Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1609333 > unrolled thread

[PATCH 1/5] Input: ambakmi - Convert to use devm_*()

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH 1/5] Input: ambakmi - Convert to use devm_*() Leo Yan <leo.yan@linaro.org> - 2017-03-26 16:50 +0200
    Re: [PATCH 1/5] Input: ambakmi - Convert to use devm_*() Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-26 17:00 +0200
      Re: [PATCH 1/5] Input: ambakmi - Convert to use devm_*() Leo Yan <leo.yan@linaro.org> - 2017-03-26 17:40 +0200

#1609333 — [PATCH 1/5] Input: ambakmi - Convert to use devm_*()

Convert driver to use devm_*() APIs so rely on driver model core layer
to manage resources. This eliminates error path boilerplate and makes
code neat.

This patch also fixes the memory leakage for 'kmi->io' when remove
module.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 drivers/input/serio/ambakmi.c | 44 ++++++++++---------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/drivers/input/serio/ambakmi.c b/drivers/input/serio/ambakmi.c
index c6606ca..d4814be 100644
--- a/drivers/input/serio/ambakmi.c
+++ b/drivers/input/serio/ambakmi.c
@@ -112,19 +112,11 @@ static int amba_kmi_probe(struct amba_device *dev,
 {
 	struct amba_kmi_port *kmi;
 	struct serio *io;
-	int ret;
-
-	ret = amba_request_regions(dev, NULL);
-	if (ret)
-		return ret;
-
-	kmi = kzalloc(sizeof(struct amba_kmi_port), GFP_KERNEL);
-	io = kzalloc(sizeof(struct serio), GFP_KERNEL);
-	if (!kmi || !io) {
-		ret = -ENOMEM;
-		goto out;
-	}
 
+	kmi = devm_kzalloc(&dev->dev, sizeof(*kmi), GFP_KERNEL);
+	io  = devm_kzalloc(&dev->dev, sizeof(*io), GFP_KERNEL);
+	if (!kmi || !io)
+		return -ENOMEM;
 
 	io->id.type	= SERIO_8042;
 	io->write	= amba_kmi_write;
@@ -136,31 +128,19 @@ static int amba_kmi_probe(struct amba_device *dev,
 	io->dev.parent	= &dev->dev;
 
 	kmi->io		= io;
-	kmi->base	= ioremap(dev->res.start, resource_size(&dev->res));
-	if (!kmi->base) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	kmi->base	= devm_ioremap_resource(&dev->dev, &dev->res);
+	if (IS_ERR(kmi->base))
+		return PTR_ERR(kmi->base);
 
-	kmi->clk = clk_get(&dev->dev, "KMIREFCLK");
-	if (IS_ERR(kmi->clk)) {
-		ret = PTR_ERR(kmi->clk);
-		goto unmap;
-	}
+	kmi->clk = devm_clk_get(&dev->dev, "KMIREFCLK");
+	if (IS_ERR(kmi->clk))
+		return PTR_ERR(kmi->clk);
 
 	kmi->irq = dev->irq[0];
 	amba_set_drvdata(dev, kmi);
 
 	serio_register_port(kmi->io);
 	return 0;
-
- unmap:
-	iounmap(kmi->base);
- out:
-	kfree(kmi);
-	kfree(io);
-	amba_release_regions(dev);
-	return ret;
 }
 
 static int amba_kmi_remove(struct amba_device *dev)
@@ -168,10 +148,6 @@ static int amba_kmi_remove(struct amba_device *dev)
 	struct amba_kmi_port *kmi = amba_get_drvdata(dev);
 
 	serio_unregister_port(kmi->io);
-	clk_put(kmi->clk);
-	iounmap(kmi->base);
-	kfree(kmi);
-	amba_release_regions(dev);
 	return 0;
 }
 
-- 
2.7.4

[toc] | [next] | [standalone]

#1609338

On Sun, Mar 26, 2017 at 10:41:50PM +0800, Leo Yan wrote:
> Convert driver to use devm_*() APIs so rely on driver model core layer
> to manage resources. This eliminates error path boilerplate and makes
> code neat.
> 
> This patch also fixes the memory leakage for 'kmi->io' when remove
> module.

No, it is not leaked, in fact, your patch introduces a use-after-free
bug.

kmi->io is of type "struct serio", and this structure has an embedded
"struct device".  The lifetime of any structure containing a "struct
device" is controlled by the lifetime of the struct device.

Once serio_register_port() has been called on it, it is up to the
serio layer to free this structure.

Therefore, your patch creates a bug, and so it gets a NAK.  There is no
resource leakage here.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

[toc] | [prev] | [next] | [standalone]

#1609344

On Sun, Mar 26, 2017 at 03:50:24PM +0100, Russell King - ARM Linux wrote:
> On Sun, Mar 26, 2017 at 10:41:50PM +0800, Leo Yan wrote:
> > Convert driver to use devm_*() APIs so rely on driver model core layer
> > to manage resources. This eliminates error path boilerplate and makes
> > code neat.
> > 
> > This patch also fixes the memory leakage for 'kmi->io' when remove
> > module.
> 
> No, it is not leaked, in fact, your patch introduces a use-after-free
> bug.
> 
> kmi->io is of type "struct serio", and this structure has an embedded
> "struct device".  The lifetime of any structure containing a "struct
> device" is controlled by the lifetime of the struct device.
> 
> Once serio_register_port() has been called on it, it is up to the
> serio layer to free this structure.
> 
> Therefore, your patch creates a bug, and so it gets a NAK.  There is no
> resource leakage here.

Thanks for reviewing. Now I understood and please ignore this patch
and patch 0005.

Thanks,
Leo Yan

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web