sched/core: Use dl_bw_of() under rcu_read_lock_sched()

As per commit f10e00f4bf36 ("sched/dl: Use dl_bw_of() under
rcu_read_lock_sched()"), dl_bw_of() has to be protected by
rcu_read_lock_sched().

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1414497286-28824-1-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -4661,6 +4661,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur,
 	struct dl_bw *cur_dl_b;
 	unsigned long flags;
 
+	rcu_read_lock_sched();
 	cur_dl_b = dl_bw_of(cpumask_any(cur));
 	trial_cpus = cpumask_weight(trial);
 
@@ -4669,6 +4670,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur,
 	    cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
 		ret = 0;
 	raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
+	rcu_read_unlock_sched();
 
 	return ret;
 }
@@ -4697,11 +4699,13 @@ int task_can_attach(struct task_struct *p,
 					      cs_cpus_allowed)) {
 		unsigned int dest_cpu = cpumask_any_and(cpu_active_mask,
 							cs_cpus_allowed);
-		struct dl_bw *dl_b = dl_bw_of(dest_cpu);
+		struct dl_bw *dl_b;
 		bool overflow;
 		int cpus;
 		unsigned long flags;
 
+		rcu_read_lock_sched();
+		dl_b = dl_bw_of(dest_cpu);
 		raw_spin_lock_irqsave(&dl_b->lock, flags);
 		cpus = dl_bw_cpus(dest_cpu);
 		overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw);
@@ -4717,6 +4721,7 @@ int task_can_attach(struct task_struct *p,
 			__dl_add(dl_b, p->dl.dl_bw);
 		}
 		raw_spin_unlock_irqrestore(&dl_b->lock, flags);
+		rcu_read_unlock_sched();
 
 	}
 #endif