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Commit 2c61eff5 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman Committed by Treehugger Robot
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Revert "hrtimers: Push pending hrtimers away from outgoing CPU earlier" 



This reverts commit 9a2fc41a which is
commit 5c0930ccaad5a74d74e8b18b648c5eb21ed2fe94 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ifdc5474de6e7488eb24959df1697b61b2e3e7880
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 8e0beabe

include/linux/cpuhotplug.h

+0 −1
Original line number Diff line number Diff line
@@ -145,7 +145,6 @@ enum cpuhp_state { 
	CPUHP_AP_ARM_CORESIGHT_STARTING,

	CPUHP_AP_ARM64_ISNDEP_STARTING,

	CPUHP_AP_SMPCFD_DYING,

	CPUHP_AP_HRTIMERS_DYING,

	CPUHP_AP_X86_TBOOT_DYING,

	CPUHP_AP_ARM_CACHE_B15_RAC_DYING,

	CPUHP_AP_ONLINE,

include/linux/hrtimer.h

+2 −2
Original line number Diff line number Diff line
@@ -497,9 +497,9 @@ extern void sysrq_timer_list_show(void); 


int hrtimers_prepare_cpu(unsigned int cpu);

#ifdef CONFIG_HOTPLUG_CPU

int hrtimers_cpu_dying(unsigned int cpu);

int hrtimers_dead_cpu(unsigned int cpu);

#else

#define hrtimers_cpu_dying	NULL

#define hrtimers_dead_cpu	NULL

#endif



#endif

kernel/cpu.c

+1 −7
Original line number Diff line number Diff line
@@ -1464,7 +1464,7 @@ static struct cpuhp_step cpuhp_hp_states[] = { 
	[CPUHP_HRTIMERS_PREPARE] = {

		.name			= "hrtimers:prepare",

		.startup.single		= hrtimers_prepare_cpu,

		.teardown.single	= NULL,

		.teardown.single	= hrtimers_dead_cpu,

	},

	[CPUHP_SMPCFD_PREPARE] = {

		.name			= "smpcfd:prepare",
@@ -1531,12 +1531,6 @@ static struct cpuhp_step cpuhp_hp_states[] = { 
		.startup.single		= NULL,

		.teardown.single	= smpcfd_dying_cpu,

	},

	[CPUHP_AP_HRTIMERS_DYING] = {

		.name			= "hrtimers:dying",

		.startup.single		= NULL,

		.teardown.single	= hrtimers_cpu_dying,

	},



	/* Entry state on starting. Interrupts enabled from here on. Transient

	 * state for synchronsization */

	[CPUHP_AP_ONLINE] = {

kernel/time/hrtimer.c

+21 −12
Original line number Diff line number Diff line
@@ -1922,22 +1922,29 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base, 
	}

}



int hrtimers_cpu_dying(unsigned int dying_cpu)

int hrtimers_dead_cpu(unsigned int scpu)

{

	struct hrtimer_cpu_base *old_base, *new_base;

	int i, ncpu = cpumask_first(cpu_active_mask);



	tick_cancel_sched_timer(dying_cpu);

	int i;



	old_base = this_cpu_ptr(&hrtimer_bases);

	new_base = &per_cpu(hrtimer_bases, ncpu);

	BUG_ON(cpu_online(scpu));

	tick_cancel_sched_timer(scpu);



	/*

	 * this BH disable ensures that raise_softirq_irqoff() does

	 * not wakeup ksoftirqd (and acquire the pi-lock) while

	 * holding the cpu_base lock

	 */

	local_bh_disable();

	local_irq_disable();

	old_base = &per_cpu(hrtimer_bases, scpu);

	new_base = this_cpu_ptr(&hrtimer_bases);

	/*

	 * The caller is globally serialized and nobody else

	 * takes two locks at once, deadlock is not possible.

	 */

	raw_spin_lock(&old_base->lock);

	raw_spin_lock_nested(&new_base->lock, SINGLE_DEPTH_NESTING);

	raw_spin_lock(&new_base->lock);

	raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);



	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {

		migrate_hrtimer_list(&old_base->clock_base[i],
@@ -1948,13 +1955,15 @@ int hrtimers_cpu_dying(unsigned int dying_cpu) 
	 * The migration might have changed the first expiring softirq

	 * timer on this CPU. Update it.

	 */

	__hrtimer_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);

	/* Tell the other CPU to retrigger the next event */

	smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);

	hrtimer_update_softirq_timer(new_base, false);



	raw_spin_unlock(&new_base->lock);

	raw_spin_unlock(&old_base->lock);

	raw_spin_unlock(&new_base->lock);



	/* Check, if we got expired work to do */

	__hrtimer_peek_ahead_timers();

	local_irq_enable();

	local_bh_enable();

	return 0;

}