block/blk-mq-cpu.c

   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
  18 static LIST_HEAD(blk_mq_cpu_notify_list);
  19 static DEFINE_RAW_SPINLOCK(blk_mq_cpu_notify_lock);
  20
  21 static 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
  40 void 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
  49 void 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
  56 void 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
  64 void __init blk_mq_cpu_init(void)
  65 {
  66         hotcpu_notifier(blk_mq_main_cpu_notify, 0);
  67 }