linux-kernel - [PATCH v2 2/4] iommu: Resolve ops in iommu_init

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Message-Id: <fa4b6cfc67a352488b7f4e0b736008307ce9ac2e.1740753261.git.robin.murphy@arm.com>
Date: Fri, 28 Feb 2025 15:46:31 +0000
From: Robin Murphy <robin.murphy@....com>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Hanjun Guo <guohanjun@...wei.com>,
	Sudeep Holla <sudeep.holla@....com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Russell King <linux@...linux.org.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Stuart Yoder <stuyoder@...il.com>,
	Laurentiu Tudor <laurentiu.tudor@....com>,
	Nipun Gupta <nipun.gupta@....com>,
	Nikhil Agarwal <nikhil.agarwal@....com>,
	Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Cc: linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	iommu@...ts.linux.dev,
	devicetree@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Charan Teja Kalla <quic_charante@...cinc.com>
Subject: [PATCH v2 2/4] iommu: Resolve ops in iommu_init_device()

Since iommu_init_device() was factored out, it is in fact the only
consumer of the ops which __iommu_probe_device() is resolving, so let it
do that itself rather than passing them in. This also puts the ops
lookup at a more logical point relative to the rest of the flow through
__iommu_probe_device().

Signed-off-by: Robin Murphy <robin.murphy@....com>
---

v2: New

 drivers/iommu/iommu.c | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 179617bb412d..37b7088e129a 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -404,14 +404,28 @@ EXPORT_SYMBOL_GPL(dev_iommu_priv_set);
  * Init the dev->iommu and dev->iommu_group in the struct device and get the
  * driver probed
  */
-static int iommu_init_device(struct device *dev, const struct iommu_ops *ops)
+static int iommu_init_device(struct device *dev)
 {
+	const struct iommu_ops *ops;
 	struct iommu_device *iommu_dev;
 	struct iommu_group *group;
 	int ret;
 
 	if (!dev_iommu_get(dev))
 		return -ENOMEM;
+	/*
+	 * For FDT-based systems and ACPI IORT/VIOT, drivers register IOMMU
+	 * instances with non-NULL fwnodes, and client devices should have been
+	 * identified with a fwspec by this point. Otherwise, we can currently
+	 * assume that only one of Intel, AMD, s390, PAMU or legacy SMMUv2 can
+	 * be present, and that any of their registered instances has suitable
+	 * ops for probing, and thus cheekily co-opt the same mechanism.
+	 */
+	ops = iommu_fwspec_ops(dev->iommu->fwspec);
+	if (!ops) {
+		ret = -ENODEV;
+		goto err_free;
+	}
 
 	if (!try_module_get(ops->owner)) {
 		ret = -EINVAL;
@@ -514,22 +528,10 @@ DEFINE_MUTEX(iommu_probe_device_lock);
 
 static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
 {
-	const struct iommu_ops *ops;
 	struct iommu_group *group;
 	struct group_device *gdev;
 	int ret;
 
-	/*
-	 * For FDT-based systems and ACPI IORT/VIOT, drivers register IOMMU
-	 * instances with non-NULL fwnodes, and client devices should have been
-	 * identified with a fwspec by this point. Otherwise, we can currently
-	 * assume that only one of Intel, AMD, s390, PAMU or legacy SMMUv2 can
-	 * be present, and that any of their registered instances has suitable
-	 * ops for probing, and thus cheekily co-opt the same mechanism.
-	 */
-	ops = iommu_fwspec_ops(dev_iommu_fwspec_get(dev));
-	if (!ops)
-		return -ENODEV;
 	/*
 	 * Serialise to avoid races between IOMMU drivers registering in
 	 * parallel and/or the "replay" calls from ACPI/OF code via client
@@ -543,7 +545,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
 	if (dev->iommu_group)
 		return 0;
 
-	ret = iommu_init_device(dev, ops);
+	ret = iommu_init_device(dev);
 	if (ret)
 		return ret;
 
-- 
2.39.2.101.g768bb238c484.dirty