Commit d308077e authored by Steven Price's avatar Steven Price Committed by Thomas Gleixner
Browse files

cpu/hotplug: Initialise all cpuhp_cpu_state structs earlier 



Rather than waiting until a CPU is first brought online, do the
initialisation of the cpuhp_cpu_state structure for each CPU during the
__init phase. This saves a (small) amount of non-__init memory and
avoids potential confusion about when the cpuhp_cpu_state struct is
valid.

Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSteven Price <steven.price@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220411152233.474129-3-steven.price@arm.com
parent 3927368b

kernel/cpu.c

+13 −9
Original line number Diff line number Diff line
@@ -716,14 +716,6 @@ static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, 
/*

 * The cpu hotplug threads manage the bringup and teardown of the cpus

 */

static void cpuhp_create(unsigned int cpu)

{

	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);



	init_completion(&st->done_up);

	init_completion(&st->done_down);

}



static int cpuhp_should_run(unsigned int cpu)

{

	struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
@@ -883,15 +875,27 @@ static int cpuhp_kick_ap_work(unsigned int cpu) 


static struct smp_hotplug_thread cpuhp_threads = {

	.store			= &cpuhp_state.thread,

	.create			= &cpuhp_create,

	.thread_should_run	= cpuhp_should_run,

	.thread_fn		= cpuhp_thread_fun,

	.thread_comm		= "cpuhp/%u",

	.selfparking		= true,

};



static __init void cpuhp_init_state(void)

{

	struct cpuhp_cpu_state *st;

	int cpu;



	for_each_possible_cpu(cpu) {

		st = per_cpu_ptr(&cpuhp_state, cpu);

		init_completion(&st->done_up);

		init_completion(&st->done_down);

	}

}



void __init cpuhp_threads_init(void)

{

	cpuhp_init_state();

	BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));

	kthread_unpark(this_cpu_read(cpuhp_state.thread));

}