Commit 90f5df66 authored by Richard Cochran (linutronix GmbH)'s avatar Richard Cochran (linutronix GmbH) Committed by Thomas Gleixner
Browse files

timers: Restructure internal locking 



Move the locking out from __run_timers() to the call sites, so the
protected section can be extended at the call site. Preparatory work for
changing the NOHZ timer placement to a pull at expiry time model.

No functional change.

Signed-off-by: default avatarRichard Cochran (linutronix GmbH) <richardcochran@gmail.com>
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/20240221090548.36600-15-anna-maria@linutronix.de
parent f73d9257

kernel/time/timer.c

+21 −10
Original line number Diff line number Diff line
@@ -2283,11 +2283,7 @@ static inline void __run_timers(struct timer_base *base) 
	struct hlist_head heads[LVL_DEPTH];

	int levels;



	if (time_before(jiffies, base->next_expiry))

		return;



	timer_base_lock_expiry(base);

	raw_spin_lock_irq(&base->lock);

	lockdep_assert_held(&base->lock);



	while (time_after_eq(jiffies, base->clk) &&

	       time_after_eq(jiffies, base->next_expiry)) {
@@ -2311,21 +2307,36 @@ static inline void __run_timers(struct timer_base *base) 
		while (levels--)

			expire_timers(base, heads + levels);

	}

}



static void __run_timer_base(struct timer_base *base)

{

	if (time_before(jiffies, base->next_expiry))

		return;



	timer_base_lock_expiry(base);

	raw_spin_lock_irq(&base->lock);

	__run_timers(base);

	raw_spin_unlock_irq(&base->lock);

	timer_base_unlock_expiry(base);

}



static void run_timer_base(int index)

{

	struct timer_base *base = this_cpu_ptr(&timer_bases[index]);



	__run_timer_base(base);

}



/*

 * This function runs timers and the timer-tq in bottom half context.

 */

static __latent_entropy void run_timer_softirq(struct softirq_action *h)

{

	struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_LOCAL]);



	__run_timers(base);

	run_timer_base(BASE_LOCAL);

	if (IS_ENABLED(CONFIG_NO_HZ_COMMON)) {

		__run_timers(this_cpu_ptr(&timer_bases[BASE_GLOBAL]));

		__run_timers(this_cpu_ptr(&timer_bases[BASE_DEF]));

		run_timer_base(BASE_GLOBAL);

		run_timer_base(BASE_DEF);

	}

}