[PATCH 5/7] cgroups: Make freezer subsystem bindable

From: Li Zefan
Date: Fri Oct 22 2010 - 04:10:53 EST


To make it bindable, we need to thaw all processes when unbinding
the freezer subsystem from a cgroup hierarchy.

Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
---
include/linux/cgroup.h | 3 ++-
kernel/cgroup.c | 22 ++++++++++++++++++++--
kernel/cgroup_freezer.c | 19 +++++++++++++++++--
3 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 49369ff..1e4e1df 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -478,7 +478,8 @@ struct cgroup_subsys {
int (*populate)(struct cgroup_subsys *ss,
struct cgroup *cgrp);
void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
- void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
+ void (*bind)(struct cgroup_subsys *ss, struct cgroup *cgrp,
+ bool unbind);

int subsys_id;

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 6364bb5..12c1f7c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1105,6 +1105,22 @@ static int hierarchy_populate_dir(struct cgroup *cgrp, void *data)
return 0;
}

+static int hierarchy_subsys_bind(struct cgroup *cgrp, void *data)
+{
+ struct cgroup_subsys *ss = data;
+
+ ss->bind(ss, cgrp, false);
+ return 0;
+}
+
+static int hierarchy_subsys_unbind(struct cgroup *cgrp, void *data)
+{
+ struct cgroup_subsys *ss = data;;
+
+ ss->bind(ss, cgrp, true);
+ return 0;
+}
+
/*
* Call with cgroup_mutex held. Drops reference counts on modules, including
* any duplicate ones that parse_cgroupfs_options took. If this function
@@ -1172,7 +1188,8 @@ static int rebind_subsystems(struct cgroupfs_root *root,
list_move(&ss->sibling, &root->subsys_list);
ss->root = root;
if (ss->bind)
- ss->bind(ss, cgrp);
+ cgroup_walk_hierarchy(hierarchy_subsys_bind,
+ ss, cgrp);
mutex_unlock(&ss->hierarchy_mutex);
/* refcount was already taken, and we're keeping it */
} else if (bit & removed_bits) {
@@ -1180,7 +1197,8 @@ static int rebind_subsystems(struct cgroupfs_root *root,
BUG_ON(ss == NULL);
mutex_lock(&ss->hierarchy_mutex);
if (ss->bind)
- ss->bind(ss, dummytop);
+ cgroup_walk_hierarchy(hierarchy_subsys_unbind,
+ ss, cgrp);
subsys[i]->root = &rootnode;
list_move(&ss->sibling, &rootnode.subsys_list);
mutex_unlock(&ss->hierarchy_mutex);
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index e7bebb7..de13ce4 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -383,6 +383,21 @@ static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
}

+/*
+ * Thaw all processes before unbinding the freezer subsysem from
+ * cgroup hierarchy.
+ * */
+static void freezer_bind(struct cgroup_subsys *ss, struct cgroup *cgrp,
+ bool unbind)
+{
+ struct freezer *freezer = cgroup_freezer(cgrp);
+
+ if (!unbind)
+ return;
+
+ unfreeze_cgroup(cgrp, freezer);
+}
+
struct cgroup_subsys freezer_subsys = {
.name = "freezer",
.create = freezer_create,
@@ -390,7 +405,7 @@ struct cgroup_subsys freezer_subsys = {
.populate = freezer_populate,
.subsys_id = freezer_subsys_id,
.can_attach = freezer_can_attach,
- .attach = NULL,
.fork = freezer_fork,
- .exit = NULL,
+ .bind = freezer_bind,
+ .can_bind = 1,
};
--
1.7.0.1

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