Commit b9afca3e authored by Dan McLeran's avatar Dan McLeran Committed by Matthew Wilcox
Browse files

NVMe: Start-stop nvme_thread during device add-remove. 



Done to ensure nvme_thread is not running when there
are no devices to poll.

Signed-off-by: default avatarDan McLeran <daniel.mcleran@intel.com>
Signed-off-by: default avatarMatthew Wilcox <matthew.r.wilcox@intel.com>
parent b355084a

drivers/block/nvme-core.c

+42 −14
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ static DEFINE_SPINLOCK(dev_list_lock); 
static LIST_HEAD(dev_list);

static struct task_struct *nvme_thread;

static struct workqueue_struct *nvme_workq;

static wait_queue_head_t nvme_kthread_wait;



static void nvme_reset_failed_dev(struct work_struct *ws);
@@ -2374,6 +2375,26 @@ static void nvme_disable_io_queues(struct nvme_dev *dev) 
	kthread_stop(kworker_task);

}



/*

* Remove the node from the device list and check

* for whether or not we need to stop the nvme_thread.

*/

static void nvme_dev_list_remove(struct nvme_dev *dev)

{

	struct task_struct *tmp = NULL;



	spin_lock(&dev_list_lock);

	list_del_init(&dev->node);

	if (list_empty(&dev_list) && !IS_ERR_OR_NULL(nvme_thread)) {

		tmp = nvme_thread;

		nvme_thread = NULL;

	}

	spin_unlock(&dev_list_lock);



	if (tmp)

		kthread_stop(tmp);

}



static void nvme_dev_shutdown(struct nvme_dev *dev)

{

	int i;
@@ -2381,9 +2402,7 @@ static void nvme_dev_shutdown(struct nvme_dev *dev) 
	dev->initialized = 0;

	unregister_hotcpu_notifier(&dev->nb);



	spin_lock(&dev_list_lock);

	list_del_init(&dev->node);

	spin_unlock(&dev_list_lock);

	nvme_dev_list_remove(dev);



	if (!dev->bar || (dev->bar && readl(&dev->bar->csts) == -1)) {

		for (i = dev->queue_count - 1; i >= 0; i--) {
@@ -2524,6 +2543,7 @@ static const struct file_operations nvme_dev_fops = { 
static int nvme_dev_start(struct nvme_dev *dev)

{

	int result;

	bool start_thread = false;



	result = nvme_dev_map(dev);

	if (result)
@@ -2534,9 +2554,24 @@ static int nvme_dev_start(struct nvme_dev *dev) 
		goto unmap;



	spin_lock(&dev_list_lock);

	if (list_empty(&dev_list) && IS_ERR_OR_NULL(nvme_thread)) {

		start_thread = true;

		nvme_thread = NULL;

	}

	list_add(&dev->node, &dev_list);

	spin_unlock(&dev_list_lock);



	if (start_thread) {

		nvme_thread = kthread_run(nvme_kthread, NULL, "nvme");

		wake_up(&nvme_kthread_wait);

	} else

		wait_event_killable(nvme_kthread_wait, nvme_thread);



	if (IS_ERR_OR_NULL(nvme_thread)) {

		result = nvme_thread ? PTR_ERR(nvme_thread) : -EINTR;

		goto disable;

	}



	result = nvme_setup_io_queues(dev);

	if (result && result != -EBUSY)

		goto disable;
@@ -2545,9 +2580,7 @@ static int nvme_dev_start(struct nvme_dev *dev) 


 disable:

	nvme_disable_queue(dev, 0);

	spin_lock(&dev_list_lock);

	list_del_init(&dev->node);

	spin_unlock(&dev_list_lock);

	nvme_dev_list_remove(dev);

 unmap:

	nvme_dev_unmap(dev);

	return result;
@@ -2776,14 +2809,11 @@ static int __init nvme_init(void) 
{

	int result;



	nvme_thread = kthread_run(nvme_kthread, NULL, "nvme");

	if (IS_ERR(nvme_thread))

		return PTR_ERR(nvme_thread);

	init_waitqueue_head(&nvme_kthread_wait);



	result = -ENOMEM;

	nvme_workq = create_singlethread_workqueue("nvme");

	if (!nvme_workq)

		goto kill_kthread;

		return -ENOMEM;



	result = register_blkdev(nvme_major, "nvme");

	if (result < 0)
@@ -2800,8 +2830,6 @@ static int __init nvme_init(void) 
	unregister_blkdev(nvme_major, "nvme");

 kill_workq:

	destroy_workqueue(nvme_workq);

 kill_kthread:

	kthread_stop(nvme_thread);

	return result;

}
@@ -2810,7 +2838,7 @@ static void __exit nvme_exit(void) 
	pci_unregister_driver(&nvme_driver);

	unregister_blkdev(nvme_major, "nvme");

	destroy_workqueue(nvme_workq);

	kthread_stop(nvme_thread);

	BUG_ON(nvme_thread && !IS_ERR(nvme_thread));

}



MODULE_AUTHOR("Matthew Wilcox <willy@linux.intel.com>");