cgroup/freezer: Add cgroup CGRP_FROZEN flag update helper

Add help to update cgroup CGRP_FROZEN flag. Both cgroup_propagate_frozen
and cgroup_update_frozen functions update CGRP_FROZEN flag, this makes
code concise.

Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/freezer.c b/kernel/cgroup/freezer.c
index 188d5f2aeb5aa6f4282ef4f445f1ec5cdcf709de..bf1690a167dda0ae474e2417d99d2a5f5b93dca7 100644 (file)
--- a/kernel/cgroup/freezer.c
+++ b/kernel/cgroup/freezer.c
@@ -8,6 +8,28 @@
 
 #include <trace/events/cgroup.h>
 
+/*
+ * Update CGRP_FROZEN of cgroup.flag
+ * Return true if flags is updated; false if flags has no change
+ */
+static bool cgroup_update_frozen_flag(struct cgroup *cgrp, bool frozen)
+{
+       lockdep_assert_held(&css_set_lock);
+
+       /* Already there? */
+       if (test_bit(CGRP_FROZEN, &cgrp->flags) == frozen)
+               return false;
+
+       if (frozen)
+               set_bit(CGRP_FROZEN, &cgrp->flags);
+       else
+               clear_bit(CGRP_FROZEN, &cgrp->flags);
+
+       cgroup_file_notify(&cgrp->events_file);
+       TRACE_CGROUP_PATH(notify_frozen, cgrp, frozen);
+       return true;
+}
+
 /*
  * Propagate the cgroup frozen state upwards by the cgroup tree.
  */
@@ -24,24 +46,16 @@ static void cgroup_propagate_frozen(struct cgroup *cgrp, bool frozen)
        while ((cgrp = cgroup_parent(cgrp))) {
                if (frozen) {
                        cgrp->freezer.nr_frozen_descendants += desc;
-                       if (!test_bit(CGRP_FROZEN, &cgrp->flags) &&
-                           test_bit(CGRP_FREEZE, &cgrp->flags) &&
-                           cgrp->freezer.nr_frozen_descendants ==
-                           cgrp->nr_descendants) {
-                               set_bit(CGRP_FROZEN, &cgrp->flags);
-                               cgroup_file_notify(&cgrp->events_file);
-                               TRACE_CGROUP_PATH(notify_frozen, cgrp, 1);
-                               desc++;
-                       }
+                       if (!test_bit(CGRP_FREEZE, &cgrp->flags) ||
+                           (cgrp->freezer.nr_frozen_descendants !=
+                           cgrp->nr_descendants))
+                               continue;
                } else {
                        cgrp->freezer.nr_frozen_descendants -= desc;
-                       if (test_bit(CGRP_FROZEN, &cgrp->flags)) {
-                               clear_bit(CGRP_FROZEN, &cgrp->flags);
-                               cgroup_file_notify(&cgrp->events_file);
-                               TRACE_CGROUP_PATH(notify_frozen, cgrp, 0);
-                               desc++;
-                       }
                }
+
+               if (cgroup_update_frozen_flag(cgrp, frozen))
+                       desc++;
        }
 }
 
@@ -53,8 +67,6 @@ void cgroup_update_frozen(struct cgroup *cgrp)
 {
        bool frozen;
 
-       lockdep_assert_held(&css_set_lock);
-
        /*
         * If the cgroup has to be frozen (CGRP_FREEZE bit set),
         * and all tasks are frozen and/or stopped, let's consider
@@ -63,24 +75,9 @@ void cgroup_update_frozen(struct cgroup *cgrp)
        frozen = test_bit(CGRP_FREEZE, &cgrp->flags) &&
                cgrp->freezer.nr_frozen_tasks == __cgroup_task_count(cgrp);
 
-       if (frozen) {
-               /* Already there? */
-               if (test_bit(CGRP_FROZEN, &cgrp->flags))
-                       return;
-
-               set_bit(CGRP_FROZEN, &cgrp->flags);
-       } else {
-               /* Already there? */
-               if (!test_bit(CGRP_FROZEN, &cgrp->flags))
-                       return;
-
-               clear_bit(CGRP_FROZEN, &cgrp->flags);
-       }
-       cgroup_file_notify(&cgrp->events_file);
-       TRACE_CGROUP_PATH(notify_frozen, cgrp, frozen);
-
-       /* Update the state of ancestor cgroups. */
-       cgroup_propagate_frozen(cgrp, frozen);
+       /* If flags is updated, update the state of ancestor cgroups. */
+       if (cgroup_update_frozen_flag(cgrp, frozen))
+               cgroup_propagate_frozen(cgrp, frozen);
 }
 
 /*