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| author | Tejun Heo | 2012-11-09 18:12:29 +0100 |
|---|---|---|
| committer | Tejun Heo | 2012-11-09 18:12:29 +0100 |
| commit | a8638030f668884720b8f4456448d0ce33952b05 (patch) | |
| tree | 2532b2ef9def879513fad0e304a6a9c98fa798f0 /kernel/cgroup.c | |
| parent | cgroup: set 'start' with the right value in cgroup_path. (diff) | |
| download | kernel-qcow2-linux-a8638030f668884720b8f4456448d0ce33952b05.tar.gz kernel-qcow2-linux-a8638030f668884720b8f4456448d0ce33952b05.tar.xz kernel-qcow2-linux-a8638030f668884720b8f4456448d0ce33952b05.zip | |
cgroup: add cgroup_subsys->post_create()
Currently, there's no way for a controller to find out whether a new
cgroup finished all ->create() allocatinos successfully and is
considered "live" by cgroup.
This becomes a problem later when we add generic descendants walking
to cgroup which can be used by controllers as controllers don't have a
synchronization point where it can synchronize against new cgroups
appearing in such walks.
This patch adds ->post_create(). It's called after all ->create()
succeeded and the cgroup is linked into the generic cgroup hierarchy.
This plays the counterpart of ->pre_destroy().
When used in combination with the to-be-added generic descendant
iterators, ->post_create() can be used to implement reliable state
inheritance. It will be explained with the descendant iterators.
v2: Added a paragraph about its future use w/ descendant iterators per
Michal.
v3: Forgot to add ->post_create() invocation to cgroup_load_subsys().
Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Glauber Costa <glommer@parallels.com>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 998ab5957c6a..26f2edbaf4f5 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4059,10 +4059,15 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (err < 0) goto err_remove; - /* each css holds a ref to the cgroup's dentry */ - for_each_subsys(root, ss) + for_each_subsys(root, ss) { + /* each css holds a ref to the cgroup's dentry */ dget(dentry); + /* creation succeeded, notify subsystems */ + if (ss->post_create) + ss->post_create(cgrp); + } + /* The cgroup directory was pre-locked for us */ BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); @@ -4280,6 +4285,9 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) ss->active = 1; + if (ss->post_create) + ss->post_create(&ss->root->top_cgroup); + /* this function shouldn't be used with modular subsystems, since they * need to register a subsys_id, among other things */ BUG_ON(ss->module); @@ -4389,6 +4397,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) ss->active = 1; + if (ss->post_create) + ss->post_create(&ss->root->top_cgroup); + /* success! */ mutex_unlock(&cgroup_mutex); return 0; |