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Message-Id: <1248256822-23416-7-git-send-email-orenl@librato.com> Date: Wed, 22 Jul 2009 05:59:28 -0400 From: Oren Laadan <orenl@...rato.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Linus Torvalds <torvalds@...l.org>, containers@...ts.linux-foundation.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, linux-api@...r.kernel.org, Serge Hallyn <serue@...ibm.com>, Dave Hansen <dave@...ux.vnet.ibm.com>, Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>, Alexander Viro <viro@...iv.linux.org.uk>, Pavel Emelyanov <xemul@...nvz.org>, Alexey Dobriyan <adobriyan@...il.com>, Matt Helsley <matthltc@...ibm.com>, Oren Laadan <orenl@...columbia.edu>, Cedric Le Goater <legoater@...e.fr>, Paul Menage <menage@...gle.com>, Li Zefan <lizf@...fujitsu.com> Subject: [RFC v17][PATCH 06/60] cgroup freezer: Update stale locking comments From: Matt Helsley <matthltc@...ibm.com> 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 <matthltc@...ibm.com> Cc: Oren Laadan <orenl@...columbia.edu> Cc: Cedric Le Goater <legoater@...e.fr> Cc: Paul Menage <menage@...gle.com> Cc: Li Zefan <lizf@...fujitsu.com> --- 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@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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