cgroup/cpuset: add callback_lock helper

To modify cpuset, both cpuset_mutex and callback_lock are needed. Add
helpers for cpuset-v1 to get callback_lock.

Signed-off-by: Chen Ridong <[email protected]>
Acked-by: Waiman Long <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

Author: Chen Ridong

kernel/cgroup/cpuset-internal.h

@@ -239,6 +239,8 @@ static inline int is_spread_slab(const struct cpuset *cs)
 }
 
 void rebuild_sched_domains_locked(void);
+void callback_lock_irq(void);
+void callback_unlock_irq(void);
 
 /*
  * cpuset-v1.c

kernel/cgroup/cpuset.c

@@ -275,6 +275,16 @@ void cpuset_unlock(void)
 
 static DEFINE_SPINLOCK(callback_lock);
 
+void callback_lock_irq(void)
+{
+	spin_lock_irq(&callback_lock);
+}
+
+void callback_unlock_irq(void)
+{
+	spin_unlock_irq(&callback_lock);
+}
+
 static struct workqueue_struct *cpuset_migrate_mm_wq;
 
 static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);