[PATCH v2 5/9] iommu/of: Take a ref to the IOMMU driver during ->of_xlate()

Will Deacon
2019-11-08T15:16:32Z

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 {