hi,
> >>
> >> you need to have a MAC to be an ethernet device, don't you?
> >
> > Before or after your patch, there was/is a MAC address, eventually random.
> >
> > The problem is about the test, which is now done while dev->dev_addr
> > is full of zeroes, which is not a valid address,
> > as shown by :
>
> Hi,
>
> I am sorry I misunderstood you. Yes, I overlooked the test for whether
> the MAC has been altered. I am preparing a patch. Could you give me
> John Perbeck's address, so I can include him in "reported-by"?
>

Reported-by: Greg Thelen <gthelen@...gle.com>
Diagnosed-by: John Sperbeck <jsperbeck@...gle.com>

Thank you.