lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Freezer / cgroup freezer: Update stale locking comments

Browse Source 
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@us.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This commit is contained in:
Matt Helsley
2010-05-10 23:18:47 +02:00
committed by Rafael J. Wysocki
parent 543f2503a9
commit 8f77578cc2
1 changed files with 13 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/cgroup_freezer.c
View File

@@ -89,10 +89,10 @@ struct cgroup_subsys freezer_subsys;
/* Locks taken and their ordering /* Locks taken and their ordering
* ------------------------------ * ------------------------------
* css_set_lock
* cgroup_mutex (AKA cgroup_lock) * cgroup_mutex (AKA cgroup_lock)
* task->alloc_lock (AKA task_lock)
* freezer->lock * freezer->lock
* css_set_lock
* task->alloc_lock (AKA task_lock)
* task->sighand->siglock * task->sighand->siglock
* *
* cgroup code forces css_set_lock to be taken before task->alloc_lock * 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(): * freezer_create(), freezer_destroy():
* cgroup_mutex [ by cgroup core ] * cgroup_mutex [ by cgroup core ]
* *
* can_attach(): * freezer_can_attach():
* cgroup_mutex * cgroup_mutex (held by caller of can_attach)
* *
* cgroup_frozen(): * cgroup_freezing_or_frozen():
* task->alloc_lock (to get task's cgroup) * task->alloc_lock (to get task's cgroup)
* *
* freezer_fork() (preserving fork() performance means can't take cgroup_mutex): * freezer_fork() (preserving fork() performance means can't take cgroup_mutex):
* task->alloc_lock (to get task's cgroup)
* freezer->lock * freezer->lock
* sighand->siglock (if the cgroup is freezing) * sighand->siglock (if the cgroup is freezing)
* *
* freezer_read(): * freezer_read():
* cgroup_mutex * cgroup_mutex
* freezer->lock * freezer->lock
* write_lock css_set_lock (cgroup iterator start)
* task->alloc_lock
* read_lock css_set_lock (cgroup iterator start) * read_lock css_set_lock (cgroup iterator start)
* *
* freezer_write() (freeze): * freezer_write() (freeze):
* cgroup_mutex * cgroup_mutex
* freezer->lock * freezer->lock
* write_lock css_set_lock (cgroup iterator start)
* task->alloc_lock
* read_lock css_set_lock (cgroup iterator start) * read_lock css_set_lock (cgroup iterator start)
* sighand->siglock * sighand->siglock (fake signal delivery inside freeze_task())
* *
* freezer_write() (unfreeze): * freezer_write() (unfreeze):
* cgroup_mutex * cgroup_mutex
* freezer->lock * freezer->lock
* write_lock css_set_lock (cgroup iterator start)
* task->alloc_lock
* read_lock css_set_lock (cgroup iterator start) * 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 * sighand->siglock
*/ */
static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss, static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,