iommu: Unexport iommu_fwspec_free()

The drivers doing their own fwspec parsing have no need to call
iommu_fwspec_free() since fwspecs were moved into dev_iommu, as
returning an error from .probe_device will tear down the whole lot
anyway. Move it into the private interface now that it only serves
for of_iommu to clean up in an error case.

I have no idea what mtk_v1 was doing in effectively guaranteeing
a NULL fwspec would be dereferenced if no "iommus" DT property was
found, so add a check for that to at least make the code look sane.

Signed-off-by: Robin Murphy <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Link: https://lore.kernel.org/r/36e245489361de2d13db22a510fa5c79e7126278.1740667667.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <[email protected]>

Author: rmurphy-arm

drivers/iommu/arm/arm-smmu/arm-smmu.c

@@ -1486,7 +1486,6 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 out_cfg_free:
 	kfree(cfg);
 out_free:
-	iommu_fwspec_free(dev);
 	return ERR_PTR(ret);
 }
 

drivers/iommu/iommu-priv.h

@@ -24,6 +24,8 @@ static inline const struct iommu_ops *iommu_fwspec_ops(struct iommu_fwspec *fwsp
 	return iommu_ops_from_fwnode(fwspec ? fwspec->iommu_fwnode : NULL);
 }
 
+void iommu_fwspec_free(struct device *dev);
+
 int iommu_device_register_bus(struct iommu_device *iommu,
 			      const struct iommu_ops *ops,
 			      const struct bus_type *bus,

drivers/iommu/iommu.c

@@ -2837,7 +2837,6 @@ void iommu_fwspec_free(struct device *dev)
 		dev_iommu_fwspec_set(dev, NULL);
 	}
 }
-EXPORT_SYMBOL_GPL(iommu_fwspec_free);
 
 int iommu_fwspec_add_ids(struct device *dev, const u32 *ids, int num_ids)
 {

drivers/iommu/mtk_iommu_v1.c

@@ -446,22 +446,13 @@ static int mtk_iommu_v1_create_mapping(struct device *dev,
 
 static struct iommu_device *mtk_iommu_v1_probe_device(struct device *dev)
 {
-	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct iommu_fwspec *fwspec = NULL;
 	struct of_phandle_args iommu_spec;
 	struct mtk_iommu_v1_data *data;
 	int err, idx = 0, larbid, larbidx;
 	struct device_link *link;
 	struct device *larbdev;
 
-	/*
-	 * In the deferred case, free the existed fwspec.
-	 * Always initialize the fwspec internally.
-	 */
-	if (fwspec) {
-		iommu_fwspec_free(dev);
-		fwspec = dev_iommu_fwspec_get(dev);
-	}
-
 	while (!of_parse_phandle_with_args(dev->of_node, "iommus",
 					   "#iommu-cells",
 					   idx, &iommu_spec)) {
@@ -476,6 +467,9 @@ static struct iommu_device *mtk_iommu_v1_probe_device(struct device *dev)
 		idx++;
 	}
 
+	if (!fwspec)
+		return ERR_PTR(-ENODEV);
+
 	data = dev_iommu_priv_get(dev);
 
 	/* Link the consumer device with the smi-larb device(supplier) */

drivers/iommu/tegra-smmu.c

@@ -846,7 +846,6 @@ static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev,
 	err = ops->of_xlate(dev, args);
 	if (err < 0) {
 		dev_err(dev, "failed to parse SW group ID: %d\n", err);
-		iommu_fwspec_free(dev);
 		return err;
 	}
 

include/linux/iommu.h

@@ -1099,7 +1099,6 @@ struct iommu_mm_data {
 };
 
 int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode);
-void iommu_fwspec_free(struct device *dev);
 int iommu_fwspec_add_ids(struct device *dev, const u32 *ids, int num_ids);
 
 static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev)
@@ -1410,10 +1409,6 @@ static inline int iommu_fwspec_init(struct device *dev,
 	return -ENODEV;
 }
 
-static inline void iommu_fwspec_free(struct device *dev)
-{
-}
-
 static inline int iommu_fwspec_add_ids(struct device *dev, u32 *ids,
 				       int num_ids)
 {