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

Anna-Maria Gleixner
2017-10-22T21:49:15Z

[-- Attachment #1: hrtimer--make-hrtimer_hres_active---available-in-all-cases.patch --]
[-- Type: text/plain, Size: 3889 bytes --]

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@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
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;
}