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

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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: Alan Tull <atull@kernel.org>
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
This commit is contained in:
Frank Rowand 2018-10-04 20:24:17 -07:00
parent 651022382c
commit 144552c786
3 changed files with 40 additions and 5 deletions
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29
drivers/of/dynamic.c
View File

@ -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);

1
drivers/of/overlay.c
View File

@ -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)

15
include/linux/of.h
View File

@ -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)