Re: question regarding drivers/staging/iio/adc/ad7280a.c

Re: question regarding drivers/staging/iio/adc/ad7280a.c

[Jonathan Cameron]

On 14/07/14 21:31, Himangi Saraogi wrote:
> Hi,
>
> The code seems to have a memory leak. The function ad7280_attr_init
> calls kasprintf a number of times, which calls kmalloc (or more
> precisely kmalloc_track_caller), but this data does not ever seem to
> be freed. I propose to introduce a devm_  version of kasprintf, which
> will be useful for other files also. I am not very sure that will it
> be useful to introduce a bunch of kfrees, just to remove the memory
> leaks immediately, but I think it would be safer just to devm
> everything, so then one is sure that everything is freed as it should
> be, in the right order.
>
The question here is whether such a memory leak squashing would be
worth applying to stable.  Personally I'd go with no. In which case
feel free to fix it via the introduction of a devm version.


Jonathan
> Thanks
> Himangi

Re: question regarding drivers/staging/iio/adc/ad7280a.c

[Lars-Peter Clausen]

On 07/15/2014 07:31 PM, Jonathan Cameron wrote:
> On 14/07/14 21:31, Himangi Saraogi wrote:
>> Hi,
>>
>> The code seems to have a memory leak. The function ad7280_attr_init
>> calls kasprintf a number of times, which calls kmalloc (or more
>> precisely kmalloc_track_caller), but this data does not ever seem to
>> be freed. I propose to introduce a devm_  version of kasprintf, which
>> will be useful for other files also. I am not very sure that will it
>> be useful to introduce a bunch of kfrees, just to remove the memory
>> leaks immediately, but I think it would be safer just to devm
>> everything, so then one is sure that everything is freed as it should
>> be, in the right order.
>>
> The question here is whether such a memory leak squashing would be
> worth applying to stable.  Personally I'd go with no. In which case
> feel free to fix it via the introduction of a devm version.

devm is probably fine here.

The long term fix should be to switch the driver to use 
iio_chan_spec_ext_info infrastructure which will handle the allocation and 
freeing internally in the IIO framework.

- Lars

Re: question regarding drivers/staging/iio/adc/ad7280a.c

[Greg Kroah-Hartman]

On Thu, Jul 17, 2014 at 11:40:04PM +0530, Himangi Saraogi wrote:
> Hi,
> 
> I have sent in a patch for adding devm_kasprintf https://lkml.org/lkml/2014/7/
> 16/667.
> I will be updating this file and send in a patch once it is accepted. Was it
> the right thing
> to do to send the devm_kasprintf patch separately from the patch on the file to
> use it for,
> because the person applying the later may not see the dependency?

Well, you should have told me there was a dependancy :)

As I'll end up taking both of these patches in the end, I'll queue your
devm_kasprintf patch up in my staging-next tree so that it will work
properly with your patch.

thanks,

greg k-h

Re: question regarding drivers/staging/iio/adc/ad7280a.c

[Greg Kroah-Hartman]

On Thu, Jul 17, 2014 at 01:58:15PM -0700, Greg Kroah-Hartman wrote:
> On Thu, Jul 17, 2014 at 11:40:04PM +0530, Himangi Saraogi wrote:
> > Hi,
> > 
> > I have sent in a patch for adding devm_kasprintf https://lkml.org/lkml/2014/7/
> > 16/667.
> > I will be updating this file and send in a patch once it is accepted. Was it
> > the right thing
> > to do to send the devm_kasprintf patch separately from the patch on the file to
> > use it for,
> > because the person applying the later may not see the dependency?
> 
> Well, you should have told me there was a dependancy :)
> 
> As I'll end up taking both of these patches in the end, I'll queue your
> devm_kasprintf patch up in my staging-next tree so that it will work
> properly with your patch.

Now applied there, so all should be good, right?

thanks,

greg k-h