linux-kernel - [PATCH 3/3] iommu/vt-d: Simplify domain_attach

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Message-ID: <20250423031020.2189546-4-baolu.lu@linux.intel.com>
Date: Wed, 23 Apr 2025 11:10:20 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Kevin Tian <kevin.tian@...el.com>
Cc: iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 3/3] iommu/vt-d: Simplify domain_attach_iommu()

Use the __free(kfree) attribute with kzalloc() to automatically handle
the freeing of the allocated struct iommu_domain_info on error or early
exit paths, eliminating the need for explicit kfree() calls in error
handling branches.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.c | 29 ++++++++---------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 3a9ea0ad2cd3..12382c85495f 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1337,13 +1337,14 @@ static bool first_level_by_default(struct intel_iommu *iommu)
 
 int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
 {
-	struct iommu_domain_info *info, *curr;
-	int num, ret = -ENOSPC;
+	struct iommu_domain_info *curr;
+	int num;
 
 	if (domain->domain.type == IOMMU_DOMAIN_SVA)
 		return 0;
 
-	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	struct iommu_domain_info *info __free(kfree) =
+		kzalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return -ENOMEM;
 
@@ -1351,34 +1352,20 @@ int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
 	curr = xa_load(&domain->iommu_array, iommu->seq_id);
 	if (curr) {
 		curr->refcnt++;
-		kfree(info);
 		return 0;
 	}
 
 	num = ida_alloc_range(&iommu->domain_ida, FLPT_DEFAULT_DID + 1,
 			      cap_ndoms(iommu->cap) - 1, GFP_KERNEL);
-	if (num < 0) {
-		pr_err("%s: No free domain ids\n", iommu->name);
-		goto err_unlock;
-	}
+	if (num < 0)
+		return num;
 
 	info->refcnt	= 1;
 	info->did	= num;
 	info->iommu	= iommu;
-	curr = xa_cmpxchg(&domain->iommu_array, iommu->seq_id,
-			  NULL, info, GFP_KERNEL);
-	if (curr) {
-		ret = xa_err(curr) ? : -EBUSY;
-		goto err_clear;
-	}
 
-	return 0;
-
-err_clear:
-	ida_free(&iommu->domain_ida, info->did);
-err_unlock:
-	kfree(info);
-	return ret;
+	return xa_err(xa_store(&domain->iommu_array, iommu->seq_id,
+			       no_free_ptr(info), GFP_KERNEL));
 }
 
 void domain_detach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
-- 
2.43.0