Commit 5ab894ae authored Oct 09, 2017 by Jarkko Nikula Committed by Rafael J. Wysocki Oct 10, 2017

device property: Track owner device of device property



Deletion of subdevice will remove device properties associated to parent
when they share the same firmware node after commit 478573c9 (driver
core: Don't leak secondary fwnode on device removal).  This was observed
with a driver adding subdevice that driver wasn't able to read device
properties after rmmod/modprobe cycle.

Consider the lifecycle of it:

parent device registration
	ACPI_COMPANION_SET()
	device_add_properties()
		pset_copy_set()
		set_secondary_fwnode(dev, &p->fwnode)
	device_add()

parent probe
	read device properties
	ACPI_COMPANION_SET(subdevice, ACPI_COMPANION(parent))
	device_add(subdevice)

parent remove
	device_del(subdevice)
		device_remove_properties()
			set_secondary_fwnode(dev, NULL);
			pset_free()

Parent device will have its primary firmware node pointing to an ACPI
node and secondary firmware node point to device properties.

ACPI_COMPANION_SET() call in parent probe will set the subdevice's
firmware node to point to the same 'struct fwnode_handle' and the
associated secondary firmware node, i.e. the device properties as the
parent.

When subdevice is deleted in parent remove that will remove those
device properties and attempt to read device properties in next
parent probe call will fail.

Fix this by tracking the owner device of device properties and delete
them only when owner device is being deleted.

Fixes: 478573c9 (driver core: Don't leak secondary fwnode on device removal)
Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 8a5776a5

drivers/base/property.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@
		#include <linux/phy.h>

		struct property_set {
		struct device *dev;
		struct fwnode_handle fwnode;
		const struct property_entry *properties;
		};
		@@ -891,6 +892,7 @@ static struct property_set pset_copy_set(const struct property_set pset)
		void device_remove_properties(struct device *dev)
		{
		struct fwnode_handle *fwnode;
		struct property_set *pset;

		fwnode = dev_fwnode(dev);
		if (!fwnode)
		@@ -900,16 +902,16 @@ void device_remove_properties(struct device *dev)
		* the pset. If there is no real firmware node (ACPI/DT) primary
		* will hold the pset.
		*/
		if (is_pset_node(fwnode)) {
		pset = to_pset_node(fwnode);
		if (pset) {
		set_primary_fwnode(dev, NULL);
		pset_free_set(to_pset_node(fwnode));
		} else {
		fwnode = fwnode->secondary;
		if (!IS_ERR(fwnode) && is_pset_node(fwnode)) {
		pset = to_pset_node(fwnode->secondary);
		if (pset && dev == pset->dev)
		set_secondary_fwnode(dev, NULL);
		pset_free_set(to_pset_node(fwnode));
		}
		}
		if (pset && dev == pset->dev)
		pset_free_set(pset);
		}
		EXPORT_SYMBOL_GPL(device_remove_properties);

		@@ -938,6 +940,7 @@ int device_add_properties(struct device *dev,

		p->fwnode.ops = &pset_fwnode_ops;
		set_secondary_fwnode(dev, &p->fwnode);
		p->dev = dev;
		return 0;
		}
		EXPORT_SYMBOL_GPL(device_add_properties);

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