NVMe: Memory barrier before queue_count is incremented
Protects against reordering and/or preempting which would allow the
kthread to access the queue descriptor before it is set up
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
index 9682e29..cae7cac 100644
--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -1453,9 +1453,12 @@
nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
nvmeq->q_depth = depth;
nvmeq->qid = qid;
- dev->queue_count++;
dev->queues[qid] = nvmeq;
+ /* make sure queue descriptor is set before queue count, for kthread */
+ mb();
+ dev->queue_count++;
+
return nvmeq;
free_cqdma: