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Subject[tip: smp/core] cpu/hotplug: Move bringup of secondary CPUs out of smp_init()
The following commit has been merged into the smp/core branch of tip:

Commit-ID: b99a26593b5190fac6b5c1f81a7f8cc128a25c98
Gitweb: https://git.kernel.org/tip/b99a26593b5190fac6b5c1f81a7f8cc128a25c98
Author: Qais Yousef <qais.yousef@arm.com>
AuthorDate: Mon, 23 Mar 2020 13:51:09
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 25 Mar 2020 12:59:37 +01:00

cpu/hotplug: Move bringup of secondary CPUs out of smp_init()

This is the last direct user of cpu_up() before it can become an internal
implementation detail of the cpu subsystem.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200323135110.30522-17-qais.yousef@arm.com

---
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 9dc1e89..8b295f7 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);
int bringup_hibernate_cpu(unsigned int sleep_cpu);
+void 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 f803678..4783d81 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1298,6 +1298,18 @@ int bringup_hibernate_cpu(unsigned int sleep_cpu)
return 0;
}

+void 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 97f1d97..786092a 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -597,20 +597,13 @@ 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);
- }
+ bringup_nonboot_cpus(setup_max_cpus);

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