Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

[sfrench/cifs-2.6.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c03a640ef6da265db01b93c2970ab6b2da7abd67..d27904c193daa1d8a8680522093254cfde376177 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -58,6 +58,7 @@
 #include <linux/kthread.h>
 #include <linux/delay.h>
 #include <linux/atomic.h>
+#include <linux/cpuset.h>
 #include <net/sock.h>
 
 /*
@@ -2739,6 +2740,7 @@ out_unlock_rcu:
 out_unlock_threadgroup:
        percpu_up_write(&cgroup_threadgroup_rwsem);
        cgroup_kn_unlock(of->kn);
+       cpuset_post_attach_flush();
        return ret ?: nbytes;
 }
 
@@ -4655,14 +4657,15 @@ static void css_free_work_fn(struct work_struct *work)
 
        if (ss) {
                /* css free path */
+               struct cgroup_subsys_state *parent = css->parent;
                int id = css->id;
 
-               if (css->parent)
-                       css_put(css->parent);
-
                ss->css_free(css);
                cgroup_idr_remove(&ss->css_idr, id);
                cgroup_put(cgrp);
+
+               if (parent)
+                       css_put(parent);
        } else {
                /* cgroup free path */
                atomic_dec(&cgrp->root->nr_cgrps);
@@ -4758,6 +4761,7 @@ static void init_and_link_css(struct cgroup_subsys_state *css,
        INIT_LIST_HEAD(&css->sibling);
        INIT_LIST_HEAD(&css->children);
        css->serial_nr = css_serial_nr_next++;
+       atomic_set(&css->online_cnt, 0);
 
        if (cgroup_parent(cgrp)) {
                css->parent = cgroup_css(cgroup_parent(cgrp), ss);
@@ -4780,6 +4784,10 @@ static int online_css(struct cgroup_subsys_state *css)
        if (!ret) {
                css->flags |= CSS_ONLINE;
                rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
+
+               atomic_inc(&css->online_cnt);
+               if (css->parent)
+                       atomic_inc(&css->parent->online_cnt);
        }
        return ret;
 }
@@ -5017,10 +5025,15 @@ static void css_killed_work_fn(struct work_struct *work)
                container_of(work, struct cgroup_subsys_state, destroy_work);
 
        mutex_lock(&cgroup_mutex);
-       offline_css(css);
-       mutex_unlock(&cgroup_mutex);
 
-       css_put(css);
+       do {
+               offline_css(css);
+               css_put(css);
+               /* @css can't go away while we're holding cgroup_mutex */
+               css = css->parent;
+       } while (css && atomic_dec_and_test(&css->online_cnt));
+
+       mutex_unlock(&cgroup_mutex);
 }
 
 /* css kill confirmation processing requires process context, bounce */
@@ -5029,8 +5042,10 @@ static void css_killed_ref_fn(struct percpu_ref *ref)
        struct cgroup_subsys_state *css =
                container_of(ref, struct cgroup_subsys_state, refcnt);
 
-       INIT_WORK(&css->destroy_work, css_killed_work_fn);
-       queue_work(cgroup_destroy_wq, &css->destroy_work);
+       if (atomic_dec_and_test(&css->online_cnt)) {
+               INIT_WORK(&css->destroy_work, css_killed_work_fn);
+               queue_work(cgroup_destroy_wq, &css->destroy_work);
+       }
 }
 
 /**