[PATCH v2 3/4] iommu: Keep dev->iommu state consistent
Robin Murphy
robin.murphy at arm.com
Fri Feb 28 07:46:32 PST 2025
At the moment, if of_iommu_configure() allocates dev->iommu itself via
iommu_fwspec_init(), then suffers a DT parsing failure, it cleans up the
fwspec but leaves the empty dev_iommu hanging around. So far this is
benign (if a tiny bit wasteful), but we'd like to be able to reason
about dev->iommu having a consistent and unambiguous lifecycle. Thus
make sure that the of_iommu cleanup undoes precisely whatever it did.
Signed-off-by: Robin Murphy <robin.murphy at arm.com>
---
v2: New
drivers/iommu/iommu-priv.h | 2 ++
drivers/iommu/iommu.c | 2 +-
drivers/iommu/of_iommu.c | 6 +++++-
3 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/iommu-priv.h b/drivers/iommu/iommu-priv.h
index 17e245cf17bb..6574c1f97e14 100644
--- a/drivers/iommu/iommu-priv.h
+++ b/drivers/iommu/iommu-priv.h
@@ -17,6 +17,8 @@ static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
return dev->iommu->iommu_dev->ops;
}
+void dev_iommu_free(struct device *dev);
+
const struct iommu_ops *iommu_ops_from_fwnode(const struct fwnode_handle *fwnode);
static inline const struct iommu_ops *iommu_fwspec_ops(struct iommu_fwspec *fwspec)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 37b7088e129a..a3b45b84f42b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -352,7 +352,7 @@ static struct dev_iommu *dev_iommu_get(struct device *dev)
return param;
}
-static void dev_iommu_free(struct device *dev)
+void dev_iommu_free(struct device *dev)
{
struct dev_iommu *param = dev->iommu;
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 97987cd78da9..e10a68b5ffde 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -116,6 +116,7 @@ static void of_pci_check_device_ats(struct device *dev, struct device_node *np)
int of_iommu_configure(struct device *dev, struct device_node *master_np,
const u32 *id)
{
+ bool dev_iommu_present;
int err;
if (!master_np)
@@ -127,6 +128,7 @@ int of_iommu_configure(struct device *dev, struct device_node *master_np,
mutex_unlock(&iommu_probe_device_lock);
return 0;
}
+ dev_iommu_present = dev->iommu;
/*
* We don't currently walk up the tree looking for a parent IOMMU.
@@ -147,8 +149,10 @@ int of_iommu_configure(struct device *dev, struct device_node *master_np,
err = of_iommu_configure_device(master_np, dev, id);
}
- if (err)
+ if (err && dev_iommu_present)
iommu_fwspec_free(dev);
+ else if (err && dev->iommu)
+ dev_iommu_free(dev);
mutex_unlock(&iommu_probe_device_lock);
if (!err && dev->bus)
--
2.39.2.101.g768bb238c484.dirty
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