[media.git/next] media: vsp1: vsp1_dl: Detect double list release

[media-ci]

On Mon Jun 16 18:30:37 2025 +0200, Jacopo Mondi wrote:
> 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+rene...@ideasonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
> Link: 
> https://lore.kernel.org/r/20250616-vsp1_dl_list_count-v2-1-7d3f43fb1...@ideasonboard.com
> Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> Signed-off-by: Hans Verkuil <hverk...@xs4all.nl>

Patch committed.

Thanks,
Hans Verkuil

 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 bb8228b19824..18617cbb1687 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);
 }