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From: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Date: Mon, 18 Mar 2024 11:50:59 +0200
Subject: [PATCH v2] media: mc: Fix graph walk in media_pipeline_start
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Message-Id: <20240318-mc-graph-fix-v2-1-416a22bf7ce8@ideasonboard.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>, 
 Laurent Pinchart <laurent.pinchart@ideasonboard.com>, 
 Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, 
 Naushir Patuck <naush@raspberrypi.com>, 
 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

The graph walk tries to follow all links, even if they are not between
pads. This causes a crash with, e.g. a MEDIA_LNK_FL_ANCILLARY_LINK link.

Fix this by allowing the walk to proceed only for MEDIA_LNK_FL_DATA_LINK
links.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Fixes: ae219872834a ("media: mc: entity: Rewrite media_pipeline_start()")
---
Changes in v2:
- Move the check a bit earlier, so that we don't do a debug print for
  ancillary links using data link fields.
- Link to v1: https://lore.kernel.org/r/20240315-mc-graph-fix-v1-1-91d59d752614@ideasonboard.com
---
 drivers/media/mc/mc-entity.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index 543a392f8635..3fd3dab81ea1 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -615,6 +615,12 @@ static int media_pipeline_explore_next_link(struct media_pipeline *pipe,
 	link = list_entry(entry->links, typeof(*link), list);
 	media_pipeline_walk_pop(walk);
 
+	if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) != MEDIA_LNK_FL_DATA_LINK) {
+		dev_dbg(walk->mdev->dev,
+			"media pipeline: skipping link (not data-link)\n");
+		return 0;
+	}
+
 	dev_dbg(walk->mdev->dev,
 		"media pipeline: exploring link '%s':%u -> '%s':%u\n",
 		link->source->entity->name, link->source->index,

---
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
change-id: 20240315-mc-graph-fix-8a2a245d7346

Best regards,
-- 
Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>