1/*
2 * CPU notifier helper code for blk-mq
3 *
4 * Copyright (C) 2013-2014 Jens Axboe
5 */
6#include <linux/kernel.h>
7#include <linux/module.h>
8#include <linux/init.h>
9#include <linux/blkdev.h>
10#include <linux/list.h>
11#include <linux/llist.h>
12#include <linux/smp.h>
13#include <linux/cpu.h>
14
15#include <linux/blk-mq.h>
16#include "blk-mq.h"
17
18static LIST_HEAD(blk_mq_cpu_notify_list);
19static DEFINE_RAW_SPINLOCK(blk_mq_cpu_notify_lock);
20
21static int blk_mq_main_cpu_notify(struct notifier_block *self,
22				  unsigned long action, void *hcpu)
23{
24	unsigned int cpu = (unsigned long) hcpu;
25	struct blk_mq_cpu_notifier *notify;
26	int ret = NOTIFY_OK;
27
28	raw_spin_lock(&blk_mq_cpu_notify_lock);
29
30	list_for_each_entry(notify, &blk_mq_cpu_notify_list, list) {
31		ret = notify->notify(notify->data, action, cpu);
32		if (ret != NOTIFY_OK)
33			break;
34	}
35
36	raw_spin_unlock(&blk_mq_cpu_notify_lock);
37	return ret;
38}
39
40void blk_mq_register_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
41{
42	BUG_ON(!notifier->notify);
43
44	raw_spin_lock(&blk_mq_cpu_notify_lock);
45	list_add_tail(&notifier->list, &blk_mq_cpu_notify_list);
46	raw_spin_unlock(&blk_mq_cpu_notify_lock);
47}
48
49void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
50{
51	raw_spin_lock(&blk_mq_cpu_notify_lock);
52	list_del(&notifier->list);
53	raw_spin_unlock(&blk_mq_cpu_notify_lock);
54}
55
56void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
57			      int (*fn)(void *, unsigned long, unsigned int),
58			      void *data)
59{
60	notifier->notify = fn;
61	notifier->data = data;
62}
63
64void __init blk_mq_cpu_init(void)
65{
66	hotcpu_notifier(blk_mq_main_cpu_notify, 0);
67}
68