patches/0008-hrtimer-Reduce-conditional-code-expires_next-next_ti.patch

From: Anna-Maria Gleixner <anna-maria@linutronix.de>
Date: Thu, 31 Aug 2017 11:03:05 +0000
Subject: [PATCH 08/25] hrtimer: Reduce conditional code (expires_next,
 next_timer)

The hrtimer_cpu_base struct member expires_next and next_timer are
conditional members (CONFIG_HIGH_RES_TIMERS). This makes the hrtimer code
more complex and harder to understand than it actually is.

Reduce the conditionals related to those two struct members.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 include/linux/hrtimer.h |   10 +++++-----
 kernel/time/hrtimer.c   |   24 +++++-------------------
 2 files changed, 10 insertions(+), 24 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -160,13 +160,13 @@ enum  hrtimer_base_type {
  * @in_hrtirq:		hrtimer_interrupt() is currently executing
  * @hres_active:	State of high resolution mode
  * @hang_detected:	The last hrtimer interrupt detected a hang
- * @expires_next:	absolute time of the next event, is required for remote
- *			hrtimer enqueue
- * @next_timer:		Pointer to the first expiring timer
  * @nr_events:		Total number of hrtimer interrupt events
  * @nr_retries:		Total number of hrtimer interrupt retries
  * @nr_hangs:		Total number of hrtimer interrupt hangs
  * @max_hang_time:	Maximum time spent in hrtimer_interrupt
+ * @expires_next:	absolute time of the next event, is required for remote
+ *			hrtimer enqueue
+ * @next_timer:		Pointer to the first expiring timer
  * @clock_base:		array of clock bases for this cpu
  *
  * Note: next_timer is just an optimization for __remove_hrtimer().
@@ -184,13 +184,13 @@ struct hrtimer_cpu_base {
 #ifdef CONFIG_HIGH_RES_TIMERS
 	unsigned int			in_hrtirq	: 1,
 					hang_detected	: 1;
-	ktime_t				expires_next;
-	struct hrtimer			*next_timer;
 	unsigned int			nr_events;
 	unsigned int			nr_retries;
 	unsigned int			nr_hangs;
 	unsigned int			max_hang_time;
 #endif
+	ktime_t				expires_next;
+	struct hrtimer			*next_timer;
 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
 } ____cacheline_aligned;
 
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -153,16 +153,16 @@ struct hrtimer_clock_base *lock_hrtimer_
 }
 
 /*
- * With HIGHRES=y we do not migrate the timer when it is expiring
- * before the next event on the target cpu because we cannot reprogram
- * the target cpu hardware and we would cause it to fire late.
+ * With high resolution timers enabled we do not migrate the timer
+ * when it is expiring before the next event on the target cpu because
+ * we cannot reprogram the target cpu hardware and we would cause it
+ * to fire late.
  *
  * Called with cpu_base->lock of target cpu held.
  */
 static int
 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
 {
-#ifdef CONFIG_HIGH_RES_TIMERS
 	ktime_t expires;
 
 	if (!new_base->cpu_base->hres_active)
@@ -170,9 +170,6 @@ hrtimer_check_target(struct hrtimer *tim
 
 	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
 	return expires <= new_base->cpu_base->expires_next;
-#else
-	return 0;
-#endif
 }
 
 #ifdef CONFIG_NO_HZ_COMMON
@@ -455,9 +452,7 @@ static inline void debug_deactivate(stru
 static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
 					     struct hrtimer *timer)
 {
-#ifdef CONFIG_HIGH_RES_TIMERS
 	cpu_base->next_timer = timer;
-#endif
 }
 
 static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
@@ -648,14 +643,6 @@ static void hrtimer_reprogram(struct hrt
 }
 
 /*
- * Initialize the high resolution related parts of cpu_base
- */
-static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
-{
-	base->expires_next = KTIME_MAX;
-}
-
-/*
  * Retrigger next event is called after clock was set
  *
  * Called with interrupts disabled via on_each_cpu()
@@ -720,7 +707,6 @@ static inline int hrtimer_reprogram(stru
 {
 	return 0;
 }
-static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
 static inline void retrigger_next_event(void *arg) { }
 
 #endif /* CONFIG_HIGH_RES_TIMERS */
@@ -1570,7 +1556,7 @@ int hrtimers_prepare_cpu(unsigned int cp
 
 	cpu_base->cpu = cpu;
 	cpu_base->hres_active = 0;
-	hrtimer_init_hres(cpu_base);
+	cpu_base->expires_next = KTIME_MAX;
 	return 0;
 }