sched/deadline: Fix missing clock update

A missing clock update is causing the following warning:

rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 10 PID: 0 at kernel/sched/sched.h:963 inactive_task_timer+0x5d6/0x720
Call Trace:
<IRQ>
__hrtimer_run_queues+0x10f/0x530
hrtimer_interrupt+0xe5/0x240
smp_apic_timer_interrupt+0x79/0x2b0
apic_timer_interrupt+0xf/0x20
</IRQ>
do_idle+0x203/0x280
cpu_startup_entry+0x6f/0x80
start_secondary+0x1b0/0x200
secondary_startup_64+0xa5/0xb0
hardirqs last enabled at (793919): [<ffffffffa27c5f6e>] cpuidle_enter_state+0x9e/0x360
hardirqs last disabled at (793920): [<ffffffffa2a0096e>] interrupt_entry+0xce/0xe0
softirqs last enabled at (793922): [<ffffffffa20bef78>] irq_enter+0x68/0x70
softirqs last disabled at (793921): [<ffffffffa20bef5d>] irq_enter+0x4d/0x70

This happens because inactive_task_timer() calls sub_running_bw() (if
TASK_DEAD and non_contending) that might trigger a schedutil update,
which might access the clock. Clock is however currently updated only
later in inactive_task_timer() function.

Fix the problem by updating the clock right after task_rq_lock().

Reported-by: kernel test robot <[e-mail]>
Signed-off-by: Juri Lelli <[e-mail]>
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Cc: Claudio Scordino <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Luca Abeni <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

kernel/sched/deadline.c

···
 
 	rq = task_rq_lock(p, &rf);
 
+	sched_clock_tick();
+	update_rq_clock(rq);
+
 	if (!dl_task(p) || p->state == TASK_DEAD) {
 		struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
 
···
 	}
 	if (dl_se->dl_non_contending == 0)
 		goto unlock;
-
-	sched_clock_tick();
-	update_rq_clock(rq);
 
 	sub_running_bw(dl_se, &rq->dl);
 	dl_se->dl_non_contending = 0;