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Subject[PATCH v3 2/2] cpu/hotplug: Initialise all cpuhp_cpu_state structs earlier
Date
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Price <steven.price@arm.com>
---
kernel/cpu.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 5601216eb51b..65903cb10a55 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -715,14 +715,6 @@ 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);
@@ -882,15 +874,27 @@ 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));
}
--
2.25.1
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