[PATCH] video: fbdev: skeletonfb.c: Adding code to managing allocation error

[PATCH] video: fbdev: skeletonfb.c: Adding code to managing allocation error

[Rickard Strandqvist]

Adding missing code for managing a memory allocation error that may occur.

This was partly found using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
---
 drivers/video/fbdev/skeletonfb.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/skeletonfb.c b/drivers/video/fbdev/skeletonfb.c
index fefde7c..ee6dc7e 100644
--- a/drivers/video/fbdev/skeletonfb.c
+++ b/drivers/video/fbdev/skeletonfb.c
@@ -692,6 +692,7 @@ static int xxxfb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
 
     if (!info) {
 	    /* goto error path */
+	    return -ENOMEM;
     }
 
     par = info->par;
@@ -746,6 +747,7 @@ static int xxxfb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
     info->pixmap.addr = kmalloc(PIXMAP_SIZE, GFP_KERNEL);
     if (!info->pixmap.addr) {
 	    /* goto error */
+	    return -ENOMEM;
     }
 
     info->pixmap.size = PIXMAP_SIZE;
-- 
1.7.10.4

Re: [PATCH] video: fbdev: skeletonfb.c: Adding code to managing allocation error

[Joe Perches]

(Adding Geert, who probably wrote most of this
 and likely might have forgotten all of it)

On Sat, 2014-06-21 at 15:17 +0200, Rickard Strandqvist wrote:
> Adding missing code for managing a memory allocation error that may occur.
> 
> This was partly found using a static code analysis program called cppcheck.

skeletonfb.c is not meant to be compiled.
It's a sample driver template.

Those /* goto error path */ lines are for
driver writers that use this to figure out
what to do.

The second return is not correct as it would
not free the first alloc'd block.

> diff --git a/drivers/video/fbdev/skeletonfb.c b/drivers/video/fbdev/skeletonfb.c
[]
> @@ -692,6 +692,7 @@ static int xxxfb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
>  
>      if (!info) {
>  	    /* goto error path */
> +	    return -ENOMEM;
>      }
>  
>      par = info->par;
> @@ -746,6 +747,7 @@ static int xxxfb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
>      info->pixmap.addr = kmalloc(PIXMAP_SIZE, GFP_KERNEL);
>      if (!info->pixmap.addr) {
>  	    /* goto error */
> +	    return -ENOMEM;
>      }
>  
>      info->pixmap.size = PIXMAP_SIZE;
> 

Re: [PATCH] video: fbdev: skeletonfb.c: Adding code to managing allocation error

[Geert Uytterhoeven]

On Sat, Jun 21, 2014 at 3:58 PM, Joe Perches <joe@perches.com> wrote:
> (Adding Geert, who probably wrote most of this
>  and likely might have forgotten all of it)
>
> On Sat, 2014-06-21 at 15:17 +0200, Rickard Strandqvist wrote:
>> Adding missing code for managing a memory allocation error that may occur.
>>
>> This was partly found using a static code analysis program called cppcheck.
>
> skeletonfb.c is not meant to be compiled.
> It's a sample driver template.

Yep.

> Those /* goto error path */ lines are for
> driver writers that use this to figure out
> what to do.

Still, it's nice if a sample driver has correct error handling.
Just comments are not good enough as guidance for some people ;-)

> The second return is not correct as it would
> not free the first alloc'd block.

Indeed. Better do it right.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] video: fbdev: skeletonfb.c: Adding code to managing allocation error

[Rickard Strandqvist]

Hi

Sounds like a good idea to have better error handling although it is
an example, even more important there.

At the first return nothing has been allocated, so it's ok I guess.
At the second I reflect about adding some deallocation, there are
comments on some form of goto error part which would appropriately
handle a deallocation. But all the other places in the code is just do
a return, that was why I chose to do it at the second return to.


Kind regards
Rickard Strandqvist


2014-06-21 22:48 GMT+02:00 Geert Uytterhoeven <geert@linux-m68k.org>:
> On Sat, Jun 21, 2014 at 3:58 PM, Joe Perches <joe@perches.com> wrote:
>> (Adding Geert, who probably wrote most of this
>>  and likely might have forgotten all of it)
>>
>> On Sat, 2014-06-21 at 15:17 +0200, Rickard Strandqvist wrote:
>>> Adding missing code for managing a memory allocation error that may occur.
>>>
>>> This was partly found using a static code analysis program called cppcheck.
>>
>> skeletonfb.c is not meant to be compiled.
>> It's a sample driver template.
>
> Yep.
>
>> Those /* goto error path */ lines are for
>> driver writers that use this to figure out
>> what to do.
>
> Still, it's nice if a sample driver has correct error handling.
> Just comments are not good enough as guidance for some people ;-)
>
>> The second return is not correct as it would
>> not free the first alloc'd block.
>
> Indeed. Better do it right.
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds