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@ideasonboard.com>
---
 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

Hi Jacopo,

On Mon, Jun 16, 2025 at 06:30:37PM +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+renesas@ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

> ---
>  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);
>  }
>  

-- 
Regards,

Laurent Pinchart