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Re: [PATCH 2/2] vfio: powerpc/spapr: One function call less in tce_iommu_attach_group() after kzalloc() failure

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  Re: [PATCH 2/2] vfio: powerpc/spapr: One function call less in  tce_iommu_attach_group() after kzalloc() failure Alexey Kardashevskiy <aik@ozlabs.ru> - 2015-06-29 01:50 +0200
    Re: vfio: powerpc/spapr: One function call less in  tce_iommu_attach_group() after kzalloc() failure Alexey Kardashevskiy <aik@ozlabs.ru> - 2015-06-30 02:40 +0200
      Re: vfio: powerpc/spapr: One function call less in  tce_iommu_attach_group() after kzalloc() failure Alexey Kardashevskiy <aik@ozlabs.ru> - 2015-06-30 12:40 +0200

#1173583 — Re: [PATCH 2/2] vfio: powerpc/spapr: One function call less in tce_iommu_attach_group() after kzalloc() failure

On 06/29/2015 02:24 AM, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sun, 28 Jun 2015 17:58:42 +0200
>
> The kfree() function was called even if a previous memory allocation
> try failed.

tcegrp will be NULL and kfree() can handle this just fine (is not it the 
whole point of this patchset - remove the check and just call kfree() even 
if the pointer is NULL?). And if you wanted another label, than the 
existing one should have been renamed to "free_exit" or "free_unlock_exit" 
and new one would be "unlock_exit".



> This implementation detail could be improved by the introduction
> of another jump label.
>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>   drivers/vfio/vfio_iommu_spapr_tce.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 50ddfac..2523075 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -1200,7 +1200,7 @@ static int tce_iommu_attach_group(void *iommu_data,
>   	tcegrp = kzalloc(sizeof(*tcegrp), GFP_KERNEL);
>   	if (!tcegrp) {
>   		ret = -ENOMEM;
> -		goto unlock_exit;
> +		goto unlock_container;
>   	}
>
>   	if (!table_group->ops || !table_group->ops->take_ownership ||
> @@ -1217,7 +1217,7 @@ static int tce_iommu_attach_group(void *iommu_data,
>   unlock_exit:
>   	if (ret)
>   		kfree(tcegrp);
> -
> +unlock_container:
>   	mutex_unlock(&container->lock);
>
>   	return ret;
>


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#1174158 — Re: vfio: powerpc/spapr: One function call less in tce_iommu_attach_group() after kzalloc() failure

On 06/29/2015 04:02 PM, SF Markus Elfring wrote:
>> tcegrp will be NULL and kfree() can handle this just fine
>
> The affected function did not show this API knowledge, did it?


but you fixed this in 1/2 :)

>
>
>> (is not it the whole point of this patchset
>> - remove the check and just call kfree() even if the pointer is NULL?).
>
> Partly, yes.
>
>
>> And if you wanted another label,
>
> I suggest this to improve corresponding exception handling.
>
>
>> than the existing one should have been renamed to "free_exit" or "free_unlock_exit"
>> and new one would be "unlock_exit".
>
> I chose a smaller change at this place.


I'd just drop this patch.


> I am not familiar enough with other called functions there at the moment.
> Are the remaining goto statements also update candidates?




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#1174429 — Re: vfio: powerpc/spapr: One function call less in tce_iommu_attach_group() after kzalloc() failure

On 06/30/2015 04:08 PM, SF Markus Elfring wrote:
>>>> than the existing one should have been renamed to "free_exit" or "free_unlock_exit"
>>>> and new one would be "unlock_exit".
>>>
>>> I chose a smaller change at this place.
>>
>> I'd just drop this patch.
>
> How do you think about to improve the affected jump labels
> a bit more there?

This branch is very unlikely to work ever so I cannot think of any 
improvement here.



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