NVMe: Fix admin queue ring wrap
The tag set queue depth needs to be one less than the h/w queue depth
so we don't wrap the circular buffer. This conforms to the specification
defined "Full Queue" condition.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index a7e5499..30ed2ab 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1271,7 +1271,12 @@
if (!dev->ctrl.admin_q) {
dev->admin_tagset.ops = &nvme_mq_admin_ops;
dev->admin_tagset.nr_hw_queues = 1;
- dev->admin_tagset.queue_depth = NVME_AQ_BLKMQ_DEPTH;
+
+ /*
+ * Subtract one to leave an empty queue entry for 'Full Queue'
+ * condition. See NVM-Express 1.2 specification, section 4.1.2.
+ */
+ dev->admin_tagset.queue_depth = NVME_AQ_BLKMQ_DEPTH - 1;
dev->admin_tagset.timeout = ADMIN_TIMEOUT;
dev->admin_tagset.numa_node = dev_to_node(dev->dev);
dev->admin_tagset.cmd_size = nvme_cmd_size(dev);