linux-kernel - [PATCH v8 09/25] timer: Split out get next timer functionality

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Message-Id: <20231004123454.15691-10-anna-maria@linutronix.de>
Date:   Wed,  4 Oct 2023 14:34:38 +0200
From:   Anna-Maria Behnsen <anna-maria@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        John Stultz <jstultz@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Eric Dumazet <edumazet@...gle.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Arjan van de Ven <arjan@...radead.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Rik van Riel <riel@...riel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Siewior <bigeasy@...utronix.de>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        Lukasz Luba <lukasz.luba@....com>,
        "Gautham R . Shenoy" <gautham.shenoy@....com>,
        Srinivas Pandruvada <srinivas.pandruvada@...el.com>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Anna-Maria Behnsen <anna-maria@...utronix.de>
Subject: [PATCH v8 09/25] timer: Split out get next timer functionality

Split out get next timer functionality to make it reusable in other
places. Thereby the order of getting the next expiry, forwarding the base
clock and mark timer bases as idle, is changed. This change of order
shouldn't have any impact, as nothing inside the function relies on the
idle value or the updated timer base clock.

Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
---
 kernel/time/timer.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 18f8aac9b19a..f443aa807fbc 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1911,6 +1911,24 @@ static u64 cmp_next_hrtimer_event(u64 basem, u64 expires)
 	return DIV_ROUND_UP_ULL(nextevt, TICK_NSEC) * TICK_NSEC;
 }
 
+static inline unsigned long __get_next_timer_interrupt(unsigned long basej,
+						       struct timer_base *base)
+{
+	unsigned long nextevt;
+
+	if (base->next_expiry_recalc)
+		next_expiry_recalc(base);
+	nextevt = base->next_expiry;
+
+	if (base->timers_pending) {
+		/* If we missed a tick already, force 0 delta */
+		if (time_before(nextevt, basej))
+			nextevt = basej;
+	}
+
+	return nextevt;
+}
+
 /**
  * get_next_timer_interrupt - return the time (clock mono) of the next timer
  * @basej:	base time jiffies
@@ -1933,9 +1951,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
 		return expires;
 
 	raw_spin_lock(&base->lock);
-	if (base->next_expiry_recalc)
-		next_expiry_recalc(base);
-	nextevt = base->next_expiry;
+	nextevt = __get_next_timer_interrupt(basej, base);
 
 	/*
 	 * We have a fresh next event. Check whether we can forward the
@@ -1952,14 +1968,10 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
 	 */
 	base->is_idle = time_after(nextevt, basej + 1);
 
-	if (base->timers_pending) {
-		/* If we missed a tick already, force 0 delta */
-		if (time_before(nextevt, basej))
-			nextevt = basej;
-		expires = basem + (u64)(nextevt - basej) * TICK_NSEC;
-	}
 	raw_spin_unlock(&base->lock);
 
+	expires = basem + (u64)(nextevt - basej) * TICK_NSEC;
+
 	return cmp_next_hrtimer_event(basem, expires);
 }
 
-- 
2.39.2