[PATCH] sbus: Introduce the use of the managed version of kzalloc

[PATCH] sbus: Introduce the use of the managed version of kzalloc

[Himangi Saraogi]

This patch moves data allocated using kzalloc to managed data allocated
using devm_kzalloc and cleans now unnecessary kfrees in probe and remove
functions. The header file is added to make the devm function explicitly
available. Also, unnecessary assignment statements and labels are
removed.

The following Coccinelle semantic patch was used for making a part of
the change:

@platform@
identifier p, probefn, removefn;
@@
struct platform_driver p = {
  .probe = probefn,
  .remove = removefn,
};

@prb@
identifier platform.probefn, pdev;
expression e, e1, e2;
@@
probefn(struct platform_device *pdev, ...) {
  <+...
- e = kzalloc(e1, e2)
+ e = devm_kzalloc(&pdev->dev, e1, e2)
  ...
?-kfree(e);
  ...+>
}

@rem depends on prb@
identifier platform.removefn;
expression e;
@@
removefn(...) {
  <...
- kfree(e);
  ...>
}

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
---
Not compile tested due to incompatible architecture.

To send to: "David S. Miller" <davem@davemloft.net>,sparclinux@vger.kernel.org,linux-kernel@vger.kernel.org

 drivers/sbus/char/display7seg.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/sbus/char/display7seg.c b/drivers/sbus/char/display7seg.c
index 7c71e7b..367b64d 100644
--- a/drivers/sbus/char/display7seg.c
+++ b/drivers/sbus/char/display7seg.c
@@ -20,6 +20,7 @@
 #include <asm/io.h>
 
 #include <asm/display7seg.h>
+#include <linux/device.h>
 
 #define D7S_MINOR	193
 #define DRIVER_NAME	"d7s"
@@ -173,22 +174,21 @@ static struct miscdevice d7s_miscdev = {
 static int d7s_probe(struct platform_device *op)
 {
 	struct device_node *opts;
-	int err = -EINVAL;
+	int err;
 	struct d7s *p;
 	u8 regs;
 
 	if (d7s_device)
-		goto out;
+		return -EINVAL;
 
-	p = kzalloc(sizeof(*p), GFP_KERNEL);
-	err = -ENOMEM;
+	p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
 	if (!p)
-		goto out;
+		return -ENOMEM;
 
 	p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
 	if (!p->regs) {
 		printk(KERN_ERR PFX "Cannot map chip registers\n");
-		goto out_free;
+		return -ENOMEM;
 	}
 
 	err = misc_register(&d7s_miscdev);
@@ -222,17 +222,11 @@ static int d7s_probe(struct platform_device *op)
 
 	dev_set_drvdata(&op->dev, p);
 	d7s_device = p;
-	err = 0;
-
-out:
-	return err;
+	return 0;
 
 out_iounmap:
 	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
-
-out_free:
-	kfree(p);
-	goto out;
+	return err;
 }
 
 static int d7s_remove(struct platform_device *op)
@@ -251,7 +245,6 @@ static int d7s_remove(struct platform_device *op)
 
 	misc_deregister(&d7s_miscdev);
 	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
-	kfree(p);
 
 	return 0;
 }
-- 
1.9.1

Re: [PATCH] sbus: Introduce the use of the managed version of kzalloc

[Sam Ravnborg]

Hi Himangi.

On Fri, May 23, 2014 at 02:05:36AM +0530, Himangi Saraogi wrote:
> This patch moves data allocated using kzalloc to managed data allocated
> using devm_kzalloc and cleans now unnecessary kfrees in probe and remove
> functions. The header file is added to make the devm function explicitly
> available. Also, unnecessary assignment statements and labels are
> removed.
> 
> ---
> Not compile tested due to incompatible architecture.
I can confirm that i builds.


> 
> To send to: "David S. Miller" <davem@davemloft.net>,sparclinux@vger.kernel.org,linux-kernel@vger.kernel.org
> 
>  drivers/sbus/char/display7seg.c | 23 ++++++++---------------
>  1 file changed, 8 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/sbus/char/display7seg.c b/drivers/sbus/char/display7seg.c
> index 7c71e7b..367b64d 100644
> --- a/drivers/sbus/char/display7seg.c
> +++ b/drivers/sbus/char/display7seg.c
> @@ -20,6 +20,7 @@
>  #include <asm/io.h>
>  
>  #include <asm/display7seg.h>
> +#include <linux/device.h>
>  
>  #define D7S_MINOR	193
>  #define DRIVER_NAME	"d7s"
> @@ -173,22 +174,21 @@ static struct miscdevice d7s_miscdev = {
>  static int d7s_probe(struct platform_device *op)
>  {
>  	struct device_node *opts;
> -	int err = -EINVAL;
> +	int err;
>  	struct d7s *p;
>  	u8 regs;
>  
>  	if (d7s_device)
> -		goto out;
> +		return -EINVAL;
>  
> -	p = kzalloc(sizeof(*p), GFP_KERNEL);
> -	err = -ENOMEM;
> +	p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
>  	if (!p)
> -		goto out;
> +		return -ENOMEM;
>  
>  	p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
>  	if (!p->regs) {
>  		printk(KERN_ERR PFX "Cannot map chip registers\n");
> -		goto out_free;
> +		return -ENOMEM;

Can you please explain how it can be correct to return "-ENOMEM",
when we fail to map the chip registers.
Before your patch this resulted in "-EINVAL" - so this is a change in behaviour.


