Commit 1e490484 authored by Anna-Maria Behnsen's avatar Anna-Maria Behnsen Committed by Thomas Gleixner
Browse files

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: default avatarAnna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20231201092654.34614-10-anna-maria@linutronix.de
parent 8a2c9c7e

kernel/time/timer.c

+10 −6
Original line number Diff line number Diff line
@@ -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