The patch titled
cgroups: simplify init_subsys()
has been added to the -mm tree. Its filename is
cgroups-simplify-init_subsys.patch
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------------------------------------------------------
Subject: cgroups: simplify init_subsys()
From: Li Zefan <lizf@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Reviewed-by: Paul Menage <menage@xxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/cgroups.txt | 3 +--
kernel/cgroup.c | 35 +++++++++--------------------------
2 files changed, 10 insertions(+), 28 deletions(-)
diff -puN Documentation/cgroups.txt~cgroups-simplify-init_subsys Documentation/cgroups.txt
--- a/Documentation/cgroups.txt~cgroups-simplify-init_subsys
+++ a/Documentation/cgroups.txt
@@ -500,8 +500,7 @@ post-attachment activity that requires m
void fork(struct cgroup_subsy *ss, struct task_struct *task)
-Called when a task is forked into a cgroup. Also called during
-registration for all existing tasks.
+Called when a task is forked into a cgroup.
void exit(struct cgroup_subsys *ss, struct task_struct *task)
diff -puN kernel/cgroup.c~cgroups-simplify-init_subsys kernel/cgroup.c
--- a/kernel/cgroup.c~cgroups-simplify-init_subsys
+++ a/kernel/cgroup.c
@@ -2472,7 +2472,6 @@ static int cgroup_rmdir(struct inode *un
static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
{
struct cgroup_subsys_state *css;
- struct list_head *l;
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
@@ -2483,35 +2482,19 @@ static void __init cgroup_init_subsys(st
BUG_ON(IS_ERR(css));
init_cgroup_css(css, ss, dummytop);
- /* Update all cgroup groups to contain a subsys
+ /* Update the init_css_set to contain a subsys
* pointer to this state - since the subsystem is
- * newly registered, all tasks and hence all cgroup
- * groups are in the subsystem's top cgroup. */
- write_lock(&css_set_lock);
- l = &init_css_set.list;
- do {
- struct css_set *cg =
- list_entry(l, struct css_set, list);
- cg->subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
- l = l->next;
- } while (l != &init_css_set.list);
- write_unlock(&css_set_lock);
-
- /* If this subsystem requested that it be notified with fork
- * events, we should send it one now for every process in the
- * system */
- if (ss->fork) {
- struct task_struct *g, *p;
-
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- ss->fork(ss, p);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
- }
+ * newly registered, all tasks and hence the
+ * init_css_set is in the subsystem's top cgroup. */
+ init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
need_forkexit_callback |= ss->fork || ss->exit;
+ /* At system boot, before all subsystems have been
+ * registered, no tasks have been forked, so we don't
+ * need to invoke fork callbacks here. */
+ BUG_ON(!list_empty(&init_task.tasks));
+
ss->active = 1;
}
_
Patches currently in -mm which might be from lizf@xxxxxxxxxxxxxx are
cgroups-add-cgroup-support-for-enabling-controllers-at-boot-time.patch
ia64-use-goto-to-jump-out-do-while_each_thread.patch
sctp-fix-wrong-debug-counting-of-datamsg.patch
sctp-fix-wrong-debug-counting-of-bind_bucket.patch
cgroup-api-files-rename-read-write_uint-methods-to-read_write_u64.patch
cgroup-api-files-add-res_counter_read_u64.patch
cgroup-api-files-use-read_u64-in-memory-controller.patch
cgroup-api-files-strip-all-trailing-whitespace-in-cgroup_write_u64.patch
cgroup-api-files-update-cpusets-to-use-cgroup-structured-file-api.patch
cgroup-api-files-update-cpusets-to-use-cgroup-structured-file-api-fix.patch
cgroup-api-files-add-cgroup-map-data-type.patch
cgroup-api-files-use-cgroup-map-for-memcontrol-stats-file.patch
cgroup-api-files-drop-mem_cgroup_force_empty.patch
cgroup-api-files-move-releasable-to-cgroup_debug-subsystem.patch
cgroup-api-files-make-cgroup_debug-default-to-off.patch
cgroup-annotate-cgroup_init_subsys-with-__init.patch
cgroup-switch-to-proc_create.patch
cgroups-implement-device-whitelist-v6.patch
cgroups-implement-device-whitelist-v6-checkpatch-fixes.patch
cgroups-implement-device-whitelist-v6-cleanups.patch
cgroups-implement-device-whitelist-doc.patch
cgroups-implement-device-whitelist-v6-fix.patch
cgroups-use-a-hash-table-for-css_set-finding.patch
cgroups-simplify-init_subsys.patch
cgroups-remove-the-css_set-linked-list.patch
add-a-document-describing-the-resource-counter-abstraction-v2-fix.patch
cpuset-hardwall-flag-switch-cpusets-to-use-the-bulk-cgroup_add_files-api.patch
--
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