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authorKeith Busch <keith.busch@intel.com>2014-06-11 11:51:35 -0600
committerMatthew Wilcox <matthew.r.wilcox@intel.com>2014-06-13 10:43:34 -0400
commitf3db22feb5de6b98b7bae924c2d4b6c8d65bedae (patch)
tree1a2fc6e5dd199f15280a40aae824ac41b72177b7
parentbd67608a6127c994e897c49cc4f72d9095925301 (diff)
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>
-rw-r--r--drivers/block/nvme-core.c35
-rw-r--r--include/linux/nvme.h2
2 files changed, 26 insertions, 11 deletions
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 2af079e571fc..e0ac1210fe31 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -73,6 +73,7 @@ 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 struct notifier_block nvme_nb;
static void nvme_reset_failed_dev(struct work_struct *ws);
@@ -2115,14 +2116,25 @@ static size_t db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
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 @@ static int nvme_setup_io_queues(struct nvme_dev *dev)
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 @@ static void nvme_dev_shutdown(struct nvme_dev *dev)
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 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
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 @@ static void nvme_remove(struct pci_dev *pdev)
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 @@ static int __init nvme_init(void)
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 int __init nvme_init(void)
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));
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 8541dd920bb7..2bf403195c09 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -90,7 +90,7 @@ struct nvme_dev {
struct miscdevice miscdev;
work_func_t reset_workfn;
struct work_struct reset_work;
- struct notifier_block nb;
+ struct work_struct cpu_work;
char name[12];
char serial[20];
char model[40];

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