NVMe: Fix hot cpu notification dead lock
There is a potential dead lock if a cpu event occurs during nvme probe
since it registered with hot cpu notification. This fixes the race by
having the module register with notification outside of probe rather
than have each device register.
The actual work is done in a scheduled work queue instead of in the
notifier since assigning IO queues has the potential to block if the
driver creates additional queues.
Signed-off-by: Keith Busch <keith.busch@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 2af079e..e0ac121 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -73,6 +73,7 @@
static struct task_struct *nvme_thread;
static struct workqueue_struct *nvme_workq;
static wait_queue_head_t nvme_kthread_wait;
+static struct notifier_block nvme_nb;
static void nvme_reset_failed_dev(struct work_struct *ws);
@@ -2115,14 +2116,25 @@
return 4096 + ((nr_io_queues + 1) * 8 * dev->db_stride);
}
+static void nvme_cpu_workfn(struct work_struct *work)
+{
+ struct nvme_dev *dev = container_of(work, struct nvme_dev, cpu_work);
+ if (dev->initialized)
+ nvme_assign_io_queues(dev);
+}
+
static int nvme_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
- struct nvme_dev *dev = container_of(self, struct nvme_dev, nb);
+ struct nvme_dev *dev;
+
switch (action) {
case CPU_ONLINE:
case CPU_DEAD:
- nvme_assign_io_queues(dev);
+ spin_lock(&dev_list_lock);
+ list_for_each_entry(dev, &dev_list, node)
+ schedule_work(&dev->cpu_work);
+ spin_unlock(&dev_list_lock);
break;
}
return NOTIFY_OK;
@@ -2191,11 +2203,6 @@
nvme_free_queues(dev, nr_io_queues + 1);
nvme_assign_io_queues(dev);
- dev->nb.notifier_call = &nvme_cpu_notify;
- result = register_hotcpu_notifier(&dev->nb);
- if (result)
- goto free_queues;
-
return 0;
free_queues:
@@ -2495,8 +2502,6 @@
int i;
dev->initialized = 0;
- unregister_hotcpu_notifier(&dev->nb);
-
nvme_dev_list_remove(dev);
if (!dev->bar || (dev->bar && readl(&dev->bar->csts) == -1)) {
@@ -2767,6 +2772,7 @@
INIT_LIST_HEAD(&dev->namespaces);
dev->reset_workfn = nvme_reset_failed_dev;
INIT_WORK(&dev->reset_work, nvme_reset_workfn);
+ INIT_WORK(&dev->cpu_work, nvme_cpu_workfn);
dev->pci_dev = pdev;
pci_set_drvdata(pdev, dev);
result = nvme_set_instance(dev);
@@ -2836,6 +2842,7 @@
pci_set_drvdata(pdev, NULL);
flush_work(&dev->reset_work);
+ flush_work(&dev->cpu_work);
misc_deregister(&dev->miscdev);
nvme_dev_remove(dev);
nvme_dev_shutdown(dev);
@@ -2923,11 +2930,18 @@
else if (result > 0)
nvme_major = result;
- result = pci_register_driver(&nvme_driver);
+ nvme_nb.notifier_call = &nvme_cpu_notify;
+ result = register_hotcpu_notifier(&nvme_nb);
if (result)
goto unregister_blkdev;
+
+ result = pci_register_driver(&nvme_driver);
+ if (result)
+ goto unregister_hotcpu;
return 0;
+ unregister_hotcpu:
+ unregister_hotcpu_notifier(&nvme_nb);
unregister_blkdev:
unregister_blkdev(nvme_major, "nvme");
kill_workq:
@@ -2938,6 +2952,7 @@
static void __exit nvme_exit(void)
{
pci_unregister_driver(&nvme_driver);
+ unregister_hotcpu_notifier(&nvme_nb);
unregister_blkdev(nvme_major, "nvme");
destroy_workqueue(nvme_workq);
BUG_ON(nvme_thread && !IS_ERR(nvme_thread));