[tip:timers/core] hrtimer: Make the hrtimer_cpu_base::hres_active field unconditional, to simplify the code

[tip-bot for Anna-Maria Gleixner]

Commit-ID:  28bfd18bf3daa5db8bb3422ea7138c8b7d2444ac
Gitweb:     https://git.kernel.org/tip/28bfd18bf3daa5db8bb3422ea7138c8b7d2444ac
Author:     Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
AuthorDate: Thu, 21 Dec 2017 11:41:42 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 16 Jan 2018 02:35:47 +0100

hrtimer: Make the hrtimer_cpu_base::hres_active field unconditional, to simplify the code

The hrtimer_cpu_base::hres_active_member field depends on CONFIG_HIGH_RES_TIMERS=y
currently, and all related functions to this member are conditional as well.

To simplify the code make it unconditional and set it to zero during initialization.

(This will also help with the upcoming softirq based hrtimers code.)

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

There is no functional change.

Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: keescook@xxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20171221104205.7269-14-anna-maria@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/linux/hrtimer.h | 20 ++++++++------------
 kernel/time/hrtimer.c   | 31 +++++++++++++++----------------
 2 files changed, 23 insertions(+), 28 deletions(-)

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 56e56bc..22627b3 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -161,8 +161,8 @@ enum  hrtimer_base_type {
  * @cpu:		cpu number
  * @active_bases:	Bitfield to mark bases with active timers
  * @clock_was_set_seq:	Sequence counter of clock was set events
- * @in_hrtirq:		hrtimer_interrupt() is currently executing
  * @hres_active:	State of high resolution mode
+ * @in_hrtirq:		hrtimer_interrupt() is currently executing
  * @hang_detected:	The last hrtimer interrupt detected a hang
  * @expires_next:	absolute time of the next event, is required for remote
  *			hrtimer enqueue
@@ -182,9 +182,9 @@ struct hrtimer_cpu_base {
 	unsigned int			cpu;
 	unsigned int			active_bases;
 	unsigned int			clock_was_set_seq;
+	unsigned int			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;
@@ -266,16 +266,17 @@ static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 	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
@@ -298,11 +299,6 @@ 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
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index e56805f..b688090 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -512,6 +512,20 @@ static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
 					    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
 
@@ -541,19 +555,6 @@ static inline int hrtimer_is_hres_enabled(void)
 }
 
 /*
- * 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
@@ -661,7 +662,6 @@ static void hrtimer_reprogram(struct hrtimer *timer,
 static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
 {
 	base->expires_next = KTIME_MAX;
-	base->hres_active = 0;
 }
 
 /*
@@ -720,8 +720,6 @@ 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
@@ -1600,6 +1598,7 @@ int hrtimers_prepare_cpu(unsigned int cpu)
 	}
 
 	cpu_base->cpu = cpu;
+	cpu_base->hres_active = 0;
 	hrtimer_init_hres(cpu_base);
 	return 0;
 }