iommu/dma: Remove redundant locking

This reverts commit ac9a5d5.

iommu_dma_init_domain() is now only called under the group mutex, as it
should be given that that the default domain belongs to the group, so
the additional internal locking is no longer needed.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/a943d4c198e6a1fffe998337d577dc3aa7f660a9.1740585469.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/dma-iommu.c

@@ -87,7 +87,6 @@ struct iommu_dma_cookie {
 	struct iommu_domain		*fq_domain;
 	/* Options for dma-iommu use */
 	struct iommu_dma_options	options;
-	struct mutex			mutex;
 };
 
 static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);
@@ -401,7 +400,6 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
 	if (!domain->iova_cookie)
 		return -ENOMEM;
 
-	mutex_init(&domain->iova_cookie->mutex);
 	iommu_domain_set_sw_msi(domain, iommu_dma_sw_msi);
 	return 0;
 }
@@ -709,23 +707,20 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, struct device *dev
 			 domain->geometry.aperture_start >> order);
 
 	/* start_pfn is always nonzero for an already-initialised domain */
-	mutex_lock(&cookie->mutex);
 	if (iovad->start_pfn) {
 		if (1UL << order != iovad->granule ||
 		    base_pfn != iovad->start_pfn) {
 			pr_warn("Incompatible range for DMA domain\n");
-			ret = -EFAULT;
-			goto done_unlock;
+			return -EFAULT;
 		}
 
-		ret = 0;
-		goto done_unlock;
+		return 0;
 	}
 
 	init_iova_domain(iovad, 1UL << order, base_pfn);
 	ret = iova_domain_init_rcaches(iovad);
 	if (ret)
-		goto done_unlock;
+		return ret;
 
 	iommu_dma_init_options(&cookie->options, dev);
 
@@ -734,11 +729,7 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, struct device *dev
 	    (!device_iommu_capable(dev, IOMMU_CAP_DEFERRED_FLUSH) || iommu_dma_init_fq(domain)))
 		domain->type = IOMMU_DOMAIN_DMA;
 
-	ret = iova_reserve_iommu_regions(dev, domain);
-
-done_unlock:
-	mutex_unlock(&cookie->mutex);
-	return ret;
+	return iova_reserve_iommu_regions(dev, domain);
 }
 
 /**