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Subject[PATCH 09/25] hrtimer: Reduce conditional code (hrtimer_reprogram())
The hrtimer_reprogram() is currently required only when
CONFIG_HIGH_RES_TIMERS is set. Additional bitfields of hrtimer_cpu_base
struct are high resolution timer specific as well.

To simplify the hrtimer code, the behaviour of CONFIG_HIGH_RES_TIMERS and
!CONFIG_HIGH_RES_TIMERS should be similar. As preparation for this, the
function hrtimer_reprogram() and required hrtimer_cpu_base struct members
are moved outside the conditional area.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
include/linux/hrtimer.h | 6 +-
kernel/time/hrtimer.c | 131 +++++++++++++++++++++++-------------------------
2 files changed, 66 insertions(+), 71 deletions(-)

--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -180,10 +180,10 @@ struct hrtimer_cpu_base {
unsigned int clock_was_set_seq;
bool migration_enabled;
bool nohz_active;
- unsigned int hres_active : 1;
-#ifdef CONFIG_HIGH_RES_TIMERS
- unsigned int in_hrtirq : 1,
+ unsigned int hres_active : 1,
+ in_hrtirq : 1,
hang_detected : 1;
+#ifdef CONFIG_HIGH_RES_TIMERS
unsigned int nr_events;
unsigned int nr_retries;
unsigned int nr_hangs;
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -449,13 +449,13 @@ static inline void debug_deactivate(stru
trace_hrtimer_cancel(timer);
}

-#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
struct hrtimer *timer)
{
cpu_base->next_timer = timer;
}

+#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
{
unsigned int active = cpu_base->active_bases;
@@ -582,68 +582,6 @@ hrtimer_force_reprogram(struct hrtimer_c
}

/*
- * When a timer is enqueued and expires earlier than the already enqueued
- * timers, we have to check, whether it expires earlier than the timer for
- * which the clock event device was armed.
- *
- * Called with interrupts disabled and base->cpu_base.lock held
- */
-static void hrtimer_reprogram(struct hrtimer *timer,
- struct hrtimer_clock_base *base)
-{
- struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
- ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
-
- WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
-
- /*
- * If the timer is not on the current cpu, we cannot reprogram
- * the other cpus clock event device.
- */
- if (base->cpu_base != cpu_base)
- return;
-
- /*
- * If the hrtimer interrupt is running, then it will
- * reevaluate the clock bases and reprogram the clock event
- * device. The callbacks are always executed in hard interrupt
- * context so we don't need an extra check for a running
- * callback.
- */
- if (cpu_base->in_hrtirq)
- return;
-
- /*
- * CLOCK_REALTIME timer might be requested with an absolute
- * expiry time which is less than base->offset. Set it to 0.
- */
- if (expires < 0)
- expires = 0;
-
- if (expires >= cpu_base->expires_next)
- return;
-
- /* Update the pointer to the next expiring timer */
- hrtimer_update_next_timer(cpu_base, timer);
-
- /*
- * If a hang was detected in the last timer interrupt then we
- * do not schedule a timer which is earlier than the expiry
- * which we enforced in the hang detection. We want the system
- * to make progress.
- */
- if (cpu_base->hang_detected)
- return;
-
- /*
- * Program the timer hardware. We enforce the expiry for
- * events which are already in the past.
- */
- cpu_base->expires_next = expires;
- tick_program_event(expires, 1);
-}
-
-/*
* Retrigger next event is called after clock was set
*
* Called with interrupts disabled via on_each_cpu()
@@ -703,16 +641,73 @@ static inline int hrtimer_is_hres_enable
static inline void hrtimer_switch_to_hres(void) { }
static inline void
hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
-static inline int hrtimer_reprogram(struct hrtimer *timer,
- struct hrtimer_clock_base *base)
-{
- return 0;
-}
static inline void retrigger_next_event(void *arg) { }

#endif /* CONFIG_HIGH_RES_TIMERS */

/*
+ * When a timer is enqueued and expires earlier than the already enqueued
+ * timers, we have to check, whether it expires earlier than the timer for
+ * which the clock event device was armed.
+ *
+ * Called with interrupts disabled and base->cpu_base.lock held
+ */
+static void hrtimer_reprogram(struct hrtimer *timer,
+ struct hrtimer_clock_base *base)
+{
+ struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
+ ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+
+ WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
+
+ /*
+ * If the timer is not on the current cpu, we cannot reprogram
+ * the other cpus clock event device.
+ */
+ if (base->cpu_base != cpu_base)
+ return;
+
+ /*
+ * If the hrtimer interrupt is running, then it will
+ * reevaluate the clock bases and reprogram the clock event
+ * device. The callbacks are always executed in hard interrupt
+ * context so we don't need an extra check for a running
+ * callback.
+ */
+ if (cpu_base->in_hrtirq)
+ return;
+
+ /*
+ * CLOCK_REALTIME timer might be requested with an absolute
+ * expiry time which is less than base->offset. Set it to 0.
+ */
+ if (expires < 0)
+ expires = 0;
+
+ if (expires >= cpu_base->expires_next)
+ return;
+
+ /* Update the pointer to the next expiring timer */
+ hrtimer_update_next_timer(cpu_base, timer);
+
+ /*
+ * If a hang was detected in the last timer interrupt then we
+ * do not schedule a timer which is earlier than the expiry
+ * which we enforced in the hang detection. We want the system
+ * to make progress.
+ */
+ if (cpu_base->hang_detected)
+ return;
+
+ /*
+ * Program the timer hardware. We enforce the expiry for
+ * events which are already in the past.
+ */
+ cpu_base->expires_next = expires;
+ tick_program_event(expires, 1);
+}
+
+/*
* Clock realtime was set
*
* Change the offset of the realtime clock vs. the monotonic

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