[3/3] nvme: Fix queue freeze and limits lock order

Commit Message

Damien Le Moal Jan. 4, 2025, 1:25 p.m. UTC

Modify the functions nvme_update_ns_info_generic(),
nvme_update_ns_info_block() and nvme_update_ns_info() to freeze a
namespace queue using blk_mq_freeze_queue() after starting the queue
limits update with queue_limits_start_update() so that the queue
freezing is always done after obtaining the device queue limits lock (as
per the block layer convention for sysfs attributes).

Fixes: e6c9b130d681 ("nvme: use the atomic queue limits update API")
Cc: [e-mail]
Signed-off-by: Damien Le Moal <[e-mail]>
---
 drivers/nvme/host/core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Christoph Hellwig Jan. 6, 2025, 8:31 a.m. UTC | #1

On Sat, Jan 04, 2025 at 10:25:22PM +0900, Damien Le Moal wrote:
> Modify the functions nvme_update_ns_info_generic(),
> nvme_update_ns_info_block() and nvme_update_ns_info() to freeze a
> namespace queue using blk_mq_freeze_queue() after starting the queue
> limits update with queue_limits_start_update() so that the queue
> freezing is always done after obtaining the device queue limits lock (as
> per the block layer convention for sysfs attributes).

FYI, there's a few more like this.  In my WIP series I've basically
made the normal queue_limits_commit_update contain the freeze and add
a special version without the freeze, which makes a lot of this
more obvious.  Let me dust it off even before sorting out the poll
flag so that we have a little more discussion material.

Patch

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a970168a3014..8d4ae36c35fc 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2128,8 +2128,8 @@  static int nvme_update_ns_info_generic(struct nvme_ns *ns,
 	struct queue_limits lim;
 	int ret;
 
-	blk_mq_freeze_queue(ns->disk->queue);
 	lim = queue_limits_start_update(ns->disk->queue);
+	blk_mq_freeze_queue(ns->disk->queue);
 	nvme_set_ctrl_limits(ns->ctrl, &lim);
 	ret = queue_limits_commit_update(ns->disk->queue, &lim);
 	set_disk_ro(ns->disk, nvme_ns_is_readonly(ns, info));
@@ -2177,12 +2177,13 @@  static int nvme_update_ns_info_block(struct nvme_ns *ns,
 			goto out;
 	}
 
+	lim = queue_limits_start_update(ns->disk->queue);
+
 	blk_mq_freeze_queue(ns->disk->queue);
 	ns->head->lba_shift = id->lbaf[lbaf].ds;
 	ns->head->nuse = le64_to_cpu(id->nuse);
 	capacity = nvme_lba_to_sect(ns->head, le64_to_cpu(id->nsze));
 
-	lim = queue_limits_start_update(ns->disk->queue);
 	nvme_set_ctrl_limits(ns->ctrl, &lim);
 	nvme_configure_metadata(ns->ctrl, ns->head, id, nvm, info);
 	nvme_set_chunk_sectors(ns, id, &lim);
@@ -2285,6 +2286,8 @@  static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_ns_info *info)
 		struct queue_limits *ns_lim = &ns->disk->queue->limits;
 		struct queue_limits lim;
 
+		lim = queue_limits_start_update(ns->head->disk->queue);
+
 		blk_mq_freeze_queue(ns->head->disk->queue);
 		/*
 		 * queue_limits mixes values that are the hardware limitations
@@ -2301,7 +2304,6 @@  static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_ns_info *info)
 		 * the splitting limits in to make sure we still obey possibly
 		 * lower limitations of other controllers.
 		 */
-		lim = queue_limits_start_update(ns->head->disk->queue);
 		lim.logical_block_size = ns_lim->logical_block_size;
 		lim.physical_block_size = ns_lim->physical_block_size;
 		lim.io_min = ns_lim->io_min;