media: sta2x11: Add video_device and vb2_queue locks

Currently, this driver does not serialize its video4linux
ioctls, which is a bug, as race conditions might appear.

In addition, video_device and vb2_queue locks are now both
mandatory. Add them, and implement wait_prepare and
wait_finish.

To stay on the safe side, this commit uses a single mutex
for both locks. Better latency can be obtained by separating
these if needed.
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/pci/sta2x11/sta2x11_vip.c

@@ -145,6 +145,7 @@ struct sta2x11_vip {
 	unsigned int sequence;
 	struct vip_buffer *active; /* current active buffer */
 	spinlock_t lock; /* Used in videobuf2 callback */
+	struct mutex v4l_lock;
 
 	/* Interrupt counters */
 	int tcount, bcount;
@@ -385,6 +386,8 @@ static const struct vb2_ops vip_video_qops = {
 	.buf_queue		= buffer_queue,
 	.start_streaming	= start_streaming,
 	.stop_streaming		= stop_streaming,
+	.wait_prepare		= vb2_ops_wait_prepare,
+	.wait_finish		= vb2_ops_wait_finish,
 };
 
 
@@ -870,6 +873,7 @@ static int sta2x11_vip_init_buffer(struct sta2x11_vip *vip)
 	vip->vb_vidq.mem_ops = &vb2_dma_contig_memops;
 	vip->vb_vidq.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
 	vip->vb_vidq.dev = &vip->pdev->dev;
+	vip->vb_vidq.lock = &vip->v4l_lock;
 	err = vb2_queue_init(&vip->vb_vidq);
 	if (err)
 		return err;
@@ -1034,6 +1038,7 @@ static int sta2x11_vip_init_one(struct pci_dev *pdev,
 	vip->std = V4L2_STD_PAL;
 	vip->format = formats_50[0];
 	vip->config = config;
+	mutex_init(&vip->v4l_lock);
 
 	ret = sta2x11_vip_init_controls(vip);
 	if (ret)
@@ -1080,6 +1085,7 @@ static int sta2x11_vip_init_one(struct pci_dev *pdev,
 	vip->video_dev = video_dev_template;
 	vip->video_dev.v4l2_dev = &vip->v4l2_dev;
 	vip->video_dev.queue = &vip->vb_vidq;
+	vip->video_dev.lock = &vip->v4l_lock;
 	video_set_drvdata(&vip->video_dev, vip);
 
 	ret = video_register_device(&vip->video_dev, VFL_TYPE_GRABBER, -1);