linux-kernel - Re: [PATCH v1] mod_devicetable: Bump auxiliary_device

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Message-ID: <aQilFRQYQVy-OEna@black.igk.intel.com>
Date: Mon, 3 Nov 2025 13:50:29 +0100
From: Raag Jadav <raag.jadav@...el.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Greg KH <gregkh@...uxfoundation.org>, kees@...nel.org,
	broonie@...nel.org, arnd@...db.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] mod_devicetable: Bump auxiliary_device_id name size

On Mon, Nov 03, 2025 at 10:16:58AM +0200, Andy Shevchenko wrote:
> On Sat, Nov 01, 2025 at 07:18:22AM +0100, Greg KH wrote:
> > On Sat, Nov 01, 2025 at 12:32:34AM +0530, Raag Jadav wrote:
> > > Since auxiliary device id string is formed using the combination of parent
> > > and child device names, it may require more than 32 bytes if both the names
> > > are long enough. Bump the size to 40 bytes to satisfy such cases.
> > 
> > What in-kernel users need such a larger name?  If we allow larger names,
> > people will try to do crazy things and use memory addresses in them (has
> > happened already...)
> > 
> > > Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > > Signed-off-by: Raag Jadav <raag.jadav@...el.com>
> > > ---
> > > Triggered by [1].
> > > 
> > > [1] https://lore.kernel.org/r/aQSwWLVKH_3TthTW@smile.fi.intel.com
> > 
> > How long would this driver submission's name be?  I couldn't figure it
> > out, and really, any device with a huge name is going to be a pain...
> 
> Right, Raag, please describe a use case.

The driver linked above compiles to intel_ehl_pse_io, so the child will
match against "intel_ehl_pse_io.gpio-elkhartlake" which is 34 bytes
(including termination).

Would that be sufficient or did I miss something?

Raag