blk-mq-cpu.c

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/list.h>
#include <linux/llist.h>
#include <linux/smp.h>
#include <linux/cpu.h>

#include <linux/blk-mq.h>
#include "blk-mq.h"

static LIST_HEAD(blk_mq_cpu_notify_list);
static DEFINE_SPINLOCK(blk_mq_cpu_notify_lock);

static int blk_mq_main_cpu_notify(struct notifier_block *self,
				  unsigned long action, void *hcpu)
{
	unsigned int cpu = (unsigned long) hcpu;
	struct blk_mq_cpu_notifier *notify;

	spin_lock(&blk_mq_cpu_notify_lock);

	list_for_each_entry(notify, &blk_mq_cpu_notify_list, list)
		notify->notify(notify->data, action, cpu);

	spin_unlock(&blk_mq_cpu_notify_lock);
	return NOTIFY_OK;
}

static void blk_mq_cpu_notify(void *data, unsigned long action,
			      unsigned int cpu)
{
	if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
		/*
		 * If the CPU goes away, ensure that we run any pending
		 * completions.
		 */
		struct llist_node *node;
		struct request *rq;

		local_irq_disable();

		node = llist_del_all(&per_cpu(ipi_lists, cpu));
		while (node) {
			struct llist_node *next = node->next;

			rq = llist_entry(node, struct request, ll_list);
			__blk_mq_end_io(rq, rq->errors);
			node = next;
		}

		local_irq_enable();
	}
}

static struct notifier_block __cpuinitdata blk_mq_main_cpu_notifier = {
	.notifier_call	= blk_mq_main_cpu_notify,
};

void blk_mq_register_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
{
	BUG_ON(!notifier->notify);

	spin_lock(&blk_mq_cpu_notify_lock);
	list_add_tail(&notifier->list, &blk_mq_cpu_notify_list);
	spin_unlock(&blk_mq_cpu_notify_lock);
}

void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
{
	spin_lock(&blk_mq_cpu_notify_lock);
	list_del(&notifier->list);
	spin_unlock(&blk_mq_cpu_notify_lock);
}

void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
			      void (*fn)(void *, unsigned long, unsigned int),
			      void *data)
{
	notifier->notify = fn;
	notifier->data = data;
}

static struct blk_mq_cpu_notifier __cpuinitdata cpu_notifier = {
	.notify = blk_mq_cpu_notify,
};

void __init blk_mq_cpu_init(void)
{
	register_hotcpu_notifier(&blk_mq_main_cpu_notifier);
	blk_mq_register_cpu_notifier(&cpu_notifier);
}