[PATCH 1/9] cgroup: add cgroup_subsys->post_create()
From: Tejun Heo <hidden>
Date: 2012-11-03 08:39:11
Also in:
linux-pm, lkml
Subsystem:
control group (cgroup), the rest · Maintainers:
Tejun Heo, Johannes Weiner, Michal Koutný, Linus Torvalds
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(). Signed-off-by: Tejun Heo <redacted> Cc: Glauber Costa <redacted> --- include/linux/cgroup.h | 1 + kernel/cgroup.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index fe876a7..b442122 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h@@ -438,6 +438,7 @@ int cgroup_taskset_size(struct cgroup_taskset *tset); struct cgroup_subsys { struct cgroup_subsys_state *(*create)(struct cgroup *cgrp); + void (*post_create)(struct cgroup *cgrp); void (*pre_destroy)(struct cgroup *cgrp); void (*destroy)(struct cgroup *cgrp); int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e3045ad..f05d992 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c@@ -4060,10 +4060,15 @@ 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));
@@ -4281,6 +4286,9 @@ 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);
--
1.7.11.7