nvme: remove dead controllers from a work item

BugLink: http://bugs.launchpad.net/bugs/1531539

Compared to the kthread this gives us multiple call prevention for free.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit 5c8809e6)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/nvme/host/pci.c

@@ -80,7 +80,7 @@ struct nvme_iod;
 static int nvme_reset(struct nvme_dev *dev);
 static void nvme_process_cq(struct nvme_queue *nvmeq);
 static void nvme_unmap_data(struct nvme_dev *dev, struct nvme_iod *iod);
-static void nvme_dead_ctrl(struct nvme_dev *dev);
+static void nvme_remove_dead_ctrl(struct nvme_dev *dev);
 static void nvme_dev_shutdown(struct nvme_dev *dev);
 
 struct async_cmd_info {
@@ -113,6 +113,7 @@ struct nvme_dev {
 	void __iomem *bar;
 	struct work_struct reset_work;
 	struct work_struct scan_work;
+	struct work_struct remove_work;
 	struct mutex shutdown_lock;
 	bool subsystem;
 	void __iomem *cmb;
@@ -2230,31 +2231,25 @@ static void nvme_reset_work(struct work_struct *work)
  unmap:
 	nvme_dev_unmap(dev);
  out:
-	if (!work_pending(&dev->reset_work))
-		nvme_dead_ctrl(dev);
+	nvme_remove_dead_ctrl(dev);
 }
 
-static int nvme_remove_dead_ctrl(void *arg)
+static void nvme_remove_dead_ctrl_work(struct work_struct *work)
 {
-	struct nvme_dev *dev = (struct nvme_dev *)arg;
+	struct nvme_dev *dev = container_of(work, struct nvme_dev, remove_work);
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 
 	if (pci_get_drvdata(pdev))
 		pci_stop_and_remove_bus_device_locked(pdev);
 	nvme_put_ctrl(&dev->ctrl);
-	return 0;
 }
 
-static void nvme_dead_ctrl(struct nvme_dev *dev)
+static void nvme_remove_dead_ctrl(struct nvme_dev *dev)
 {
-	dev_warn(dev->dev, "Device failed to resume\n");
+	dev_warn(dev->dev, "Removing after probe failure\n");
 	kref_get(&dev->ctrl.kref);
-	if (IS_ERR(kthread_run(nvme_remove_dead_ctrl, dev, "nvme%d",
-						dev->ctrl.instance))) {
-		dev_err(dev->dev,
-			"Failed to start controller remove task\n");
+	if (!schedule_work(&dev->remove_work))
 		nvme_put_ctrl(&dev->ctrl);
-	}
 }
 
 static int nvme_reset(struct nvme_dev *dev)
@@ -2335,6 +2330,7 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	INIT_LIST_HEAD(&dev->node);
 	INIT_WORK(&dev->scan_work, nvme_dev_scan);
 	INIT_WORK(&dev->reset_work, nvme_reset_work);
+	INIT_WORK(&dev->remove_work, nvme_remove_dead_ctrl_work);
 	mutex_init(&dev->shutdown_lock);
 
 	result = nvme_setup_prp_pools(dev);