V4L/DVB (10083): soc-camera: unify locking, play nicer with videobuf locking
Move mutex from host drivers to camera device object, take into account
videobuf locking.
Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/soc_camera.c b/drivers/media/video/soc_camera.c
index d5613cd..e869670 100644
--- a/drivers/media/video/soc_camera.c
+++ b/drivers/media/video/soc_camera.c
@@ -33,7 +33,6 @@
static LIST_HEAD(hosts);
static LIST_HEAD(devices);
static DEFINE_MUTEX(list_lock);
-static DEFINE_MUTEX(video_lock);
const struct soc_camera_data_format *soc_camera_format_by_fourcc(
struct soc_camera_device *icd, unsigned int fourcc)
@@ -270,8 +269,10 @@
if (!icf)
return -ENOMEM;
- /* Protect against icd->remove() until we module_get() both drivers. */
- mutex_lock(&video_lock);
+ /*
+ * It is safe to dereference these pointers now as long as a user has
+ * the video device open - we are protected by the held cdev reference.
+ */
vdev = video_devdata(file);
icd = container_of(vdev->parent, struct soc_camera_device, dev);
@@ -289,6 +290,9 @@
goto emgi;
}
+ /* Protect against icd->remove() until we module_get() both drivers. */
+ mutex_lock(&icd->video_lock);
+
icf->icd = icd;
icd->use_count++;
@@ -304,7 +308,7 @@
}
}
- mutex_unlock(&video_lock);
+ mutex_unlock(&icd->video_lock);
file->private_data = icf;
dev_dbg(&icd->dev, "camera device open\n");
@@ -313,16 +317,16 @@
return 0;
- /* All errors are entered with the video_lock held */
+ /* First two errors are entered with the .video_lock held */
eiciadd:
soc_camera_free_user_formats(icd);
eiufmt:
icd->use_count--;
+ mutex_unlock(&icd->video_lock);
module_put(ici->ops->owner);
emgi:
module_put(icd->ops->owner);
emgd:
- mutex_unlock(&video_lock);
vfree(icf);
return ret;
}
@@ -334,15 +338,16 @@
struct soc_camera_host *ici = to_soc_camera_host(icd->dev.parent);
struct video_device *vdev = icd->vdev;
- mutex_lock(&video_lock);
+ mutex_lock(&icd->video_lock);
icd->use_count--;
if (!icd->use_count) {
ici->ops->remove(icd);
soc_camera_free_user_formats(icd);
}
+ mutex_unlock(&icd->video_lock);
+
module_put(icd->ops->owner);
module_put(ici->ops->owner);
- mutex_unlock(&video_lock);
vfree(icf);
@@ -424,18 +429,27 @@
if (ret < 0)
return ret;
+ mutex_lock(&icf->vb_vidq.vb_lock);
+
+ if (videobuf_queue_is_busy(&icf->vb_vidq)) {
+ dev_err(&icd->dev, "S_FMT denied: queue busy\n");
+ ret = -EBUSY;
+ goto unlock;
+ }
+
rect.left = icd->x_current;
rect.top = icd->y_current;
rect.width = pix->width;
rect.height = pix->height;
ret = ici->ops->set_fmt(icd, pix->pixelformat, &rect);
if (ret < 0) {
- return ret;
+ goto unlock;
} else if (!icd->current_fmt ||
icd->current_fmt->fourcc != pixfmt) {
dev_err(&ici->dev,
"Host driver hasn't set up current format correctly!\n");
- return -EINVAL;
+ ret = -EINVAL;
+ goto unlock;
}
icd->width = rect.width;
@@ -449,7 +463,12 @@
icd->width, icd->height);
/* set physical bus parameters */
- return ici->ops->set_bus_param(icd, pixfmt);
+ ret = ici->ops->set_bus_param(icd, pixfmt);
+
+unlock:
+ mutex_unlock(&icf->vb_vidq.vb_lock);
+
+ return ret;
}
static int soc_camera_enum_fmt_vid_cap(struct file *file, void *priv,
@@ -510,6 +529,7 @@
{
struct soc_camera_file *icf = file->private_data;
struct soc_camera_device *icd = icf->icd;
