linux-kernel - Re: [PATCH v7 10/10] iommu/arm-smmu: call iommu_free_reserved_iova

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Message-ID: <5717BDF1.7030400@arm.com>
Date:	Wed, 20 Apr 2016 18:35:45 +0100
From:	Robin Murphy <robin.murphy@....com>
To:	Eric Auger <eric.auger@...aro.org>, eric.auger@...com,
	alex.williamson@...hat.com, will.deacon@....com, joro@...tes.org,
	tglx@...utronix.de, jason@...edaemon.net, marc.zyngier@....com,
	christoffer.dall@...aro.org, linux-arm-kernel@...ts.infradead.org
Cc:	patches@...aro.org, linux-kernel@...r.kernel.org,
	Bharat.Bhushan@...escale.com, pranav.sawargaonkar@...il.com,
	p.fedin@...sung.com, iommu@...ts.linux-foundation.org,
	Jean-Philippe.Brucker@....com, julien.grall@....com
Subject: Re: [PATCH v7 10/10] iommu/arm-smmu: call
 iommu_free_reserved_iova_domain on domain destruction

On 19/04/16 17:56, Eric Auger wrote:
> When the domain gets destroyed, let's make sure all reserved iova
> resources get released.
>
> Choice is made to put that call in arm-smmu(-v3).c to do something similar
> to what was done for iommu_put_dma_cookie.
>
> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>
> ---
>
> v7: new
> ---
>   drivers/iommu/arm-smmu-v3.c | 2 ++
>   drivers/iommu/arm-smmu.c    | 2 ++
>   2 files changed, 4 insertions(+)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index a077a35..afd0dac 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -22,6 +22,7 @@
>
>   #include <linux/delay.h>
>   #include <linux/dma-iommu.h>
> +#include <linux/dma-reserved-iommu.h>
>   #include <linux/err.h>
>   #include <linux/interrupt.h>
>   #include <linux/iommu.h>
> @@ -1444,6 +1445,7 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
>   	struct arm_smmu_device *smmu = smmu_domain->smmu;
>
>   	iommu_put_dma_cookie(domain);
> +	iommu_free_reserved_iova_domain(domain);

Yikes! No, drivers shouldn't be randomly freeing things they didn't 
allocate - the owner of the domain, who presumably allocated the thing, 
can call that right _before_ they call iommu_domain_free().

>   	free_io_pgtable_ops(smmu_domain->pgtbl_ops);
>
>   	/* Free the CD and ASID, if we allocated them */
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 8cd7b8a..492339f 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -30,6 +30,7 @@
>
>   #include <linux/delay.h>
>   #include <linux/dma-iommu.h>
> +#include <linux/dma-reserved-iommu.h>
>   #include <linux/dma-mapping.h>
>   #include <linux/err.h>
>   #include <linux/interrupt.h>
> @@ -1009,6 +1010,7 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
>   	 * already been detached.
>   	 */
>   	iommu_put_dma_cookie(domain);
> +	iommu_free_reserved_iova_domain(domain);

...which has the added bonus of preventing needless duplication everywhere.

Robin.

>   	arm_smmu_destroy_domain_context(domain);
>   	kfree(smmu_domain);
>   }
>