On Saturday 01 May 2010, Oren Laadan wrote: > From: Matt Helsley <matthltc@xxxxxxxxxx> > > 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. I guess these three patches are for me. Do you want me to handle them? Rafael > Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx> > Cc: Oren Laadan <orenl@xxxxxxxxxxxxxxx> > Cc: Cedric Le Goater <legoater@xxxxxxx> > Cc: Paul Menage <menage@xxxxxxxxxx> > Cc: Li Zefan <lizf@xxxxxxxxxxxxxx> > Cc: Rafael J. Wysocki <rjw@xxxxxxx> > Cc: linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx > --- > 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 da5e139..85f19cc 100644 > --- a/kernel/cgroup_freezer.c > +++ b/kernel/cgroup_freezer.c > @@ -89,10 +89,10 @@ 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 > @@ -100,33 +100,38 @@ 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, > _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
