linux-kernel - Re: [PATCH 2/2] vfio: powerpc/spapr: One function call less in tce_iommu_attach

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Message-ID: <5590862A.3010603@ozlabs.ru>
Date:	Mon, 29 Jun 2015 09:41:30 +1000
From:	Alexey Kardashevskiy <aik@...abs.ru>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>,
	Alex Williamson <alex.williamson@...hat.com>,
	kvm@...r.kernel.org
Cc:	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>,
	Michael Ellerman <mpe@...erman.id.au>
Subject: 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@...rs.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@...rs.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;
>


-- 
Alexey
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