linux-kernel - Re: [PATCH v3 01/15] media: i2c: ds90ub9x3: Fix extra fwnode_handle

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Message-ID: <Z1a-CV02K_o4rMHU@kekkonen.localdomain>
Date: Mon, 9 Dec 2024 09:53:13 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hverkuil-cisco@...all.nl>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Jai Luthra <jai.luthra@...asonboard.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v3 01/15] media: i2c: ds90ub9x3: Fix extra
 fwnode_handle_put()

Moi,

On Mon, Dec 09, 2024 at 11:46:45AM +0200, Tomi Valkeinen wrote:
> Hi,
> 
> On 09/12/2024 11:09, Sakari Ailus wrote:
> > Huomenta,
> > 
> > On Wed, Dec 04, 2024 at 01:05:15PM +0200, Tomi Valkeinen wrote:
> > > The ub913 and ub953 drivers call fwnode_handle_put(priv->sd.fwnode) as
> > > part of their remove process, and if the driver is removed multiple
> > > times, eventually leads to put "overflow", possibly causing memory
> > 
> > This is, in fact, an extra put. It'll lead to underflow, not overflow.
> 
> Well, there are too many puts, so "put overflow" =). I don't think underflow
> is the right word here either, but it's probably better than overflow. Maybe
> I'll reword it so that it doesn't have a flow at all.

Sound good.

> 
> > I'd expect removing it once would be already too much.
> 
> True, but there's something keeping some refs to the fwnode even without
> these drivers (otherwise they'd be freed when these drivers are not around),
> so the issue shows only when those refs are taken out by the puts in these
> drivers.

Port nodes perhaps?

-- 
Terveisin,

Sakari Ailus