Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753016AbZIXAFF (ORCPT ); Wed, 23 Sep 2009 20:05:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752866AbZIXAEY (ORCPT ); Wed, 23 Sep 2009 20:04:24 -0400 Received: from smtp231.iad.emailsrvr.com ([207.97.245.231]:35609 "EHLO smtp231.iad.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752272AbZIXAES (ORCPT ); Wed, 23 Sep 2009 20:04:18 -0400 From: Oren Laadan To: Andrew Morton Cc: Linus Torvalds , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, Serge Hallyn , Ingo Molnar , Pavel Emelyanov , Matt Helsley , Oren Laadan , Cedric Le Goater , Paul Menage , Li Zefan Subject: [PATCH v18 06/80] cgroup freezer: Update stale locking comments Date: Wed, 23 Sep 2009 19:50:46 -0400 Message-Id: <1253749920-18673-7-git-send-email-orenl@librato.com> X-Mailer: git-send-email 1.6.0.4 In-Reply-To: <1253749920-18673-1-git-send-email-orenl@librato.com> References: <1253749920-18673-1-git-send-email-orenl@librato.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2822 Lines: 85 From: Matt Helsley Update stale comments regarding locking order and add a little more detail so it's easier to follow the locking between the cgroup freezer and the power management freezer code. Signed-off-by: Matt Helsley Cc: Oren Laadan Cc: Cedric Le Goater Cc: Paul Menage Cc: Li Zefan --- kernel/cgroup_freezer.c | 21 +++++++++++++-------- 1 files changed, 13 insertions(+), 8 deletions(-) diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index 765e2c1..22fce5d 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -88,10 +88,10 @@ struct cgroup_subsys freezer_subsys; /* Locks taken and their ordering * ------------------------------ - * css_set_lock * cgroup_mutex (AKA cgroup_lock) - * task->alloc_lock (AKA task_lock) * freezer->lock + * css_set_lock + * task->alloc_lock (AKA task_lock) * task->sighand->siglock * * cgroup code forces css_set_lock to be taken before task->alloc_lock @@ -99,33 +99,38 @@ struct cgroup_subsys freezer_subsys; * freezer_create(), freezer_destroy(): * cgroup_mutex [ by cgroup core ] * - * can_attach(): - * cgroup_mutex + * freezer_can_attach(): + * cgroup_mutex (held by caller of can_attach) * - * cgroup_frozen(): + * cgroup_freezing_or_frozen(): * task->alloc_lock (to get task's cgroup) * * freezer_fork() (preserving fork() performance means can't take cgroup_mutex): - * task->alloc_lock (to get task's cgroup) * freezer->lock * sighand->siglock (if the cgroup is freezing) * * freezer_read(): * cgroup_mutex * freezer->lock + * write_lock css_set_lock (cgroup iterator start) + * task->alloc_lock * read_lock css_set_lock (cgroup iterator start) * * freezer_write() (freeze): * cgroup_mutex * freezer->lock + * write_lock css_set_lock (cgroup iterator start) + * task->alloc_lock * read_lock css_set_lock (cgroup iterator start) - * sighand->siglock + * sighand->siglock (fake signal delivery inside freeze_task()) * * freezer_write() (unfreeze): * cgroup_mutex * freezer->lock + * write_lock css_set_lock (cgroup iterator start) + * task->alloc_lock * read_lock css_set_lock (cgroup iterator start) - * task->alloc_lock (to prevent races with freeze_task()) + * task->alloc_lock (inside thaw_process(), prevents race with refrigerator()) * sighand->siglock */ static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss, -- 1.6.0.4 -- 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/