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SubjectRE: [PATCH 2/3] iommu/fsl: Fix the device domain attach condition.
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> -----Original Message-----
> From: Joerg Roedel [mailto:joro@8bytes.org]
> Sent: Friday, July 04, 2014 4:25 PM
> To: Sethi Varun-B16395
> Cc: iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org;
> linuxppc-dev@lists.ozlabs.org; alex.williamson@redhat.com
> Subject: Re: [PATCH 2/3] iommu/fsl: Fix the device domain attach
> condition.
>
> Hmm,
>
> On Tue, Jun 24, 2014 at 07:27:16PM +0530, Varun Sethi wrote:
> > - old_domain_info = find_domain(dev);
> > + old_domain_info = dev->archdata.iommu_domain;
> > if (old_domain_info && old_domain_info->domain != dma_domain) {
> > spin_unlock_irqrestore(&device_domain_lock, flags);
> > detach_device(dev, old_domain_info->domain);
>
> Wouldn't this set dev->archdata.iommu_domain to NULL anyway, so that ...
>
Not for the case where device has multiple LIODNs.

> > @@ -399,7 +394,7 @@ static void attach_device(struct fsl_dma_domain
> *dma_domain, int liodn, struct d
> > * the info for the first LIODN as all
> > * LIODNs share the same domain
> > */
> > - if (!old_domain_info)
> > + if (!dev->archdata.iommu_domain)
> > dev->archdata.iommu_domain = info;
>
> We already know that it _must_ be NULL here?
>

That won't be true for devices having multiple LIODNs

> > spin_unlock_irqrestore(&device_domain_lock, flags);
>
> This would shrink down the patch to:
>
> diff --git a/drivers/iommu/fsl_pamu_domain.c
> b/drivers/iommu/fsl_pamu_domain.c index 93072ba..d21b554 100644
> --- a/drivers/iommu/fsl_pamu_domain.c
> +++ b/drivers/iommu/fsl_pamu_domain.c
> @@ -399,8 +399,7 @@ static void attach_device(struct fsl_dma_domain
> *dma_domain, int liodn, struct d
> * the info for the first LIODN as all
> * LIODNs share the same domain
> */
> - if (!old_domain_info)
> - dev->archdata.iommu_domain = info;
> + dev->archdata.iommu_domain = info;

For devices having multiple LIODNs, we don't want to overwrite the info.

-Varun



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