[PATCH v2 1/2] media: vsp1: vsp1_dl: Detect double list release

[Jacopo Mondi]

In order to detect invalid usage pattern such as double list_put()
calls, add an 'allocated' flag to each display list. Set the flag
whenever a list is get() and clear it when the list is put(). Warn if a
list not marked as allocated is returned to the pool of available
display lists.

Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@xxxxxxxxxxxxxxxx>
---
 drivers/media/platform/renesas/vsp1/vsp1_dl.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/media/platform/renesas/vsp1/vsp1_dl.c b/drivers/media/platform/renesas/vsp1/vsp1_dl.c
index bb8228b198249943399719b5f37c337fc43eed5b..18617cbb168703b851a9b437fa62f18425934c68 100644
--- a/drivers/media/platform/renesas/vsp1/vsp1_dl.c
+++ b/drivers/media/platform/renesas/vsp1/vsp1_dl.c
@@ -176,6 +176,7 @@ struct vsp1_dl_cmd_pool {
  * @bodies: list of extra display list bodies
  * @pre_cmd: pre command to be issued through extended dl header
  * @post_cmd: post command to be issued through extended dl header
+ * @allocated: flag to detect double list release
  * @has_chain: if true, indicates that there's a partition chain
  * @chain: entry in the display list partition chain
  * @flags: display list flags, a combination of VSP1_DL_FRAME_END_*
@@ -194,6 +195,8 @@ struct vsp1_dl_list {
 	struct vsp1_dl_ext_cmd *pre_cmd;
 	struct vsp1_dl_ext_cmd *post_cmd;
 
+	bool allocated;
+
 	bool has_chain;
 	struct list_head chain;
 
@@ -617,6 +620,7 @@ struct vsp1_dl_list *vsp1_dl_list_get(struct vsp1_dl_manager *dlm)
 		 * display list can assert list_empty() if it is not in a chain.
 		 */
 		INIT_LIST_HEAD(&dl->chain);
+		dl->allocated = true;
 	}
 
 	spin_unlock_irqrestore(&dlm->lock, flags);
@@ -657,6 +661,13 @@ static void __vsp1_dl_list_put(struct vsp1_dl_list *dl)
 	 */
 	dl->body0->num_entries = 0;
 
+	/*
+	 * Return the display list to the 'free' pool. If the list had already
+	 * been returned be loud about it.
+	 */
+	WARN_ON_ONCE(!dl->allocated);
+	dl->allocated = false;
+
 	list_add_tail(&dl->list, &dl->dlm->free);
 }
 

-- 
2.49.0