Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932193AbbLNTDO (ORCPT ); Mon, 14 Dec 2015 14:03:14 -0500 Received: from mail-pa0-f44.google.com ([209.85.220.44]:35304 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932086AbbLNTDN (ORCPT ); Mon, 14 Dec 2015 14:03:13 -0500 From: Rajat Jain To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Cc: linux-pci@vger.kernel.com, rajatxjain@gmail.com, Rajat Jain Subject: [PATCH] kobject: Ensure child's resources get released before parent's resources Date: Mon, 14 Dec 2015 11:02:46 -0800 Message-Id: <1450119766-28102-1-git-send-email-rajatja@google.com> X-Mailer: git-send-email 2.6.0.rc2.230.g3dd15c0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2089 Lines: 64 If the only remaining reference to a parent, is the one taken by the child (in kobject_add_internal()), then when the last reference to the child goes away, both child and its parents shall be released. However, currently the resources of parent get released first, followed by the child's resources: kobject_cleanup(child) .... kobject_del(child) .... kobject_put(child->parent) -> results in parent's release() ... child->kobj_type->release() -> Child's release() This is a problem because the child's release() method may still need to use parent resources or memory for its own cleanup. E.g. child may need parent pointer for dma_free_coherent() etc. Signed-off-by: Rajat Jain Signed-off-by: Rajat Jain --- resending after an email address that bounced. lib/kobject.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/lib/kobject.c b/lib/kobject.c index 7cbccd2..8f325ac 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -616,6 +616,7 @@ static void kobject_cleanup(struct kobject *kobj) { struct kobj_type *t = get_ktype(kobj); const char *name = kobj->name; + struct kobject *parent = kobj->parent; pr_debug("kobject: '%s' (%p): %s, parent %p\n", kobject_name(kobj), kobj, __func__, kobj->parent); @@ -632,6 +633,8 @@ static void kobject_cleanup(struct kobject *kobj) kobject_uevent(kobj, KOBJ_REMOVE); } + kobject_get(parent); + /* remove from sysfs if the caller did not do it */ if (kobj->state_in_sysfs) { pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n", @@ -645,6 +648,8 @@ static void kobject_cleanup(struct kobject *kobj) t->release(kobj); } + kobject_put(parent); + /* free name if we allocated it */ if (name) { pr_debug("kobject: '%s': free name\n", name); -- 2.6.0.rc2.230.g3dd15c0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/