[PATCHv2 07/10] v4l2-ctrls: use media_request_(un)lock_for_access

[Hans Verkuil]

From: Hans Verkuil <hans.verk...@cisco.com>

When getting control values from a completed request, we have
to protect the request against being re-inited why it is
being accessed by calling media_request_(un)lock_for_access.

Signed-off-by: Hans Verkuil <hans.verk...@cisco.com>
---
 drivers/media/v4l2-core/v4l2-ctrls.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c 
b/drivers/media/v4l2-core/v4l2-ctrls.c
index ccaf3068de6d..cc266a4a6e88 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -3289,11 +3289,10 @@ int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, 
struct media_device *mdev,
                     struct v4l2_ext_controls *cs)
 {
        struct media_request_object *obj = NULL;
+       struct media_request *req = NULL;
        int ret;
 
        if (cs->which == V4L2_CTRL_WHICH_REQUEST_VAL) {
-               struct media_request *req;
-
                if (!mdev || cs->request_fd < 0)
                        return -EINVAL;
 
@@ -3306,11 +3305,18 @@ int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, 
struct media_device *mdev,
                        return -EACCES;
                }
 
+               ret = media_request_lock_for_access(req);
+               if (ret) {
+                       media_request_put(req);
+                       return ret;
+               }
+
                obj = v4l2_ctrls_find_req_obj(hdl, req, false);
-               /* Reference to the request held through obj */
-               media_request_put(req);
-               if (IS_ERR(obj))
+               if (IS_ERR(obj)) {
+                       media_request_unlock_for_access(req);
+                       media_request_put(req);
                        return PTR_ERR(obj);
+               }
 
                hdl = container_of(obj, struct v4l2_ctrl_handler,
                                   req_obj);
@@ -3318,8 +3324,11 @@ int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, 
struct media_device *mdev,
 
        ret = v4l2_g_ext_ctrls_common(hdl, cs);
 
-       if (obj)
+       if (obj) {
+               media_request_unlock_for_access(req);
                media_request_object_put(obj);
+               media_request_put(req);
+       }
        return ret;
 }
 EXPORT_SYMBOL(v4l2_g_ext_ctrls);
-- 
2.18.0