[PATCH v3 01/13] media: ipu6: Ensure stream_mutex is acquired when dealing with node list

[Sakari Ailus <sakari.ailus@linux.intel.com>]

The ipu6 isys driver maintains the list of video buffer queues related to
a stream (in ipu6 context streams on the same CSI-2 virtual channel) and
this list is modified through VIDIOC_STREAMON and VIDIOC_STREAMOFF IOCTLs.
Ensure the common mutex is acquired when accessing the linked list, i.e.
the isys device context's stream_mutex.

Add a lockdep assert to ipu6_isys_get_buffer_list() and switch to guard()
while at it as the error handling becomes more simple this way.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/pci/intel/ipu6/ipu6-isys-queue.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/media/pci/intel/ipu6/ipu6-isys-queue.c b/drivers/media/pci/intel/ipu6/ipu6-isys-queue.c
index aa2cf7287477..8f05987cdb4e 100644
--- a/drivers/media/pci/intel/ipu6/ipu6-isys-queue.c
+++ b/drivers/media/pci/intel/ipu6/ipu6-isys-queue.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2013--2024 Intel Corporation
  */
 #include <linux/atomic.h>
+#include <linux/cleanup.h>
 #include <linux/bug.h>
 #include <linux/device.h>
 #include <linux/list.h>
@@ -201,6 +202,8 @@ static int buffer_list_get(struct ipu6_isys_stream *stream,
 	unsigned long flags;
 	unsigned long buf_flag = IPU6_ISYS_BUFFER_LIST_FL_INCOMING;
 
+	lockdep_assert_held(&stream->mutex);
+
 	bl->nbufs = 0;
 	INIT_LIST_HEAD(&bl->head);
 
@@ -294,9 +297,8 @@ static int ipu6_isys_stream_start(struct ipu6_isys_video *av,
 	struct ipu6_isys_buffer_list __bl;
 	int ret;
 
-	mutex_lock(&stream->isys->stream_mutex);
+	guard(mutex)(&stream->isys->stream_mutex);
 	ret = ipu6_isys_video_set_streaming(av, 1, bl);
-	mutex_unlock(&stream->isys->stream_mutex);
 	if (ret)
 		goto out_requeue;
 
@@ -637,10 +639,10 @@ static void stop_streaming(struct vb2_queue *q)
 	mutex_lock(&av->isys->stream_mutex);
 	if (stream->nr_streaming == stream->nr_queues && stream->streaming)
 		ipu6_isys_video_set_streaming(av, 0, NULL);
+	list_del(&aq->node);
 	mutex_unlock(&av->isys->stream_mutex);
 
 	stream->nr_streaming--;
-	list_del(&aq->node);
 	stream->streaming = 0;
 	mutex_unlock(&stream->mutex);
 
-- 
2.47.3