[PATCH 1/4] media: videobuf2: finish prepared buffers in VIDIOC_REMOVE_BUFS

[Karl Mehltretter <kmehltretter@gmail.com>]

VIDIOC_PREPARE_BUF leaves a buffer DEQUEUED after calling buf_prepare()
and the prepare() memory operation. VIDIOC_REMOVE_BUFS accepts that state
but frees the buffer without calling the matching finish operations.

With VIDEO_ADV_DEBUG, vivid reports:

  unbalanced counters for queue 000000009fa716f8, buffer 0:
       buf_prepare: 1 buf_finish: 0
       prepare: 1 finish: 0

Finish prepared buffers before freeing them, as queue cancellation does.

Fixes: a3293a85381e ("media: v4l2: Add REMOVE_BUFS ioctl")
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
 drivers/media/common/videobuf2/videobuf2-core.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index b0a6084f17573..460eaf4e82f78 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -1746,6 +1746,19 @@ int vb2_core_remove_bufs(struct vb2_queue *q, unsigned int start, unsigned int c
 			goto unlock;
 		}
 	}
+
+	/* A buffer can be prepared without being queued. Finish it first. */
+	for (i = start; i < start + count; i++) {
+		struct vb2_buffer *vb = vb2_get_buffer(q, i);
+
+		if (!vb->prepared)
+			continue;
+
+		__vb2_buf_mem_finish(vb);
+		call_void_vb_qop(vb, buf_finish, vb);
+		vb->prepared = 0;
+	}
+
 	__vb2_queue_free(q, start, count);
 	dprintk(q, 2, "%u buffers removed\n", count);
 
-- 
2.47.3