Re: [PATCH] iommu: Improve exception handling in iommu_group_alloc()

Re: [PATCH] iommu: Improve exception handling in iommu_group_alloc()

[Markus Elfring]

> Optimize the error handling to free the resources correctly when
> failed to allocate an iommu group.

* I would not categorise the desired completion of exception handling
  as a software optimisation.

* Would you like to add the tag “Fixes” to the commit message?

* I suggest to avoid the specification of duplicate function calls.
  Will it be helpful to add a few jump targets?
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162#n455

Regards,
Markus

Re: [PATCH] iommu: Improve exception handling in iommu_group_alloc()

[Baolin Wang]

On Mon, Jun 01, 2020 at 02:38:05PM +0200, Markus Elfring wrote:
> > Optimize the error handling to free the resources correctly when
> > failed to allocate an iommu group.
> 
> * I would not categorise the desired completion of exception handling
>   as a software optimisation.
> 
> * Would you like to add the tag “Fixes” to the commit message?

Sure.

> 
> * I suggest to avoid the specification of duplicate function calls.
>   Will it be helpful to add a few jump targets?
>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162#n455

I don't think it is helpful or readable to add some jump targets here, since the exception handling is very simple here.

Re: iommu: Improve exception handling in iommu_group_alloc()

[Markus Elfring]

>> * I suggest to avoid the specification of duplicate function calls.
>>   Will it be helpful to add a few jump targets?
>>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162#n455
>
> I don't think it is helpful or readable to add some jump targets here,
> since the exception handling is very simple here.

Do you disagree to the application of the Linux coding style then
for the recommended exception handling?

Regards,
Markus

Re: iommu: Improve exception handling in iommu_group_alloc()

[Baolin Wang]

On Tue, Jun 02, 2020 at 07:01:02AM +0200, Markus Elfring wrote:
> >> * I suggest to avoid the specification of duplicate function calls.
> >>   Will it be helpful to add a few jump targets?
> >>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162#n455
> >
> > I don't think it is helpful or readable to add some jump targets here,
> > since the exception handling is very simple here.
> 
> Do you disagree to the application of the Linux coding style then
> for the recommended exception handling?

No, that's not what I mean. My point is the exception handling in this
patch is simple and no need to add 'goto' statement which does not help
to improve readability. And I agree it is helpful for the cases where a
function exits from multiple locations and more same cleanup work need
to do.

Re: iommu: Improve exception handling in iommu_group_alloc()

[Markus Elfring]

>> Do you disagree to the application of the Linux coding style then
>> for the recommended exception handling?
>
> No, that's not what I mean. My point is the exception handling in this
> patch is simple and no need to add 'goto' statement which does not help
> to improve readability.

Do we come along different programming imaginations?


> And I agree it is helpful for the cases where a function exits from multiple locations
> and more same cleanup work need to do.

Can this view fit also to calls of the function “kobject_put”?
https://lore.kernel.org/patchwork/patch/1251326/
https://lore.kernel.org/linux-iommu/8bfd018ef4add083a35a6a94a8da045cf3af51b6.1591063271.git.baolin.wang@linux.alibaba.com/
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/iommu/iommu.c?id=7cc31613734c4870ae32f5265d576ef296621343#n478
https://elixir.bootlin.com/linux/v5.7/source/drivers/iommu/iommu.c#L478

Regards,
Markus