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

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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>
This commit is contained in:
Dan McLeran 2014-04-07 17:10:11 -06:00 committed by Matthew Wilcox
parent b355084a89
commit b9afca3efb
1 changed files with 42 additions and 14 deletions
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56
drivers/block/nvme-core.c
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@ -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>");