[PATCH v4 16/17] smp: Create a new function to bringup nonboot cpus online

From: Qais Yousef
Date: Mon Mar 23 2020 - 09:52:04 EST


This is the last direct user of cpu_up() before we can hide it now as
internal implementation detail of the cpu subsystem.

Signed-off-by: Qais Yousef <qais.yousef@xxxxxxx>
CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CC: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CC: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
CC: Jiri Kosina <jkosina@xxxxxxx>
CC: Nicholas Piggin <npiggin@xxxxxxxxx>
CC: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Eiichi Tsukata <devel@xxxxxxxxxxxx>
CC: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
CC: Nadav Amit <namit@xxxxxxxxxx>
CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
CC: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
CC: linux-kernel@xxxxxxxxxxxxxxx
---
include/linux/cpu.h | 1 +
kernel/cpu.c | 12 ++++++++++++
kernel/smp.c | 9 +--------
3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index aebe8186cb07..3d3caecef395 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -94,6 +94,7 @@ void notify_cpu_starting(unsigned int cpu);
extern void cpu_maps_update_begin(void);
extern void cpu_maps_update_done(void);
extern int bringup_hibernate_cpu(unsigned int sleep_cpu);
+extern void smp_bringup_nonboot_cpus(unsigned int setup_max_cpus);

#else /* CONFIG_SMP */
#define cpuhp_tasks_frozen 0
diff --git a/kernel/cpu.c b/kernel/cpu.c
index bf39c5bfb6d9..7c6aa427a3a3 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1299,6 +1299,18 @@ int bringup_hibernate_cpu(unsigned int sleep_cpu)
return 0;
}

+void smp_bringup_nonboot_cpus(unsigned int setup_max_cpus)
+{
+ unsigned int cpu;
+
+ for_each_present_cpu(cpu) {
+ if (num_online_cpus() >= setup_max_cpus)
+ break;
+ if (!cpu_online(cpu))
+ cpu_up(cpu);
+ }
+}
+
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;

diff --git a/kernel/smp.c b/kernel/smp.c
index d0ada39eb4d4..9e793cfd6128 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -589,20 +589,13 @@ void __init setup_nr_cpu_ids(void)
void __init smp_init(void)
{
int num_nodes, num_cpus;
- unsigned int cpu;

idle_threads_init();
cpuhp_threads_init();

pr_info("Bringing up secondary CPUs ...\n");

- /* FIXME: This should be done in userspace --RR */
- for_each_present_cpu(cpu) {
- if (num_online_cpus() >= setup_max_cpus)
- break;
- if (!cpu_online(cpu))
- cpu_up(cpu);
- }
+ smp_bringup_nonboot_cpus(setup_max_cpus);

num_nodes = num_online_nodes();
num_cpus = num_online_cpus();
--
2.17.1