linux-kernel - Re: [PATCH kernel v10 05/34] powerpc/iommu: Always release iommu_table in iommu_free

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Date:	Wed, 13 May 2015 15:33:37 +1000
From:	Gavin Shan <gwshan@...ux.vnet.ibm.com>
To:	Alexey Kardashevskiy <aik@...abs.ru>
Cc:	linuxppc-dev@...ts.ozlabs.org,
	David Gibson <david@...son.dropbear.id.au>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	Gavin Shan <gwshan@...ux.vnet.ibm.com>,
	Wei Yang <weiyang@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH kernel v10 05/34] powerpc/iommu: Always release
 iommu_table in iommu_free_table()

On Tue, May 12, 2015 at 01:38:54AM +1000, Alexey Kardashevskiy wrote:
>At the moment iommu_free_table() only releases memory if
>the table was initialized for the platform code use, i.e. it had
>it_map initialized (which purpose is to track DMA memory space use).
>
>With dynamic DMA windows, we will need to be able to release
>iommu_table even if it was used for VFIO in which case it_map is NULL
>so does the patch.
>
>Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>

Reviewed-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>

>---
> arch/powerpc/kernel/iommu.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
>diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
>index 3d47eb3..2c02d4c 100644
>--- a/arch/powerpc/kernel/iommu.c
>+++ b/arch/powerpc/kernel/iommu.c
>@@ -714,8 +714,7 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
> 	unsigned int order;
>
> 	if (!tbl || !tbl->it_map) {
>-		printk(KERN_ERR "%s: expected TCE map for %s\n", __func__,
>-				node_name);
>+		kfree(tbl);

I'm not sure if the "tbl" needs to be checked against NULL as kfree() already
has the check. But it looks a bit strange to free NULL "tbl" from the code
itself.

Thanks,
Gavin

> 		return;
> 	}
>
>-- 
>2.4.0.rc3.8.gfb3e7d5
>

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