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

Commit Message

Leo Yan March 26, 2017, 2:41 p.m. UTC

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 <[e-mail]>
---
 drivers/input/serio/ambakmi.c | 44 ++++++++++---------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

Comments

Leo Yan March 26, 2017, 3:23 p.m. UTC | #1

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

Patch

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;
 }