NVMe: RCU protected access to io queues

This adds rcu protected access to nvme_queue to fix a race between a
surprise removal freeing the queue and a thread with open reference on
a NVMe block device using that queue.

The queues do not need to be rcu protected during the initialization or
shutdown parts, so I've added a helper function for raw deferencing
to get around the sparse errors.

There is still a hole in the IOCTL path for the same problem, which is
fixed in a subsequent patch.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 69ae03f6eb15..98d367b06f9c 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -73,7 +73,7 @@ enum {
  */
 struct nvme_dev {
         struct list_head node;
-        struct nvme_queue **queues;
+        struct nvme_queue __rcu **queues;
         u32 __iomem *dbs;
         struct pci_dev *pci_dev;
         struct dma_pool *prp_page_pool;