1 files changed, 67 insertions, 0 deletions
diff --git a/block/blk-mq-cpu.c b/block/blk-mq-cpu.c
new file mode 100644
index 000000000..bb3ed488f
--- /dev/null
+++ b/block/blk-mq-cpu.c
@@ -0,0 +1,67 @@
+/*
+ * CPU notifier helper code for blk-mq
+ *
+ * Copyright (C) 2013-2014 Jens Axboe
+ */
+#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_RAW_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;
+	int ret = NOTIFY_OK;
+
+	raw_spin_lock(&blk_mq_cpu_notify_lock);
+
+	list_for_each_entry(notify, &blk_mq_cpu_notify_list, list) {
+		ret = notify->notify(notify->data, action, cpu);
+		if (ret != NOTIFY_OK)
+			break;
+	}
+
+	raw_spin_unlock(&blk_mq_cpu_notify_lock);
+	return ret;
+}
+
+void blk_mq_register_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
+{
+	BUG_ON(!notifier->notify);
+
+	raw_spin_lock(&blk_mq_cpu_notify_lock);
+	list_add_tail(&notifier->list, &blk_mq_cpu_notify_list);
+	raw_spin_unlock(&blk_mq_cpu_notify_lock);
+}
+
+void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
+{
+	raw_spin_lock(&blk_mq_cpu_notify_lock);
+	list_del(&notifier->list);
+	raw_spin_unlock(&blk_mq_cpu_notify_lock);
+}
+
+void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
+			      int (*fn)(void *, unsigned long, unsigned int),
+			      void *data)
+{
+	notifier->notify = fn;
+	notifier->data = data;
+}
+
+void __init blk_mq_cpu_init(void)
+{
+	hotcpu_notifier(blk_mq_main_cpu_notify, 0);
+}