NVMe: Fix namespace removal deadlock
This patch makes nvme namespace removal lockless. It is up to the caller
to ensure no active namespace scanning is occuring. To ensure no scan
work occurs, the nvme pci driver adds a removing state to the controller
device to avoid queueing scan work during removal. The work is flushed
after setting the state, so no new scan work can be queued.
The lockless removal allows the driver to cleanup a namespace
request_queue if the controller fails during removal. Previously this
could deadlock trying to acquire the namespace mutex in order to handle
such events.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 2ea3e39..122f803 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -120,6 +120,7 @@
unsigned long flags;
#define NVME_CTRL_RESETTING 0
+#define NVME_CTRL_REMOVING 1
struct nvme_ctrl ctrl;
struct completion ioq_wait;
@@ -286,6 +287,17 @@
return 0;
}
+static void nvme_queue_scan(struct nvme_dev *dev)
+{
+ /*
+ * Do not queue new scan work when a controller is reset during
+ * removal.
+ */
+ if (test_bit(NVME_CTRL_REMOVING, &dev->flags))
+ return;
+ queue_work(nvme_workq, &dev->scan_work);
+}
+
static void nvme_complete_async_event(struct nvme_dev *dev,
struct nvme_completion *cqe)
{
@@ -300,7 +312,7 @@
switch (result & 0xff07) {
case NVME_AER_NOTICE_NS_CHANGED:
dev_info(dev->dev, "rescanning\n");
- queue_work(nvme_workq, &dev->scan_work);
+ nvme_queue_scan(dev);
default:
dev_warn(dev->dev, "async event result %08x\n", result);
}
@@ -1690,7 +1702,7 @@
return 0;
dev->ctrl.tagset = &dev->tagset;
}
- queue_work(nvme_workq, &dev->scan_work);
+ nvme_queue_scan(dev);
return 0;
}
@@ -2128,6 +2140,7 @@
{
struct nvme_dev *dev = pci_get_drvdata(pdev);
+ set_bit(NVME_CTRL_REMOVING, &dev->flags);
pci_set_drvdata(pdev, NULL);
flush_work(&dev->scan_work);
nvme_remove_namespaces(&dev->ctrl);