On Wed, May 13, 2020 at 5:18 PM Heikki Krogerus <[email protected]> wrote: > > 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 <[email protected]> > Reported-by: kernel test robot <[email protected]> > Fixes: 7589238a8cf3 ("Revert "software node: Simplify software_node_release() > function"") > Cc: Brendan Higgins <[email protected]> > Cc: Randy Dunlap <[email protected]> > Suggested-by: "Rafael J. Wysocki" <[email protected]> > Signed-off-by: Heikki Krogerus <[email protected]>
Reviewed-by: Rafael J. Wysocki <[email protected]> > --- > lib/kobject.c | 30 ++++++++++++++++++++---------- > 1 file changed, 20 insertions(+), 10 deletions(-) > > diff --git a/lib/kobject.c b/lib/kobject.c > index 65fa7bf70c57..32432036bef8 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 >
