[PATCH v3 05/17] timer: Rework idle logic

Anna-Maria Behnsen
2022-10-25T13:59:34Z

From: Thomas Gleixner <tglx@linutronix.de>

To improve readability of the code, split base->idle calculation and
expires calculation into separate parts.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
---
kernel/time/timer.c | 29 ++++++++++++++---------------
1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index f34bc75ff848..cb4194ecca60 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1727,21 +1727,20 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
base->clk = nextevt;
}

- if (time_before_eq(nextevt, basej)) {
- expires = basem;
- base->is_idle = false;
- } else {
- if (base->timers_pending)
- expires = basem + (u64)(nextevt - basej) * TICK_NSEC;
- /*
- * If we expect to sleep more than a tick, mark the base idle.
- * Also the tick is stopped so any added timer must forward
- * the base clk itself to keep granularity small. This idle
- * logic is only maintained for the BASE_STD base, deferrable
- * timers may still see large granularity skew (by design).
- */
- if ((expires - basem) > TICK_NSEC)
- base->is_idle = true;
+ /*
+ * Base is idle if the next event is more than a tick away. Also
+ * the tick is stopped so any added timer must forward the base clk
+ * itself to keep granularity small. This idle logic is only
+ * maintained for the BASE_STD base, deferrable timers may still
+ * see large granularity skew (by design).
+ */
+ base->is_idle = time_after(nextevt, basej + 1);
+
+ if (base->timers_pending) {
+ /* If we missed a tick already, force 0 delta */
+ if (time_before_eq(nextevt, basej))
+ nextevt = basej;
+ expires = basem + (u64)(nextevt - basej) * TICK_NSEC;
}
raw_spin_unlock(&base->lock);

--
2.30.2