staging: comedi: Add lockdep_assert_held() calls for dev->mutex

Lots of functions in the core comedi module expect the mutex in `struct
comedi_device` to be held, so add calls to `lockdep_assert_held()` to
check and document that.  An unusual case is the calls to
`lockdep_assert_held()` after successful return from
`comedi_alloc_board_minor()` which allocates a `struct comedi_device`
and returns with its mutex locked.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
index f693c2c0bec3..d2c8cc72a99d 100644
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -211,6 +211,8 @@ int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
 {
 	struct comedi_async *async = s->async;
 
+	lockdep_assert_held(&dev->mutex);
+
 	/* Round up new_size to multiple of PAGE_SIZE */
 	new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;