Currently we use a global work to schedule release agent on removable
cgroups. We can change to reuse css->destroy_work to do this, which
saves a few lines of code.
Signed-off-by: Zefan Li
---
include/linux/cgroup.h | 7
kernel/cgroup.c| 108 ++---
2 files changed, 39 insertions(+), 76 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f7898e0..97da407 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -234,13 +234,6 @@ struct cgroup {
struct list_head e_csets[CGROUP_SUBSYS_COUNT];
/*
-* Linked list running through all cgroups that can
-* potentially be reaped by the release agent. Protected by
-* release_list_lock
-*/
- struct list_head release_list;
-
- /*
* list of pidlists, up to two for each namespace (one for procs, one
* for tasks); created on demand.
*/
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1abb554..5b6566c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -392,12 +392,7 @@ static int notify_on_release(const struct cgroup *cgrp)
; \
else
-/* the list of cgroups eligible for automatic release. Protected by
- * release_list_lock */
-static LIST_HEAD(release_list);
-static DEFINE_RAW_SPINLOCK(release_list_lock);
static void cgroup_release_agent(struct work_struct *work);
-static DECLARE_WORK(release_agent_work, cgroup_release_agent);
static void check_for_release(struct cgroup *cgrp);
/*
@@ -1577,7 +1572,6 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->self.sibling);
INIT_LIST_HEAD(&cgrp->self.children);
INIT_LIST_HEAD(&cgrp->cset_links);
- INIT_LIST_HEAD(&cgrp->release_list);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
cgrp->self.cgroup = cgrp;
@@ -1587,6 +1581,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
init_waitqueue_head(&cgrp->offline_waitq);
+ INIT_WORK(&cgrp->self.destroy_work, cgroup_release_agent);
}
static void init_cgroup_root(struct cgroup_root *root,
@@ -4804,12 +4799,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
for_each_css(css, ssid, cgrp)
kill_css(css);
- /* 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);
- raw_spin_unlock(&release_list_lock);
-
/*
* Remove @cgrp directory along with the base files. @cgrp has an
* extra ref on its kn.
@@ -5274,21 +5263,14 @@ static void check_for_release(struct cgroup *cgrp)
if (cgroup_is_releasable(cgrp) && list_empty(&cgrp->cset_links) &&
!css_has_online_children(&cgrp->self)) {
/*
-* Control Group is currently removeable. If it's not
-* already queued for a userspace notification, queue
-* it now
+* get a reference, so the cgroup can only be freed
+* after the release work is done.
*/
- int need_schedule_work = 0;
+ if (!cgroup_tryget(cgrp))
+ return;
- raw_spin_lock(&release_list_lock);
- if (!cgroup_is_dead(cgrp) &&
- list_empty(&cgrp->release_list)) {
- list_add(&cgrp->release_list, &release_list);
- need_schedule_work = 1;
- }
- raw_spin_unlock(&release_list_lock);
- if (need_schedule_work)
- schedule_work(&release_agent_work);
+ if (!queue_work(cgroup_destroy_wq, &cgrp->self.destroy_work))
+ cgroup_put(cgrp);
}
}
@@ -5317,52 +5299,40 @@ static void check_for_release(struct cgroup *cgrp)
*/
static void cgroup_release_agent(struct work_struct *work)
{
- BUG_ON(work != &release_agent_work);
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+ struct cgroup *cgrp = css->cgroup;
+ char *pathbuf = NULL, *agentbuf = NULL, *path;
+ char *argv[3], *envp[3];
+
mutex_lock(&cgroup_mutex);
- raw_spin_lock(&release_list_lock);
- while (!list_empty(&release_list)) {
- char *argv[3], *envp[3];
- int i;
- char *pathbuf = NULL, *agentbuf = NULL, *path;
- struct cgroup *cgrp = list_entry(release_list.next,
- struct cgroup,
- release_list);
- list_del_init(&cgrp
