From 5588f5afb4cfc33eb377b751ba4b97184373e8d6 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 3 Nov 2016 15:50:00 +0100
Subject: [PATCH] lib/percpu_counter: Convert to hotplug state machine
Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161103145021.28528-5-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/cpuhotplug.h | 1 +
lib/percpu_counter.c | 25 ++++++++++++++-----------
2 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index c622ab349af33..04e5f99ffc708 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -33,6 +33,7 @@ enum cpuhp_state {
CPUHP_FS_BUFF_DEAD,
CPUHP_PRINTK_DEAD,
CPUHP_MM_MEMCQ_DEAD,
+ CPUHP_PERCPU_CNT_DEAD,
CPUHP_WORKQUEUE_PREP,
CPUHP_POWER_NUMA_PREPARE,
CPUHP_HRTIMERS_PREPARE,
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 72d36113ccaa8..c8cebb1370765 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -158,25 +158,21 @@ EXPORT_SYMBOL(percpu_counter_destroy);
int percpu_counter_batch __read_mostly = 32;
EXPORT_SYMBOL(percpu_counter_batch);
-static void compute_batch_value(void)
+static int compute_batch_value(unsigned int cpu)
{
int nr = num_online_cpus();
percpu_counter_batch = max(32, nr*2);
+ return 0;
}
-static int percpu_counter_hotcpu_callback(struct notifier_block *nb,
- unsigned long action, void *hcpu)
+static int percpu_counter_cpu_dead(unsigned int cpu)
{
#ifdef CONFIG_HOTPLUG_CPU
- unsigned int cpu;
struct percpu_counter *fbc;
- compute_batch_value();
- if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
- return NOTIFY_OK;
+ compute_batch_value(cpu);
- cpu = (unsigned long)hcpu;
spin_lock_irq(&percpu_counters_lock);
list_for_each_entry(fbc, &percpu_counters, list) {
s32 *pcount;
@@ -190,7 +186,7 @@ static int percpu_counter_hotcpu_callback(struct notifier_block *nb,
}
spin_unlock_irq(&percpu_counters_lock);
#endif
- return NOTIFY_OK;
+ return 0;
}
/*
@@ -222,8 +218,15 @@ EXPORT_SYMBOL(__percpu_counter_compare);
static int __init percpu_counter_startup(void)
{
- compute_batch_value();
- hotcpu_notifier(percpu_counter_hotcpu_callback, 0);
+ int ret;
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "lib/percpu_cnt:online",
+ compute_batch_value, NULL);
+ WARN_ON(ret < 0);
+ ret = cpuhp_setup_state_nocalls(CPUHP_PERCPU_CNT_DEAD,
+ "lib/percpu_cnt:dead", NULL,
+ percpu_counter_cpu_dead);
+ WARN_ON(ret < 0);
return 0;
}
module_init(percpu_counter_startup);
--
GitLab