[PATCH 1/2] s390/con3215: Add __must_hold() attribute to raw3215_make_room()

Add __must_hold() attribute to raw3215_make_room() in order to let
clang's context analysis know that "get_ccwdev_lock(raw->cdev)" must be
held on function entry. This can also be easily verified when inspecting
the function.

Without this annotation this leads to a valid warning when context
analysis is enabled:

drivers/s390/char/con3215.c:485:9: warning:
  expecting spinlock 'raw->cdev->ccwlock' to be held at start of each loop [-Wthread-safety-analysis]
  485 |         while (RAW3215_BUFFER_SIZE - raw->count < length) {

Signed-off-by: Heiko Carstens <[email protected]>
---
 drivers/s390/char/con3215.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index 46265f4fbfd8..57fefa8986d6 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -481,6 +481,7 @@ static unsigned int raw3215_drop(struct raw3215_info *raw)
  */
 static unsigned int raw3215_make_room(struct raw3215_info *raw,
 				      unsigned int length, bool drop)
+	__must_hold(get_ccwdev_lock(raw->cdev))
 {
 	while (RAW3215_BUFFER_SIZE - raw->count < length) {
 		if (drop)
-- 
2.53.0