clockevents: Make suspend/resume calls explicit

clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call.

We are way better off to have explicit calls instead of this
monstrosity. Split out the suspend/resume() calls and invoke
them directly from the call sites.

No locking required at this point because these calls happen
with interrupts disabled and a single cpu online.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebased on top of 4.0-rc5. ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/713674030.jVm1qaHuPf@vostro.rjw.lan
[ Rebased on top of latest timers/core. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/xen/suspend.c

 #include <linux/types.h>
-#include <linux/clockchips.h>
+#include <linux/tick.h>
 
 #include <xen/interface/xen.h>
 #include <xen/grant_table.h>
@@ -81,17 +81,14 @@ void xen_arch_post_suspend(int cancelled)
 
 static void xen_vcpu_notify_restore(void *data)
 {
-	unsigned long reason = (unsigned long)data;
-
 	/* Boot processor notified via generic timekeeping_resume() */
-	if ( smp_processor_id() == 0)
+	if (smp_processor_id() == 0)
 		return;
 
-	clockevents_notify(reason, NULL);
+	tick_resume();
 }
 
 void xen_arch_resume(void)
 {
-	on_each_cpu(xen_vcpu_notify_restore,
-		    (void *)CLOCK_EVT_NOTIFY_RESUME, 1);
+	on_each_cpu(xen_vcpu_notify_restore, NULL, 1);
 }

include/linux/clockchips.h

@@ -16,8 +16,6 @@ enum clock_event_nofitiers {
 	CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
 	CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
 	CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
-	CLOCK_EVT_NOTIFY_SUSPEND,
-	CLOCK_EVT_NOTIFY_RESUME,
 	CLOCK_EVT_NOTIFY_CPU_DYING,
 	CLOCK_EVT_NOTIFY_CPU_DEAD,
 };

include/linux/tick.h

@@ -29,10 +29,13 @@ extern struct tick_device *tick_get_device(int cpu);
 extern void __init tick_init(void);
 extern void tick_freeze(void);
 extern void tick_unfreeze(void);
+/* Should be core only, but XEN resume magic abuses this interface */
+extern void tick_resume(void);
 #else /* CONFIG_GENERIC_CLOCKEVENTS */
 static inline void tick_init(void) { }
 static inline void tick_freeze(void) { }
 static inline void tick_unfreeze(void) { }
+static inline void tick_resume(void) { }
 #endif /* !CONFIG_GENERIC_CLOCKEVENTS */
 
 #ifdef CONFIG_TICK_ONESHOT

kernel/time/clockevents.c

@@ -670,15 +670,6 @@ int clockevents_notify(unsigned long reason, void *arg)
 		tick_handover_do_timer(arg);
 		break;
 
-	case CLOCK_EVT_NOTIFY_SUSPEND:
-		tick_suspend();
-		tick_suspend_broadcast();
-		break;
-
-	case CLOCK_EVT_NOTIFY_RESUME:
-		tick_resume();
-		break;
-
 	case CLOCK_EVT_NOTIFY_CPU_DEAD:
 		tick_shutdown_broadcast_oneshot(arg);
 		tick_shutdown_broadcast(arg);

kernel/time/tick-common.c

@@ -373,18 +373,39 @@ void tick_shutdown(unsigned int *cpup)
 	}
 }
 
+/**
+ * tick_suspend - Suspend the tick and the broadcast device
+ *
+ * Called from syscore_suspend() via timekeeping_suspend with only one
+ * CPU online and interrupts disabled or from tick_unfreeze() under
+ * tick_freeze_lock.
+ *
+ * No locks required. Nothing can change the per cpu device.
+ */
 void tick_suspend(void)
 {
 	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
 
 	clockevents_shutdown(td->evtdev);
+	tick_suspend_broadcast();
 }
 
+/**
+ * tick_resume - Resume the tick and the broadcast device
+ *
+ * Called from syscore_resume() via timekeeping_resume with only one
+ * CPU online and interrupts disabled or from tick_unfreeze() under
+ * tick_freeze_lock.
+ *
+ * No locks required. Nothing can change the per cpu device.
+ */
 void tick_resume(void)
 {
-	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
-	int broadcast = tick_resume_broadcast();
+	struct tick_device *td;
+	int broadcast;
 
+	broadcast = tick_resume_broadcast();
+	td = this_cpu_ptr(&tick_cpu_device);
 	clockevents_tick_resume(td->evtdev);
 
 	if (!broadcast) {
@@ -416,7 +437,6 @@ void tick_freeze(void)
 		timekeeping_suspend();
 	} else {
 		tick_suspend();
-		tick_suspend_broadcast();
 	}
 
 	raw_spin_unlock(&tick_freeze_lock);

kernel/time/tick-internal.h

@@ -23,7 +23,6 @@ extern void tick_check_new_device(struct clock_event_device *dev);
 extern void tick_handover_do_timer(int *cpup);
 extern void tick_shutdown(unsigned int *cpup);
 extern void tick_suspend(void);
-extern void tick_resume(void);
 extern bool tick_check_replacement(struct clock_event_device *curdev,
 				   struct clock_event_device *newdev);
 extern void tick_install_replacement(struct clock_event_device *dev);
@@ -42,6 +41,8 @@ extern void clockevents_exchange_device(struct clock_event_device *old,
 extern void clockevents_handle_noop(struct clock_event_device *dev);
 extern int __clockevents_update_freq(struct clock_event_device *dev, u32 freq);
 extern ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt);
+#else
+static inline void tick_suspend(void) { }
 #endif /* GENERIC_CLOCKEVENTS */
 
 /* Oneshot related functions */

kernel/time/timekeeping.c

@@ -1389,9 +1389,7 @@ void timekeeping_resume(void)
 
 	touch_softlockup_watchdog();
 
-	clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
-
-	/* Resume hrtimers */
+	tick_resume();
 	hrtimers_resume();
 }
 
@@ -1444,7 +1442,7 @@ int timekeeping_suspend(void)
 	write_seqcount_end(&tk_core.seq);
 	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 
-	clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
+	tick_suspend();
 	clocksource_suspend();
 	clockevents_suspend();