[media] v4l: ctrls: Provide an unlocked variant of v4l2_ctrl_modify_range()

Drivers may use the v4l2_ctrl_modify_range() internally as part of other
operations that need to be both serialised using a driver's lock which can
also be used to serialise access to the control handler. Provide an unlocked
version of the function, __v4l2_ctrl_modify_range() which then may be used
by drivers for the purpose.
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -3213,12 +3213,14 @@ void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl, v4l2_ctrl_notify_fnc notify, void
 }
 EXPORT_SYMBOL(v4l2_ctrl_notify);
 
-int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
+int __v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
 			s64 min, s64 max, u64 step, s64 def)
 {
 	int ret;
 	struct v4l2_ext_control c;
 
+	lockdep_assert_held(ctrl->handler->lock);
+
 	switch (ctrl->type) {
 	case V4L2_CTRL_TYPE_INTEGER:
 	case V4L2_CTRL_TYPE_INTEGER64:
@@ -3237,7 +3239,6 @@ int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
 	default:
 		return -EINVAL;
 	}
-	v4l2_ctrl_lock(ctrl);
 	ctrl->minimum = min;
 	ctrl->maximum = max;
 	ctrl->step = step;
@@ -3249,10 +3250,9 @@ int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
 		ret = set_ctrl(NULL, ctrl, &c, V4L2_EVENT_CTRL_CH_RANGE);
 	else
 		send_event(NULL, ctrl, V4L2_EVENT_CTRL_CH_RANGE);
-	v4l2_ctrl_unlock(ctrl);
 	return ret;
 }
-EXPORT_SYMBOL(v4l2_ctrl_modify_range);
+EXPORT_SYMBOL(__v4l2_ctrl_modify_range);
 
 static int v4l2_ctrl_add_event(struct v4l2_subscribed_event *sev, unsigned elems)
 {

include/media/v4l2-ctrls.h

@@ -620,6 +620,11 @@ void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool active);
   */
 void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed);
 
+
+/** __v4l2_ctrl_modify_range() - Unlocked variant of v4l2_ctrl_modify_range() */
+int __v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
+			     s64 min, s64 max, u64 step, s64 def);
+
 /** v4l2_ctrl_modify_range() - Update the range of a control.
   * @ctrl:	The control to update.
   * @min:	The control's minimum value.
@@ -637,8 +642,17 @@ void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed);
   * This function assumes that the control handler is not locked and will
   * take the lock itself.
   */
-int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
-			s64 min, s64 max, u64 step, s64 def);
+static inline int v4l2_ctrl_modify_range(struct v4l2_ctrl *ctrl,
+					 s64 min, s64 max, u64 step, s64 def)
+{
+	int rval;
+
+	v4l2_ctrl_lock(ctrl);
+	rval = __v4l2_ctrl_modify_range(ctrl, min, max, step, def);
+	v4l2_ctrl_unlock(ctrl);
+
+	return rval;
+}
 
 /** v4l2_ctrl_notify() - Function to set a notify callback for a control.
   * @ctrl:	The control.