This is a note to let you know that I've just added the patch titled
kobject: Make sure the parent does not get released before its
to my driver-core git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 4ef12f7198023c09ad6d25b652bd8748c965c7fa Mon Sep 17 00:00:00 2001
From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Date: Wed, 13 May 2020 18:18:40 +0300
Subject: kobject: Make sure the parent does not get released before its
children
In the function kobject_cleanup(), kobject_del(kobj) is
called before the kobj->release(). That makes it possible to
release the parent of the kobject before the kobject itself.
To fix that, adding function __kboject_del() that does
everything that kobject_del() does except release the parent
reference. kobject_cleanup() then calls __kobject_del()
instead of kobject_del(), and separately decrements the
reference count of the parent kobject after kobj->release()
has been called.
Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx>
Fixes: 7589238a8cf3 ("Revert "software node: Simplify software_node_release() function"")
Suggested-by: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
Tested-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200513151840.36400-1-heikki.krogerus@xxxxxxxxxxxxxxx
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
lib/kobject.c | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)
diff --git a/lib/kobject.c b/lib/kobject.c
index 83198cb37d8d..2bd631460e18 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -599,14 +599,7 @@ int kobject_move(struct kobject *kobj, struct kobject *new_parent)
}
EXPORT_SYMBOL_GPL(kobject_move);
-/**
- * kobject_del() - Unlink kobject from hierarchy.
- * @kobj: object.
- *
- * This is the function that should be called to delete an object
- * successfully added via kobject_add().
- */
-void kobject_del(struct kobject *kobj)
+static void __kobject_del(struct kobject *kobj)
{
struct kernfs_node *sd;
const struct kobj_type *ktype;
@@ -625,9 +618,23 @@ void kobject_del(struct kobject *kobj)
kobj->state_in_sysfs = 0;
kobj_kset_leave(kobj);
- kobject_put(kobj->parent);
kobj->parent = NULL;
}
+
+/**
+ * kobject_del() - Unlink kobject from hierarchy.
+ * @kobj: object.
+ *
+ * This is the function that should be called to delete an object
+ * successfully added via kobject_add().
+ */
+void kobject_del(struct kobject *kobj)
+{
+ struct kobject *parent = kobj->parent;
+
+ __kobject_del(kobj);
+ kobject_put(parent);
+}
EXPORT_SYMBOL(kobject_del);
/**
@@ -663,6 +670,7 @@ EXPORT_SYMBOL(kobject_get_unless_zero);
*/
static void kobject_cleanup(struct kobject *kobj)
{
+ struct kobject *parent = kobj->parent;
struct kobj_type *t = get_ktype(kobj);
const char *name = kobj->name;
@@ -684,7 +692,7 @@ static void kobject_cleanup(struct kobject *kobj)
if (kobj->state_in_sysfs) {
pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n",
kobject_name(kobj), kobj);
- kobject_del(kobj);
+ __kobject_del(kobj);
}
if (t && t->release) {
@@ -698,6 +706,8 @@ static void kobject_cleanup(struct kobject *kobj)
pr_debug("kobject: '%s': free name\n", name);
kfree_const(name);
}
+
+ kobject_put(parent);
}
#ifdef CONFIG_DEBUG_KOBJECT_RELEASE
--
2.26.2