>  	}
>  
>  	err = misc_register(&d7s_miscdev);
> @@ -222,17 +222,11 @@ static int d7s_probe(struct platform_device *op)
>  
>  	dev_set_drvdata(&op->dev, p);
>  	d7s_device = p;
> -	err = 0;
> -
> -out:
> -	return err;
> +	return 0;
>  
>  out_iounmap:
>  	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
> -
> -out_free:
> -	kfree(p);
> -	goto out;
> +	return err;
>  }
It is not am improvement IMO that you replace the nice goto
based error handling with random return points in the code.

	Sam

Re: [PATCH] sbus: Introduce the use of the managed version of kzalloc

[Sam Ravnborg]

On Fri, May 23, 2014 at 10:17:03PM +0200, Sam Ravnborg wrote:
> Hi Himangi.
> 
> On Fri, May 23, 2014 at 02:05:36AM +0530, Himangi Saraogi wrote:
> > This patch moves data allocated using kzalloc to managed data allocated
> > using devm_kzalloc and cleans now unnecessary kfrees in probe and remove
> > functions. The header file is added to make the devm function explicitly
> > available. Also, unnecessary assignment statements and labels are
> > removed.

Another note.
This patch touches only the display7seg dirver, so please prefix
your patch with "display7seg: bla bla"

	Sam

Re: [PATCH] sbus: Introduce the use of the managed version of kzalloc

[Julia Lawall]

On Fri, 23 May 2014, Sam Ravnborg wrote:

> Hi Himangi.
> 
> On Fri, May 23, 2014 at 02:05:36AM +0530, Himangi Saraogi wrote:
> > This patch moves data allocated using kzalloc to managed data allocated
> > using devm_kzalloc and cleans now unnecessary kfrees in probe and remove
> > functions. The header file is added to make the devm function explicitly
> > available. Also, unnecessary assignment statements and labels are
> > removed.
> > 
> > ---
> > Not compile tested due to incompatible architecture.
> I can confirm that i builds.
> 
> 
> > 
> > To send to: "David S. Miller" <davem@davemloft.net>,sparclinux@vger.kernel.org,linux-kernel@vger.kernel.org
> > 
> >  drivers/sbus/char/display7seg.c | 23 ++++++++---------------
> >  1 file changed, 8 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/sbus/char/display7seg.c b/drivers/sbus/char/display7seg.c
> > index 7c71e7b..367b64d 100644
> > --- a/drivers/sbus/char/display7seg.c
> > +++ b/drivers/sbus/char/display7seg.c
> > @@ -20,6 +20,7 @@
> >  #include <asm/io.h>
> >  
> >  #include <asm/display7seg.h>
> > +#include <linux/device.h>
> >  
> >  #define D7S_MINOR	193
> >  #define DRIVER_NAME	"d7s"
> > @@ -173,22 +174,21 @@ static struct miscdevice d7s_miscdev = {
> >  static int d7s_probe(struct platform_device *op)
> >  {
> >  	struct device_node *opts;
> > -	int err = -EINVAL;
> > +	int err;
> >  	struct d7s *p;
> >  	u8 regs;
> >  
> >  	if (d7s_device)
> > -		goto out;
> > +		return -EINVAL;
> >  
> > -	p = kzalloc(sizeof(*p), GFP_KERNEL);
> > -	err = -ENOMEM;
> > +	p = devm_kzalloc(&op->dev, sizeof(*p), GFP_KERNEL);
> >  	if (!p)
> > -		goto out;
> > +		return -ENOMEM;
> >  
> >  	p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
> >  	if (!p->regs) {
> >  		printk(KERN_ERR PFX "Cannot map chip registers\n");
> > -		goto out_free;
> > +		return -ENOMEM;
> 
> Can you please explain how it can be correct to return "-ENOMEM",
> when we fail to map the chip registers.
> Before your patch this resulted in "-EINVAL" - so this is a change in behaviour.

I don't see it.  It looks to me that it returned ENOMEM, due to the 
assignment after the kzalloc.

julia

> >  	}
> >  
> >  	err = misc_register(&d7s_miscdev);
> > @@ -222,17 +222,11 @@ static int d7s_probe(struct platform_device *op)
> >  
> >  	dev_set_drvdata(&op->dev, p);
> >  	d7s_device = p;
> > -	err = 0;
> > -
> > -out:
> > -	return err;
> > +	return 0;
> >  
> >  out_iounmap:
> >  	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
> > -
> > -out_free:
> > -	kfree(p);
> > -	goto out;
> > +	return err;
> >  }
> It is not am improvement IMO that you replace the nice goto
> based error handling with random return points in the code.
> 
> 	Sam
>