From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor2.suse.de ([195.135.220.15]:51725 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751979Ab3IPSWS (ORCPT ); Mon, 16 Sep 2013 14:22:18 -0400 Message-Id: <20130916182018.120725897@suse.com> Date: Mon, 16 Sep 2013 14:19:13 -0400 From: Jeff Mahoney To: linux-btrfs@vger.kernel.org Cc: dsterba@suse.cz, clmason@fusionio.com Subject: [patch 3/9] kobject: introduce kobj_completion References: <20130916181910.799140428@suse.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: A common way to handle kobject lifetimes in embedded in objects with different lifetime rules is to pair the kobject with a struct completion. This introduces a kobj_completion structure that can be used in place of the pairing, along with several convenience functions for initialization, release, and put-and-wait. Signed-off-by: Jeff Mahoney --- include/linux/kobj_completion.h | 18 ++++++++++++++ lib/kobject.c | 50 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+) --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ b/include/linux/kobj_completion.h 2013-09-10 12:58:03.530554144 -0400 @@ -0,0 +1,18 @@ +#ifndef _KOBJ_COMPLETION_H_ +#define _KOBJ_COMPLETION_H_ + +#include +#include + +struct kobj_completion { + struct kobject kc_kobj; + struct completion kc_unregister; +}; + +#define kobj_to_kobj_completion(kobj) \ + container_of(kobj, struct kobj_completion, kc_kobj) + +void kobj_completion_init(struct kobj_completion *kc, struct kobj_type *ktype); +void kobj_completion_release(struct kobject *kobj); +void kobj_completion_del_and_wait(struct kobj_completion *kc); +#endif /* _KOBJ_COMPLETION_H_ */ --- a/lib/kobject.c 2013-09-10 12:57:54.198666613 -0400 +++ b/lib/kobject.c 2013-09-10 15:22:15.122724060 -0400 @@ -13,6 +13,7 @@ */ #include +#include #include #include #include @@ -711,6 +712,55 @@ const struct sysfs_ops kobj_sysfs_ops = }; /** + * kobj_completion_init - initialize a kobj_completion object. + * @kc: kobj_completion + * @ktype: type of kobject to initialize + * + * kobj_completion structures can be embedded within structures with different + * lifetime rules. During the release of the enclosing object, we can + * wait on the release of the kobject so that we don't free it while it's + * still busy. + */ +void kobj_completion_init(struct kobj_completion *kc, struct kobj_type *ktype) +{ + init_completion(&kc->kc_unregister); + kobject_init(&kc->kc_kobj, ktype); +} +EXPORT_SYMBOL_GPL(kobj_completion_init); + +/** + * kobj_completion_release - release a kobj_completion object + * @kobj: kobject embedded in kobj_completion + * + * Used with kobject_release to notify waiters that the kobject has been + * released. + */ +void kobj_completion_release(struct kobject *kobj) +{ + struct kobj_completion *kc = kobj_to_kobj_completion(kobj); + complete(&kc->kc_unregister); +} +EXPORT_SYMBOL_GPL(kobj_completion_release); + +/** + * kobj_completion_del_and_wait - release the kobject and wait for it + * @kc: kobj_completion object to release + * + * Delete the kobject from sysfs and drop the reference count. Then wait + * until any other outstanding references are also dropped. This routine + * is only necessary once other references may have been taken on the + * kobject. Typically this happens when the kobject has been published + * to sysfs via kobject_add. + */ +void kobj_completion_del_and_wait(struct kobj_completion *kc) +{ + kobject_del(&kc->kc_kobj); + kobject_put(&kc->kc_kobj); + wait_for_completion(&kc->kc_unregister); +} +EXPORT_SYMBOL_GPL(kobj_completion_del_and_wait); + +/** * kset_register - initialize and add a kset. * @k: kset. */