Commit 144552c7 authored by Frank Rowand's avatar Frank Rowand
Browse files

of: overlay: add tests to validate kfrees from overlay removal 



Add checks:
  - attempted kfree due to refcount reaching zero before overlay
    is removed
  - properties linked to an overlay node when the node is removed
  - node refcount > one during node removal in a changeset destroy,
    if the node was created by the changeset

After applying this patch, several validation warnings will be
reported from the devicetree unittest during boot due to
pre-existing devicetree bugs. The warnings will be similar to:

  OF: ERROR: of_node_release(), unexpected properties in /testcase-data/overlay-node/test-bus/test-unittest11
  OF: ERROR: memory leak, expected refcount 1 instead of 2, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node /testcase-data-2/substation@100/
  hvac-medium-2

Tested-by: default avatarAlan Tull <atull@kernel.org>
Signed-off-by: default avatarFrank Rowand <frank.rowand@sony.com>
parent 65102238

drivers/of/dynamic.c

+29 −0
Original line number Diff line number Diff line
@@ -330,6 +330,25 @@ void of_node_release(struct kobject *kobj) 
	if (!of_node_check_flag(node, OF_DYNAMIC))

		return;



	if (of_node_check_flag(node, OF_OVERLAY)) {



		if (!of_node_check_flag(node, OF_OVERLAY_FREE_CSET)) {

			/* premature refcount of zero, do not free memory */

			pr_err("ERROR: memory leak before free overlay changeset,  %pOF\n",

			       node);

			return;

		}



		/*

		 * If node->properties non-empty then properties were added

		 * to this node either by different overlay that has not

		 * yet been removed, or by a non-overlay mechanism.

		 */

		if (node->properties)

			pr_err("ERROR: %s(), unexpected properties in %pOF\n",

			       __func__, node);

	}



	property_list_free(node->properties);

	property_list_free(node->deadprops);
@@ -434,6 +453,16 @@ struct device_node *__of_node_dup(const struct device_node *np, 


static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)

{

	if (ce->action == OF_RECONFIG_ATTACH_NODE &&

	    of_node_check_flag(ce->np, OF_OVERLAY)) {

		if (kref_read(&ce->np->kobj.kref) > 1) {

			pr_err("ERROR: memory leak, expected refcount 1 instead of %d, of_node_get()/of_node_put() unbalanced - destroy cset entry: attach overlay node %pOF\n",

			       kref_read(&ce->np->kobj.kref), ce->np);

		} else {

			of_node_set_flag(ce->np, OF_OVERLAY_FREE_CSET);

		}

	}



	of_node_put(ce->np);

	list_del(&ce->node);

	kfree(ce);

drivers/of/overlay.c

+1 −0
Original line number Diff line number Diff line
@@ -373,6 +373,7 @@ static int add_changeset_node(struct overlay_changeset *ovcs, 
			return -ENOMEM;



		tchild->parent = target_node;

		of_node_set_flag(tchild, OF_OVERLAY);



		ret = of_changeset_attach_node(&ovcs->cset, tchild);

		if (ret)

include/linux/of.h

+10 −5
Original line number Diff line number Diff line
@@ -138,11 +138,16 @@ extern struct device_node *of_aliases; 
extern struct device_node *of_stdout;

extern raw_spinlock_t devtree_lock;



/* flag descriptions (need to be visible even when !CONFIG_OF) */

#define OF_DYNAMIC	1 /* node and properties were allocated via kmalloc */

#define OF_DETACHED	2 /* node has been detached from the device tree */

#define OF_POPULATED	3 /* device already created for the node */

#define OF_POPULATED_BUS	4 /* of_platform_populate recursed to children of this node */

/*

 * struct device_node flag descriptions

 * (need to be visible even when !CONFIG_OF)

 */

#define OF_DYNAMIC		1 /* (and properties) allocated via kmalloc */

#define OF_DETACHED		2 /* detached from the device tree */

#define OF_POPULATED		3 /* device already created */

#define OF_POPULATED_BUS	4 /* platform bus created for children */

#define OF_OVERLAY		5 /* allocated for an overlay */

#define OF_OVERLAY_FREE_CSET	6 /* in overlay cset being freed */



#define OF_BAD_ADDR	((u64)-1)

CRA Git | Maintained and supported by SUSTech CRA and CCSE