Subject: Re: [PATCH 2/3] iommu/fsl: Fix the device domain attach condition.

From: Joerg Roedel <[email-masked]>
Date: Fri, 4 Jul 2014 12:54:31 +0200

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 ...

> @@ -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?

>  	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;
 	spin_unlock_irqrestore(&device_domain_lock, flags);
 
 }