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From: Will Deacon <will@kernel.org>
To: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Cc: "Isaac J. Manjarres" <isaacm@codeaurora.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Saravana Kannan <saravanak@google.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Will Deacon <will@kernel.org>
Subject: [PATCH v2 5/9] iommu/of: Take a ref to the IOMMU driver during ->of_xlate()
Date: Fri,  8 Nov 2019 15:16:04 +0000
Message-ID: <20191108151608.20932-6-will@kernel.org> (raw)
In-Reply-To: <20191108151608.20932-1-will@kernel.org>

Ensure that we hold a reference to the IOMMU driver module while calling
the '->of_xlate()' callback during early device probing.

Signed-off-by: Will Deacon <will@kernel.org>
---
 drivers/iommu/of_iommu.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 78faa9f73a91..25491403a0bd 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -8,6 +8,7 @@
 #include <linux/export.h>
 #include <linux/iommu.h>
 #include <linux/limits.h>
+#include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_iommu.h>
 #include <linux/of_pci.h>
@@ -89,16 +90,16 @@ static int of_iommu_xlate(struct device *dev,
 {
 	const struct iommu_ops *ops;
 	struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
-	int err;
+	int ret;
 
 	ops = iommu_ops_from_fwnode(fwnode);
 	if ((ops && !ops->of_xlate) ||
 	    !of_device_is_available(iommu_spec->np))
 		return NO_IOMMU;
 
-	err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
-	if (err)
-		return err;
+	ret = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
+	if (ret)
+		return ret;
 	/*
 	 * The otherwise-empty fwspec handily serves to indicate the specific
 	 * IOMMU device we're waiting for, which will be useful if we ever get
@@ -107,7 +108,12 @@ static int of_iommu_xlate(struct device *dev,
 	if (!ops)
 		return driver_deferred_probe_check_state(dev);
 
-	return ops->of_xlate(dev, iommu_spec);
+	if (!try_module_get(ops->owner))
+		return -ENODEV;
+
+	ret = ops->of_xlate(dev, iommu_spec);
+	module_put(ops->owner);
+	return ret;
 }
 
 struct of_pci_iommu_alias_info {
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog

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  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-08 15:15 [PATCH v2 0/9] iommu: Permit modular builds of ARM SMMU[v3] drivers Will Deacon
2019-11-08 15:16 ` [PATCH v2 1/9] drivers/iommu: Export core IOMMU API symbols to permit modular drivers Will Deacon
2019-11-08 15:16 ` [PATCH v2 2/9] iommu/of: Request ACS from the PCI core when configuring IOMMU linkage Will Deacon
2019-11-08 15:16 ` [PATCH v2 3/9] PCI: Export pci_ats_disabled() as a GPL symbol to modules Will Deacon
2019-11-08 15:16 ` [PATCH v2 4/9] drivers/iommu: Take a ref to the IOMMU driver prior to ->add_device() Will Deacon
2019-11-08 15:16 ` Will Deacon [this message]
2019-11-08 15:16 ` [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular" Will Deacon
2019-11-08 16:17   ` John Garry
2019-11-08 16:44     ` John Garry
2019-11-08 16:47       ` Will Deacon
2019-11-08 17:25         ` John Garry
2019-11-08 17:32           ` Will Deacon
2019-11-08 17:48             ` Will Deacon
2019-11-08 18:00               ` John Garry
2019-11-08 17:49             ` John Garry
2019-11-08 15:16 ` [PATCH v2 7/9] iommu/arm-smmu-v3: Allow building as a module Will Deacon
2019-11-08 15:16 ` [PATCH v2 8/9] Revert "iommu/arm-smmu: Make arm-smmu explicitly non-modular" Will Deacon
2019-11-08 15:16 ` [PATCH v2 9/9] iommu/arm-smmu: Allow building as a module Will Deacon

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