[PATCH v2 13/37] hrtimer: Reduce conditional code (hres_active)

[Anna-Maria Gleixner]

The hrtimer_cpu_base struct has the CONFIG_HIGH_RES_TIMERS conditional
struct member hres_active. All related functions to this member are
conditional as well.

There is no functional change, when the hres_active member is
unconditional with all related functions and is set to zero during
initialization.

The conditional code sections can be avoided by adding IS_ENABLED(HIGHRES)
conditionals into common functions, which ensures dead code elimination.

Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
---
 include/linux/hrtimer.h |   20 ++++++++------------
 kernel/time/hrtimer.c   |   31 +++++++++++++++----------------
 2 files changed, 23 insertions(+), 28 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -185,10 +185,10 @@ struct hrtimer_cpu_base {
 	unsigned int			active_bases;
 	unsigned int			clock_was_set_seq;
 	unsigned int			migration_enabled	: 1,
-					nohz_active		: 1;
+					nohz_active		: 1,
+					hres_active		: 1;
 #ifdef CONFIG_HIGH_RES_TIMERS
 	unsigned int			in_hrtirq	: 1,
-					hres_active	: 1,
 					hang_detected	: 1;
 	ktime_t				expires_next;
 	struct hrtimer			*next_timer;
@@ -270,16 +270,17 @@ static inline ktime_t hrtimer_cb_get_tim
 	return timer->base->get_time();
 }
 
+static inline int hrtimer_is_hres_active(struct hrtimer *timer)
+{
+	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
+		timer->base->cpu_base->hres_active : 0;
+}
+
 #ifdef CONFIG_HIGH_RES_TIMERS
 struct clock_event_device;
 
 extern void hrtimer_interrupt(struct clock_event_device *dev);
 
-static inline int hrtimer_is_hres_active(struct hrtimer *timer)
-{
-	return timer->base->cpu_base->hres_active;
-}
-
 /*
  * The resolution of the clocks. The resolution value is returned in
  * the clock_getres() system call to give application programmers an
@@ -302,11 +303,6 @@ extern unsigned int hrtimer_resolution;
 
 #define hrtimer_resolution	(unsigned int)LOW_RES_NSEC
 
-static inline int hrtimer_is_hres_active(struct hrtimer *timer)
-{
-	return 0;
-}
-
 static inline void clock_was_set_delayed(void) { }
 
 #endif
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -519,6 +519,20 @@ static inline ktime_t hrtimer_update_bas
 					    offs_real, offs_boot, offs_tai);
 }
 
+/*
+ * Is the high resolution mode active ?
+ */
+static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
+{
+	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
+		cpu_base->hres_active : 0;
+}
+
+static inline int hrtimer_hres_active(void)
+{
+	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
+}
+
 /* High resolution timer related functions */
 #ifdef CONFIG_HIGH_RES_TIMERS
 
@@ -548,19 +562,6 @@ static inline int hrtimer_is_hres_enable
 }
 
 /*
- * Is the high resolution mode active ?
- */
-static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
-{
-	return cpu_base->hres_active;
-}
-
-static inline int hrtimer_hres_active(void)
-{
-	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
-}
-
-/*
  * Reprogram the event source with checking both queues for the
  * next event
  * Called with interrupts disabled and base->lock held
@@ -668,7 +669,6 @@ static void hrtimer_reprogram(struct hrt
 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
 {
 	base->expires_next = KTIME_MAX;
-	base->hres_active = 0;
 }
 
 /*
@@ -727,8 +727,6 @@ void clock_was_set_delayed(void)
 
 #else
 
-static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *b) { return 0; }
-static inline int hrtimer_hres_active(void) { return 0; }
 static inline int hrtimer_is_hres_enabled(void) { return 0; }
 static inline void hrtimer_switch_to_hres(void) { }
 static inline void
@@ -1609,6 +1607,7 @@ int hrtimers_prepare_cpu(unsigned int cp
 	}
 
 	cpu_base->cpu = cpu;
+	cpu_base->hres_active = 0;
 	hrtimer_init_hres(cpu_base);
 	return 0;
 }