From e3e9d50cd6ed392bb716e35c134d1e82707c51b4 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Mon, 4 Jan 2016 09:10:55 -0700 Subject: [PATCH] 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 Signed-off-by: Jens Axboe --- drivers/nvme/host/pci.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index a7e549969462..30ed2ab2cadb 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -1271,7 +1271,12 @@ static int nvme_alloc_admin_tags(struct nvme_dev *dev) 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); -- 2.20.1