sched: fix delay accounting regression

Fix the delay accounting regression introduced by commit
75d4ef16a6aa84f708188bada182315f80aab6fa. rq no longer has sched_info
data associated with it. task_struct sched_info structure is used by delay
accounting to provide back statistics to user space.

also remove direct use of sched_clock() (which is not a valid thing to
do anymore) and use rq->clock instead.

Signed-off-by: Balbir Singh <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>

kernel/sched_stats.h

···
 # define schedstat_set(var, val)	do { } while (0)
 #endif
 
-#ifdef CONFIG_SCHEDSTATS
+#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
 /*
  * Called when a process is dequeued from the active array and given
  * the cpu.  We should note that with the exception of interactive
···
  */
 static void sched_info_arrive(struct task_struct *t)
 {
-	unsigned long long now = sched_clock(), delta = 0;
+	unsigned long long now = task_rq(t)->clock, delta = 0;
 
 	if (t->sched_info.last_queued)
 		delta = now - t->sched_info.last_queued;
···
 {
 	if (unlikely(sched_info_on()))
 		if (!t->sched_info.last_queued)
-			t->sched_info.last_queued = sched_clock();
+			t->sched_info.last_queued = task_rq(t)->clock;
 }
 
 /*
···
  */
 static inline void sched_info_depart(struct task_struct *t)
 {
-	unsigned long long delta = sched_clock() - t->sched_info.last_arrival;
+	unsigned long long delta = task_rq(t)->clock -
+					t->sched_info.last_arrival;
 
 	t->sched_info.cpu_time += delta;
 	rq_sched_info_depart(task_rq(t), delta);
···
 #else
 #define sched_info_queued(t)		do { } while (0)
 #define sched_info_switch(t, next)	do { } while (0)
-#endif /* CONFIG_SCHEDSTATS */
+#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */