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From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Sakari Ailus <sakari.ailus@linux.intel.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 14:58:53 +0100	[thread overview]
Message-ID: <20181122135853.4rpxb32d6ios5zac@flea> (raw)
In-Reply-To: <20181121220102.6nn7uwu2c67zs6pz@mara.localdomain>

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Hi Sakari,

On Thu, Nov 22, 2018 at 12:01:03AM +0200, Sakari Ailus wrote:
> 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.

I might be missing something, but how the release callback will be
able to get the reference to the structure we allocated here so that
it can free it?

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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WARNING: multiple messages have this Message-ID (diff)
From: maxime.ripard@bootlin.com (Maxime Ripard)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/5] media: sunxi: Add A10 CSI driver
Date: Thu, 22 Nov 2018 14:58:53 +0100	[thread overview]
Message-ID: <20181122135853.4rpxb32d6ios5zac@flea> (raw)
In-Reply-To: <20181121220102.6nn7uwu2c67zs6pz@mara.localdomain>

Hi Sakari,

On Thu, Nov 22, 2018 at 12:01:03AM +0200, Sakari Ailus wrote:
> 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.

I might be missing something, but how the release callback will be
able to get the reference to the structure we allocated here so that
it can free it?

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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  reply	other threads:[~2018-11-22 13:59 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-13  8:24 [PATCH 0/5] media: Allwinner A10 CSI support Maxime Ripard
2018-11-13  8:24 ` Maxime Ripard
2018-11-13  8:24 ` [PATCH 1/5] dt-bindings: media: Add Allwinner A10 CSI binding Maxime Ripard
2018-11-13  8:24   ` Maxime Ripard
2018-11-13  8:24   ` Maxime Ripard
2018-11-13  8:38   ` Sakari Ailus
2018-11-13  8:38     ` Sakari Ailus
2018-11-15 19:04     ` Maxime Ripard
2018-11-15 19:04       ` Maxime Ripard
2018-11-21 21:56       ` Sakari Ailus
2018-11-21 21:56         ` Sakari Ailus
2018-11-27 15:04         ` Maxime Ripard
2018-11-27 15:04           ` Maxime Ripard
2018-11-13 10:34   ` Sakari Ailus
2018-11-13 10:34     ` Sakari Ailus
2018-11-13  8:24 ` [PATCH 2/5] media: sunxi: Refactor the Makefile and Kconfig Maxime Ripard
2018-11-13  8:24   ` Maxime Ripard
2018-11-13  8:24 ` [PATCH 3/5] media: sunxi: Add A10 CSI driver Maxime Ripard
2018-11-13  8:24   ` Maxime Ripard
2018-11-13  8:57   ` Sakari Ailus
2018-11-13  8:57     ` Sakari Ailus
2018-11-13 12:24   ` Hans Verkuil
2018-11-13 12:24     ` Hans Verkuil
2018-11-13 15:19     ` Joe Perches
2018-11-13 15:19       ` Joe Perches
2018-11-13 15:39       ` Hans Verkuil
2018-11-13 15:39         ` Hans Verkuil
2018-11-15 20:51     ` Maxime Ripard
2018-11-15 20:51       ` Maxime Ripard
2018-11-21 22:01       ` Sakari Ailus
2018-11-21 22:01         ` Sakari Ailus
2018-11-22 13:58         ` Maxime Ripard [this message]
2018-11-22 13:58           ` Maxime Ripard
2018-11-13 12:48   ` Fabio Estevam
2018-11-13 12:48     ` Fabio Estevam
2018-11-13 12:48     ` Fabio Estevam
2018-11-13 13:37     ` Hans Verkuil
2018-11-13 13:37       ` Hans Verkuil
2018-11-13 13:37       ` Hans Verkuil
2018-11-13 14:13       ` Fabio Estevam
2018-11-13 14:13         ` Fabio Estevam
2018-11-13 14:13         ` Fabio Estevam
2018-11-13 14:46         ` Thomas Petazzoni
2018-11-13 14:46           ` Thomas Petazzoni
2018-11-13 14:46           ` Thomas Petazzoni
2018-11-13  8:24 ` [PATCH 4/5] ARM: dts: sun7i: Add CSI0 controller Maxime Ripard
2018-11-13  8:24   ` Maxime Ripard
2018-11-13  8:24 ` [PATCH 5/5] DO NOT MERGE: ARM: dts: bananapi: Add Camera support Maxime Ripard
2018-11-13  8:24   ` Maxime Ripard
2018-11-27  6:56   ` Jagan Teki
2018-11-27  6:56     ` Jagan Teki
2018-11-27 10:31     ` Maxime Ripard
2018-11-27 10:31       ` Maxime Ripard
2018-11-27 11:00       ` Jagan Teki
2018-11-27 11:00         ` Jagan Teki
2018-11-27 15:19         ` Maxime Ripard
2018-11-27 15:19           ` Maxime Ripard
2018-11-27 15:34           ` Jagan Teki
2018-11-27 15:34             ` Jagan Teki
2018-11-13 12:30 ` [PATCH 0/5] media: Allwinner A10 CSI support Hans Verkuil
2018-11-13 12:30   ` Hans Verkuil
2018-11-13 13:52   ` Maxime Ripard
2018-11-13 13:52     ` Maxime Ripard
2018-11-13 14:01     ` Hans Verkuil
2018-11-13 14:01       ` Hans Verkuil
2018-11-13 15:52       ` Maxime Ripard
2018-11-13 15:52         ` Maxime Ripard
2018-11-13 16:00         ` Hans Verkuil
2018-11-13 16:00           ` Hans Verkuil
2018-11-13 16:55           ` Thomas Petazzoni
2018-11-13 16:55             ` Thomas Petazzoni
2018-11-13 17:15             ` Hans Verkuil
2018-11-13 17:15               ` Hans Verkuil
2018-11-14  3:24 ` Chen-Yu Tsai
2018-11-14  3:24   ` Chen-Yu Tsai
2018-11-15 19:10   ` Maxime Ripard
2018-11-15 19:10     ` Maxime Ripard

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