[PATCH 11/14] cgroup: use CSS_ONLINE instead of CGRP_DEAD

Tejun Heo
2014-05-09T21:33:28Z

Use CSS_ONLINE on the self css to indicate whether a cgroup has been
killed instead of CGRP_DEAD. This will allow re-using css online test
for cgroup liveliness test. This doesn't introduce any functional
change.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
include/linux/cgroup.h | 2 --
kernel/cgroup.c | 7 ++++---
2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 58867ed..2cf2063 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -138,8 +138,6 @@ static inline void css_put(struct cgroup_subsys_state *css)

/* bits in struct cgroup flags field */
enum {
- /* Control Group is dead */
- CGRP_DEAD,
/*
* Control Group has previously had a child cgroup or a task,
* but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e0953f7..a0cfe36 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -278,7 +278,7 @@ static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
/* convenient tests for these bits */
static inline bool cgroup_is_dead(const struct cgroup *cgrp)
{
- return test_bit(CGRP_DEAD, &cgrp->flags);
+ return !(cgrp->self.flags & CSS_ONLINE);
}

struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
@@ -1518,6 +1518,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
cgrp->self.cgroup = cgrp;
+ cgrp->self.flags |= CSS_ONLINE;

for_each_subsys(ss, ssid)
INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
@@ -4540,13 +4541,13 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
* Mark @cgrp dead. This prevents further task migration and child
* creation by disabling cgroup_lock_live_group().
*/
- set_bit(CGRP_DEAD, &cgrp->flags);
+ cgrp->self.flags &= ~CSS_ONLINE;

/* initiate massacre of all css's */
for_each_css(css, ssid, cgrp)
kill_css(css);

- /* CGRP_DEAD is set, remove from ->release_list for the last time */
+ /* CSS_ONLINE is clear, remove from ->release_list for the last time */
raw_spin_lock(&release_list_lock);
if (!list_empty(&cgrp->release_list))
list_del_init(&cgrp->release_list);
--
1.9.0