linux-kernel - [PATCH v8 01/29] iommufd: Report unmapped bytes in the error path of iopt_unmap_iova

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Message-ID: <7da10d5887b88ef9d1231dba152bbd83f5403aac.1751677708.git.nicolinc@nvidia.com>
Date: Fri, 4 Jul 2025 18:13:17 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: <jgg@...dia.com>, <kevin.tian@...el.com>, <corbet@....net>,
	<will@...nel.org>
CC: <bagasdotme@...il.com>, <robin.murphy@....com>, <joro@...tes.org>,
	<thierry.reding@...il.com>, <vdumpa@...dia.com>, <jonathanh@...dia.com>,
	<shuah@...nel.org>, <jsnitsel@...hat.com>, <nathan@...nel.org>,
	<peterz@...radead.org>, <yi.l.liu@...el.com>, <mshavit@...gle.com>,
	<praan@...gle.com>, <zhangzekun11@...wei.com>, <iommu@...ts.linux.dev>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-tegra@...r.kernel.org>,
	<linux-kselftest@...r.kernel.org>, <patches@...ts.linux.dev>,
	<mochs@...dia.com>, <alok.a.tiwari@...cle.com>, <vasant.hegde@....com>,
	<dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>
Subject: [PATCH v8 01/29] iommufd: Report unmapped bytes in the error path of iopt_unmap_iova_range

There are callers that read the unmapped bytes even when rc != 0. Thus, do
not forget to report it in the error path too.

Fixes: 8d40205f6093 ("iommufd: Add kAPI toward external drivers for kernel access")
Cc: stable@...r.kernel.org
Reviewed-by: Kevin Tian <kevin.tian@...el.com>
Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
 drivers/iommu/iommufd/io_pagetable.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index 13d010f19ed1..22fc3a12109f 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -743,8 +743,10 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start,
 			iommufd_access_notify_unmap(iopt, area_first, length);
 			/* Something is not responding to unmap requests. */
 			tries++;
-			if (WARN_ON(tries > 100))
-				return -EDEADLOCK;
+			if (WARN_ON(tries > 100)) {
+				rc = -EDEADLOCK;
+				goto out_unmapped;
+			}
 			goto again;
 		}
 
@@ -766,6 +768,7 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start,
 out_unlock_iova:
 	up_write(&iopt->iova_rwsem);
 	up_read(&iopt->domains_rwsem);
+out_unmapped:
 	if (unmapped)
 		*unmapped = unmapped_bytes;
 	return rc;
-- 
2.43.0