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authorLi Zefan <lizf@cn.fujitsu.com>2008-04-29 04:00:13 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 11:06:10 -0400
commite8d55fdeb882cfcb5e8db5a5ce16edfba78aafc5 (patch)
tree0c0a7338d8adb2aaf4310eb89d1679c802ea617d /kernel
parent472b1053f3c319cc60bfb2a0bb062fed77a93eb6 (diff)
cgroups: simplify init_subsys()
We are at system boot and there is only 1 cgroup group (i,e, init_css_set), so we don't need to run through the css_set linked list. Neither do we need to run through the task list, since no processes have been created yet. Also referring to a comment in cgroup.h: struct css_set { ... /* * Set of subsystem states, one for each subsystem. This array * is immutable after creation apart from the init_css_set * during subsystem registration (at boot time). */ struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; } Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c35
1 files changed, 9 insertions, 26 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c447c29f8749..b893c8c94858 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2477,7 +2477,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
2477static void __init cgroup_init_subsys(struct cgroup_subsys *ss) 2477static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
2478{ 2478{
2479 struct cgroup_subsys_state *css; 2479 struct cgroup_subsys_state *css;
2480 struct list_head *l;
2481 2480
2482 printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); 2481 printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
2483 2482
@@ -2488,35 +2487,19 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
2488 BUG_ON(IS_ERR(css)); 2487 BUG_ON(IS_ERR(css));
2489 init_cgroup_css(css, ss, dummytop); 2488 init_cgroup_css(css, ss, dummytop);
2490 2489
2491 /* Update all cgroup groups to contain a subsys 2490 /* Update the init_css_set to contain a subsys
2492 * pointer to this state - since the subsystem is 2491 * pointer to this state - since the subsystem is
2493 * newly registered, all tasks and hence all cgroup 2492 * newly registered, all tasks and hence the
2494 * groups are in the subsystem's top cgroup. */ 2493 * init_css_set is in the subsystem's top cgroup. */
2495 write_lock(&css_set_lock); 2494 init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
2496 l = &init_css_set.list;
2497 do {
2498 struct css_set *cg =
2499 list_entry(l, struct css_set, list);
2500 cg->subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
2501 l = l->next;
2502 } while (l != &init_css_set.list);
2503 write_unlock(&css_set_lock);
2504
2505 /* If this subsystem requested that it be notified with fork
2506 * events, we should send it one now for every process in the
2507 * system */
2508 if (ss->fork) {
2509 struct task_struct *g, *p;
2510
2511 read_lock(&tasklist_lock);
2512 do_each_thread(g, p) {
2513 ss->fork(ss, p);
2514 } while_each_thread(g, p);
2515 read_unlock(&tasklist_lock);
2516 }
2517 2495
2518 need_forkexit_callback |= ss->fork || ss->exit; 2496 need_forkexit_callback |= ss->fork || ss->exit;
2519 2497
2498 /* At system boot, before all subsystems have been
2499 * registered, no tasks have been forked, so we don't
2500 * need to invoke fork callbacks here. */
2501 BUG_ON(!list_empty(&init_task.tasks));
2502
2520 ss->active = 1; 2503 ss->active = 1;
2521} 2504}
2522 2505