Commit 298dbd1c authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

tick: broadcast: Simplify oneshot logic and shorten lock region 



Simplify the oneshot logic by avoiding the reprogramming loops. That
also allows to call the cpu local handler outside of the
broadcast_lock held region.

Tested-by: default avatarBorislav Petkov <bp@alien8.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 2951d5c0

kernel/time/tick-broadcast.c

+17 −25
Original line number Diff line number Diff line
@@ -525,18 +525,14 @@ static void tick_broadcast_set_affinity(struct clock_event_device *bc, 
	irq_set_affinity(bc->irq, bc->cpumask);

}



static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu,

				    ktime_t expires, int force)

static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,

				     ktime_t expires)

{

	int ret;



	if (bc->state != CLOCK_EVT_STATE_ONESHOT)

		clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);



	ret = clockevents_program_event(bc, expires, force);

	if (!ret)

	clockevents_program_event(bc, expires, 1);

	tick_broadcast_set_affinity(bc, cpumask_of(cpu));

	return ret;

}



static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
@@ -573,9 +569,9 @@ static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) 
	struct tick_device *td;

	ktime_t now, next_event;

	int cpu, next_cpu = 0;

	bool bc_local;



	raw_spin_lock(&tick_broadcast_lock);

again:

	dev->next_event.tv64 = KTIME_MAX;

	next_event.tv64 = KTIME_MAX;

	cpumask_clear(tmpmask);
@@ -615,13 +611,9 @@ static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) 
		cpumask_and(tmpmask, tmpmask, cpu_online_mask);



	/*

	 * Wakeup the cpus which have an expired event and handle the

	 * broadcast event of the local cpu.

	 * Wakeup the cpus which have an expired event.

	 */

	if (tick_do_broadcast(tmpmask)) {

		td = this_cpu_ptr(&tick_cpu_device);

		td->evtdev->event_handler(td->evtdev);

	}

	bc_local = tick_do_broadcast(tmpmask);



	/*

	 * Two reasons for reprogram:
@@ -633,15 +625,15 @@ static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) 
	 * - There are pending events on sleeping CPUs which were not

	 * in the event mask

	 */

	if (next_event.tv64 != KTIME_MAX) {

		/*

		 * Rearm the broadcast device. If event expired,

		 * repeat the above

		 */

		if (tick_broadcast_set_event(dev, next_cpu, next_event, 0))

			goto again;

	}

	if (next_event.tv64 != KTIME_MAX)

		tick_broadcast_set_event(dev, next_cpu, next_event);



	raw_spin_unlock(&tick_broadcast_lock);



	if (bc_local) {

		td = this_cpu_ptr(&tick_cpu_device);

		td->evtdev->event_handler(td->evtdev);

	}

}



static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
@@ -723,7 +715,7 @@ int tick_broadcast_oneshot_control(enum tick_broadcast_state state) 
			 */

			if (!cpumask_test_cpu(cpu, tick_broadcast_force_mask) &&

			    dev->next_event.tv64 < bc->next_event.tv64)

				tick_broadcast_set_event(bc, cpu, dev->next_event, 1);

				tick_broadcast_set_event(bc, cpu, dev->next_event);

		}

		/*

		 * If the current CPU owns the hrtimer broadcast
@@ -858,7 +850,7 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) 
			clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);

			tick_broadcast_init_next_event(tmpmask,

						       tick_next_period);

			tick_broadcast_set_event(bc, cpu, tick_next_period, 1);

			tick_broadcast_set_event(bc, cpu, tick_next_period);

		} else

			bc->next_event.tv64 = KTIME_MAX;

	} else {