+ int ret;
WARN_ON(priv != file->private_data);
@@ -518,10 +538,16 @@
if (i != V4L2_BUF_TYPE_VIDEO_CAPTURE)
return -EINVAL;
+ mutex_lock(&icd->video_lock);
+
icd->ops->start_capture(icd);
/* This calls buf_queue from host driver's videobuf_queue_ops */
- return videobuf_streamon(&icf->vb_vidq);
+ ret = videobuf_streamon(&icf->vb_vidq);
+
+ mutex_unlock(&icd->video_lock);
+
+ return ret;
}
static int soc_camera_streamoff(struct file *file, void *priv,
@@ -537,12 +563,16 @@
if (i != V4L2_BUF_TYPE_VIDEO_CAPTURE)
return -EINVAL;
+ mutex_lock(&icd->video_lock);
+
/* This calls buf_release from host driver's videobuf_queue_ops for all
* remaining buffers. When the last buffer is freed, stop capture */
videobuf_streamoff(&icf->vb_vidq);
icd->ops->stop_capture(icd);
+ mutex_unlock(&icd->video_lock);
+
return 0;
}
@@ -654,6 +684,9 @@
if (a->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
return -EINVAL;
+ /* Cropping is allowed during a running capture, guard consistency */
+ mutex_lock(&icf->vb_vidq.vb_lock);
+
ret = ici->ops->set_fmt(icd, 0, &a->c);
if (!ret) {
icd->width = a->c.width;
@@ -662,6 +695,8 @@
icd->y_current = a->c.top;
}
+ mutex_unlock(&icf->vb_vidq.vb_lock);
+
return ret;
}
@@ -775,11 +810,32 @@
struct soc_camera_host *ici = to_soc_camera_host(icd->dev.parent);
int ret;
+ /*
+ * Possible race scenario:
+ * modprobe <camera-host-driver> triggers __func__
+ * at this moment respective <camera-sensor-driver> gets rmmod'ed
+ * to protect take module references.
+ */
+
+ if (!try_module_get(icd->ops->owner)) {
+ dev_err(&icd->dev, "Couldn't lock sensor driver.\n");
+ ret = -EINVAL;
+ goto emgd;
+ }
+
+ if (!try_module_get(ici->ops->owner)) {
+ dev_err(&icd->dev, "Couldn't lock capture bus driver.\n");
+ ret = -EINVAL;
+ goto emgi;
+ }
+
+ mutex_lock(&icd->video_lock);
+
/* We only call ->add() here to activate and probe the camera.
* We shall ->remove() and deactivate it immediately afterwards. */
ret = ici->ops->add(icd);
if (ret < 0)
- return ret;
+ goto eiadd;
ret = icd->ops->probe(icd);
if (ret >= 0) {
@@ -793,6 +849,12 @@
}
ici->ops->remove(icd);
+eiadd:
+ mutex_unlock(&icd->video_lock);
+ module_put(ici->ops->owner);
+emgi:
+ module_put(icd->ops->owner);
+emgd:
return ret;
}
@@ -966,6 +1028,7 @@
icd->dev.release = dummy_release;
icd->use_count = 0;
icd->host_priv = NULL;
+ mutex_init(&icd->video_lock);
return scan_add_device(icd);
}
@@ -1012,6 +1075,10 @@
#endif
};
+/*
+ * Usually called from the struct soc_camera_ops .probe() method, i.e., from
+ * soc_camera_probe() above with .video_lock held
+ */
int soc_camera_video_start(struct soc_camera_device *icd)
{
struct soc_camera_host *ici = to_soc_camera_host(icd->dev.parent);
@@ -1027,7 +1094,7 @@
dev_dbg(&ici->dev, "Allocated video_device %p\n", vdev);
strlcpy(vdev->name, ici->drv_name, sizeof(vdev->name));
- /* Maybe better &ici->dev */
+
vdev->parent = &icd->dev;
vdev->current_norm = V4L2_STD_UNKNOWN;
vdev->fops = &soc_camera_fops;
@@ -1061,10 +1128,10 @@
if (!icd->dev.parent || !vdev)
return;
- mutex_lock(&video_lock);
+ mutex_lock(&icd->video_lock);
video_unregister_device(vdev);
icd->vdev = NULL;
- mutex_unlock(&video_lock);
+ mutex_unlock(&icd->video_lock);
}
EXPORT_SYMBOL(soc_camera_video_stop);