From 2a6751e052ab4789630bc889c814037068723bc1 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Fri, 10 May 2024 13:23:11 -0700
Subject: [PATCH] nbd: Improve the documentation of the locking assumptions
Document locking assumptions with lockdep_assert_held() instead of source
code comments. The advantage of lockdep_assert_held() is that it is
verified at runtime if lockdep is enabled in the kernel config.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240510202313.25209-4-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
drivers/block/nbd.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 90760f27824df..05f69710afe80 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -588,7 +588,6 @@ static inline int was_interrupted(int result)
return result == -ERESTARTSYS || result == -EINTR;
}
-/* always call with the tx_lock held */
static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
@@ -605,6 +604,9 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
u32 nbd_cmd_flags = 0;
int sent = nsock->sent, skip = 0;
+ lockdep_assert_held(&cmd->lock);
+ lockdep_assert_held(&nsock->tx_lock);
+
iov_iter_kvec(&from, ITER_SOURCE, &iov, 1, sizeof(request));
type = req_to_nbd_cmd_type(req);
@@ -1015,6 +1017,8 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
struct nbd_sock *nsock;
int ret;
+ lockdep_assert_held(&cmd->lock);
+
config = nbd_get_config_unlocked(nbd);
if (!config) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
--
2.30.2