V4L/DVB (6342): ivtv: fix circular locking (bug 9037)

If you try to access the video device from within an udev rule,
then you get into a circular locking situation.

Changed the driver to postpone the registration of the devices until
everything else has been fully initialized, so that the newly created
device can be used immediately.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 58 insertions, 42 deletions

diff --git a/drivers/media/video/ivtv/ivtv-streams.c b/drivers/media/video/ivtv/ivtv-streams.c
index ff4cb16a343..6c954b36ee8 100644
--- a/drivers/media/video/ivtv/ivtv-streams.c
+++ b/drivers/media/video/ivtv/ivtv-streams.c
@@ -166,10 +166,9 @@ static void ivtv_stream_init(struct ivtv *itv, int type)
 	ivtv_queue_init(&s->q_io);
 }
 
-static int ivtv_reg_dev(struct ivtv *itv, int type)
+static int ivtv_prep_dev(struct ivtv *itv, int type)
 {
 	struct ivtv_stream *s = &itv->streams[type];
-	int vfl_type = ivtv_stream_info[type].vfl_type;
 	int minor_offset = ivtv_stream_info[type].minor_offset;
 	int minor;
 
@@ -187,15 +186,12 @@ static int ivtv_reg_dev(struct ivtv *itv, int type)
 	if (type >= IVTV_DEC_STREAM_TYPE_MPG && !(itv->v4l2_cap & V4L2_CAP_VIDEO_OUTPUT))
 		return 0;
 
-	if (minor_offset >= 0)
-		/* card number + user defined offset + device offset */
-		minor = itv->num + ivtv_first_minor + minor_offset;
-	else
-		minor = -1;
+	/* card number + user defined offset + device offset */
+	minor = itv->num + ivtv_first_minor + minor_offset;
 
 	/* User explicitly selected 0 buffers for these streams, so don't
 	   create them. */
-	if (minor >= 0 && ivtv_stream_info[type].dma != PCI_DMA_NONE &&
+	if (ivtv_stream_info[type].dma != PCI_DMA_NONE &&
 	    itv->options.kilobytes[type] == 0) {
 		IVTV_INFO("Disabled %s device\n", ivtv_stream_info[type].name);
 		return 0;
@@ -223,21 +219,53 @@ static int ivtv_reg_dev(struct ivtv *itv, int type)
 	s->v4l2dev->fops = ivtv_stream_info[type].fops;
 	s->v4l2dev->release = video_device_release;
 
-	if (minor >= 0) {
-		/* Register device. First try the desired minor, then any free one. */
-		if (video_register_device(s->v4l2dev, vfl_type, minor) &&
-		    video_register_device(s->v4l2dev, vfl_type, -1)) {
-			IVTV_ERR("Couldn't register v4l2 device for %s minor %d\n",
-					s->name, minor);
-			video_device_release(s->v4l2dev);
-			s->v4l2dev = NULL;
-			return -ENOMEM;
-		}
+	return 0;
+}
+
+/* Initialize v4l2 variables and prepare v4l2 devices */
+int ivtv_streams_setup(struct ivtv *itv)
+{
+	int type;
+
+	/* Setup V4L2 Devices */
+	for (type = 0; type < IVTV_MAX_STREAMS; type++) {
+		/* Prepare device */
+		if (ivtv_prep_dev(itv, type))
+			break;
+
+		if (itv->streams[type].v4l2dev == NULL)
+			continue;
+
+		/* Allocate Stream */
+		if (ivtv_stream_alloc(&itv->streams[type]))
+			break;
 	}
-	else {
-		/* Don't register a 'hidden' stream (OSD) */
-		IVTV_INFO("Created framebuffer stream for %s\n", s->name);
+	if (type == IVTV_MAX_STREAMS)
 		return 0;
+
+	/* One or more streams could not be initialized. Clean 'em all up. */
+	ivtv_streams_cleanup(itv);
+	return -ENOMEM;
+}
+
+static int ivtv_reg_dev(struct ivtv *itv, int type)
+{
+	struct ivtv_stream *s = &itv->streams[type];
+	int vfl_type = ivtv_stream_info[type].vfl_type;
+	int minor;
+
+	if (s->v4l2dev == NULL)
+		return 0;
+
+	minor = s->v4l2dev->minor;
+	/* Register device. First try the desired minor, then any free one. */
+	if (video_register_device(s->v4l2dev, vfl_type, minor) &&
+			video_register_device(s->v4l2dev, vfl_type, -1)) {
+		IVTV_ERR("Couldn't register v4l2 device for %s minor %d\n",
+				s->name, minor);
+		video_device_release(s->v4l2dev);
+		s->v4l2dev = NULL;
+		return -ENOMEM;
 	}
 
 	switch (vfl_type) {
@@ -262,27 +290,18 @@ static int ivtv_reg_dev(struct ivtv *itv, int type)
 	return 0;
 }
 
-/* Initialize v4l2 variables and register v4l2 devices */
-int ivtv_streams_setup(struct ivtv *itv)
+/* Register v4l2 devices */
+int ivtv_streams_register(struct ivtv *itv)
 {
 	int type;
+	int err = 0;
 
-	/* Setup V4L2 Devices */
-	for (type = 0; type < IVTV_MAX_STREAMS; type++) {
-		/* Register Device */
-		if (ivtv_reg_dev(itv, type))
-			break;
-
-		if (itv->streams[type].v4l2dev == NULL)
-			continue;
+	/* Register V4L2 devices */
+	for (type = 0; type < IVTV_MAX_STREAMS; type++)
+		err |= ivtv_reg_dev(itv, type);
 
-		/* Allocate Stream */
-		if (ivtv_stream_alloc(&itv->streams[type]))
-			break;
-	}
-	if (type == IVTV_MAX_STREAMS) {
+	if (err == 0)
 		return 0;
-	}
 
 	/* One or more streams could not be initialized. Clean 'em all up. */
 	ivtv_streams_cleanup(itv);
@@ -303,11 +322,8 @@ void ivtv_streams_cleanup(struct ivtv *itv)
 			continue;
 
 		ivtv_stream_free(&itv->streams[type]);
-		/* Free Device */
-		if (vdev->minor == -1) /* 'Hidden' never registered stream (OSD) */
-			video_device_release(vdev);
-		else    /* All others, just unregister. */
-			video_unregister_device(vdev);
+		/* Unregister device */
+		video_unregister_device(vdev);
 	}
 }