Re: [PATCH 3/5] media: sunxi: Add A10 CSI driver

From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>,
	Hans Verkuil <hans.verkuil@cisco.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	linux-media@vger.kernel.org, Andrzej Hajda <a.hajda@samsung.com>,
	Chen-Yu Tsai <wens@csie.org>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	Mark Rutland <mark.rutland@arm.com>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>
Subject: Re: [PATCH 3/5] media: sunxi: Add A10 CSI driver
Date: Thu, 22 Nov 2018 00:01:03 +0200	[thread overview]
Message-ID: <20181121220102.6nn7uwu2c67zs6pz@mara.localdomain> (raw)
In-Reply-To: <20181115205106.thbkojnzdwmaeui3@flea>

On Thu, Nov 15, 2018 at 09:51:06PM +0100, Maxime Ripard wrote:
> Hi Hans,
> 
> Thanks for your review! I'll address the other comments you made.
> 
> On Tue, Nov 13, 2018 at 01:24:47PM +0100, Hans Verkuil wrote:
> > > +static int csi_probe(struct platform_device *pdev)
> > > +{
> > > +	struct sun4i_csi *csi;
> > > +	struct resource *res;
> > > +	int ret;
> > > +	int irq;
> > > +
> > > +	csi = devm_kzalloc(&pdev->dev, sizeof(*csi), GFP_KERNEL);
> > 
> > devm_kzalloc is not recommended: all devm_ memory is freed when the driver
> > is unbound, but a filehandle might still have a reference open.
> 
> How would a !devm variant with a kfree in the remove help? We would
> still fall in the same case, right?

Not quite. For video nodes this is handled: the release callback gets called
once there are no file handles open to the device. That may well be much
later than the device has been unbound from the driver.

-- 
Sakari Ailus
sakari.ailus@linux.intel.com