Add the missing __must_hold() annotations. Enable lock context analysis in
the Makefile.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/block/nbd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index fe63f3c55d0d..28bb89bc7de3 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1469,6 +1469,7 @@ static void nbd_config_put(struct nbd_device *nbd)
 }
 
 static int nbd_start_device(struct nbd_device *nbd)
+	__must_hold(&nbd->config_lock)
 {
 	struct nbd_config *config = nbd->config;
 	int num_connections = config->num_connections;
@@ -1541,6 +1542,7 @@ static int nbd_start_device(struct nbd_device *nbd)
 }
 
 static int nbd_start_device_ioctl(struct nbd_device *nbd)
+	__must_hold(nbd->config_lock)
 {
 	struct nbd_config *config = nbd->config;
 	int ret;
@@ -1592,6 +1594,7 @@ static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
 /* Must be called with config_lock held */
 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
 		       unsigned int cmd, unsigned long arg)
+	__must_hold(nbd->config_lock)
 {
 	struct nbd_config *config = nbd->config;
 	loff_t bytesize;