hrtimer: Ensure timerfd notification for HIGHRES=n

If high resolution timers are disabled the timerfd notification about a
clock was set event is not happening for all cases which use
clock_was_set_delayed() because that's a NOP for HIGHRES=n, which is wrong.

Make clock_was_set_delayed() unconditially available to fix that.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.196661266@linutronix.de

include/linux/hrtimer.h

@@ -318,16 +318,12 @@ struct clock_event_device;
 
 extern void hrtimer_interrupt(struct clock_event_device *dev);
 
-extern void clock_was_set_delayed(void);
-
 extern unsigned int hrtimer_resolution;
 
 #else
 
 #define hrtimer_resolution	(unsigned int)LOW_RES_NSEC
 
-static inline void clock_was_set_delayed(void) { }
-
 #endif
 
 static inline ktime_t
@@ -351,7 +347,6 @@ hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
 						    timer->base->get_time());
 }
 
-extern void clock_was_set(void);
 #ifdef CONFIG_TIMERFD
 extern void timerfd_clock_was_set(void);
 #else

kernel/time/hrtimer.c

@@ -777,22 +777,6 @@ static void hrtimer_switch_to_hres(void)
 	retrigger_next_event(NULL);
 }
 
-static void clock_was_set_work(struct work_struct *work)
-{
-	clock_was_set();
-}
-
-static DECLARE_WORK(hrtimer_work, clock_was_set_work);
-
-/*
- * Called from timekeeping and resume code to reprogram the hrtimer
- * interrupt device on all cpus.
- */
-void clock_was_set_delayed(void)
-{
-	schedule_work(&hrtimer_work);
-}
-
 #else
 
 static inline int hrtimer_is_hres_enabled(void) { return 0; }
@@ -877,6 +861,22 @@ void clock_was_set(void)
 	timerfd_clock_was_set();
 }
 
+static void clock_was_set_work(struct work_struct *work)
+{
+	clock_was_set();
+}
+
+static DECLARE_WORK(hrtimer_work, clock_was_set_work);
+
+/*
+ * Called from timekeeping and resume code to reprogram the hrtimer
+ * interrupt device on all cpus and to notify timerfd.
+ */
+void clock_was_set_delayed(void)
+{
+	schedule_work(&hrtimer_work);
+}
+
 /*
  * During resume we might have to reprogram the high resolution timer
  * interrupt on all online CPUs.  However, all other CPUs will be

kernel/time/tick-internal.h

@@ -165,3 +165,6 @@ DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases);
 
 extern u64 get_next_timer_interrupt(unsigned long basej, u64 basem);
 void timer_clear_idle(void);
+
+void clock_was_set(void);
+void clock_was_set_delayed(void);