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: Dan McLeran <daniel.mcleran@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 7c57b1d..2d69bfe 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -64,6 +64,7 @@
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 @@
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 @@
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 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 @@
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 @@
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 @@
{
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 @@
unregister_blkdev(nvme_major, "nvme");
kill_workq:
destroy_workqueue(nvme_workq);
- kill_kthread:
- kthread_stop(nvme_thread);
return result;
}
@@ -2810,7 +2838,7 @@
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>");