Patch "device property: Track owner device of device property" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

device property: Track owner device of device property

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
device-property-track-owner-device-of-device-property.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jarkko Nikula <[email protected]>
Date: Mon, 9 Oct 2017 16:28:37 +0300
Subject: device property: Track owner device of device property

From: Jarkko Nikula <[email protected]>

commit 5ab894aee0f171a682bcd90dd5d1930cb53c55dc upstream.

Deletion of subdevice will remove device properties associated to parent when they share the same firmware node after commit 478573c93abd (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.

---
 drivers/base/property.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

@@ -21,6 +21,7 @@
 #include <linux/phy.h>
 
 struct property_set {
+	struct device *dev;
 	struct fwnode_handle fwnode;
 	const struct property_entry *properties;
 };

@@ -855,6 +856,7 @@ static struct property_set *pset_copy_se
 void device_remove_properties(struct device *dev)
 {
 	struct fwnode_handle *fwnode;
+	struct property_set *pset;
 
 	fwnode = dev_fwnode(dev);
 	if (!fwnode)

@@ -864,16 +866,16 @@ void device_remove_properties(struct 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);
 

@@ -903,6 +905,7 @@ int device_add_properties(struct device
 	p->fwnode.type = FWNODE_PDATA;
 	p->fwnode.ops = &pset_fwnode_ops;
 	set_secondary_fwnode(dev, &p->fwnode);
+	p->dev = dev;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(device_add_properties);

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/device-property-track-owner-device-of-device-property.patch