This is a note to let you know that I've just added the patch titled
nbd: Improve the documentation of the locking assumptions
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nbd-improve-the-documentation-of-the-locking-assumpt.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7f49b2cf48bfdee465574d940e8e466dc4499bd6
Author: Bart Van Assche <bvanassche@xxxxxxx>
Date: Fri May 10 13:23:11 2024 -0700
nbd: Improve the documentation of the locking assumptions
[ Upstream commit 2a6751e052ab4789630bc889c814037068723bc1 ]
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@xxxxxx>
Cc: Josef Bacik <jbacik@xxxxxx>
Cc: Yu Kuai <yukuai3@xxxxxxxxxx>
Cc: Markus Pargmann <mpa@xxxxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
Link: https://lore.kernel.org/r/20240510202313.25209-4-bvanassche@xxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Stable-dep-of: e56d4b633fff ("nbd: Fix signal handling")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index df738eab02433..a906674f71147 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -569,7 +569,6 @@ 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);
@@ -586,6 +585,9 @@ 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);
@@ -996,6 +998,8 @@ 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),
