linux-kernel - [tip: timers/core] timers: Split out forward timer base functionality

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Message-ID: <170308794724.398.14686394808339432944.tip-bot2@tip-bot2>
Date: Wed, 20 Dec 2023 15:59:07 -0000
From: "tip-bot2 for Anna-Maria Behnsen" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Anna-Maria Behnsen" <anna-maria@...utronix.de>,
 Thomas Gleixner <tglx@...utronix.de>,
 Frederic Weisbecker <frederic@...nel.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/core] timers: Split out forward timer base functionality

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     1e490484aa3af42d4eeffabf96d6a02be69d586b
Gitweb:        https://git.kernel.org/tip/1e490484aa3af42d4eeffabf96d6a02be69d586b
Author:        Anna-Maria Behnsen <anna-maria@...utronix.de>
AuthorDate:    Fri, 01 Dec 2023 10:26:31 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Wed, 20 Dec 2023 16:49:38 +01:00

timers: Split out forward timer base functionality

Forwarding timer base is done when the next expiry value is calculated and
when a new timer is enqueued. When the next expiry value is calculated the
jiffies value is already available and does not need to be reread a second
time.

Splitting out the forward timer base functionality to make it executable
via both contextes - those where jiffies are already known and those, where
jiffies need to be read.

No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Frederic Weisbecker <frederic@...nel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-10-anna-maria@linutronix.de

---
 kernel/time/timer.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index f75f932..5b02e16 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -939,30 +939,34 @@ get_target_base(struct timer_base *base, unsigned tflags)
 	return get_timer_this_cpu_base(tflags);
 }
 
-static inline void forward_timer_base(struct timer_base *base)
+static inline void __forward_timer_base(struct timer_base *base,
+					unsigned long basej)
 {
-	unsigned long jnow = READ_ONCE(jiffies);
-
 	/*
 	 * Check whether we can forward the base. We can only do that when
 	 * @basej is past base->clk otherwise we might rewind base->clk.
 	 */
-	if (time_before_eq(jnow, base->clk))
+	if (time_before_eq(basej, base->clk))
 		return;
 
 	/*
 	 * If the next expiry value is > jiffies, then we fast forward to
 	 * jiffies otherwise we forward to the next expiry value.
 	 */
-	if (time_after(base->next_expiry, jnow)) {
-		base->clk = jnow;
+	if (time_after(base->next_expiry, basej)) {
+		base->clk = basej;
 	} else {
 		if (WARN_ON_ONCE(time_before(base->next_expiry, base->clk)))
 			return;
 		base->clk = base->next_expiry;
 	}
+
 }
 
+static inline void forward_timer_base(struct timer_base *base)
+{
+	__forward_timer_base(base, READ_ONCE(jiffies));
+}
 
 /*
  * We are using hashed locking: Holding per_cpu(timer_bases[x]).lock means