cgroup: move check_for_release() invocation

To trigger release agent when the last task leaves the cgroup,
check_for_release() is called from put_css_set_locked(); however,
css_set being unlinked is being decoupled from task leaving the cgroup
and the correct condition to test is cgroup->nr_populated dropping to
zero which check_for_release() is already updated to test.

This patch moves check_for_release() invocation from
put_css_set_locked() to cgroup_update_populated().

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 435aa686567b235d268267a182aa729acb87cf6f..855313d01e85806f3c685e4dbd4feef8a857169f 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -623,6 +623,7 @@ static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
                if (!trigger)
                        break;
 
+               check_for_release(cgrp);
                cgroup_file_notify(&cgrp->events_file);
 
                cgrp = cgroup_parent(cgrp);
@@ -686,15 +687,8 @@ static void put_css_set_locked(struct css_set *cset)
        css_set_count--;
 
        list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
-               struct cgroup *cgrp = link->cgrp;
-
                list_del(&link->cset_link);
                list_del(&link->cgrp_link);
-
-               /* @cgrp can't go away while we're holding css_set_rwsem */
-               if (list_empty(&cgrp->cset_links))
-                       check_for_release(cgrp);
-
                kfree(link);
        }