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Subject[PATCH v4 13/36] hrtimer: Reduce conditional code (hres_active)
Date
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(-)

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 56e56bcb6f0f..22627b3a33fe 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 80e7c15af877..ccfe340511a0 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;
}
--
2.11.0
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