When the sub-device is registered, increment the use count of the sub-device
owner only if it's different from the owner of the driver for the media
device. This avoids increasing the use count by the module itself and thus
making it possible to unload it when it's not in use.
Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
Changes since v1:
- Check that v4l2_dev->dev and v4l2_dev->dev->driver are non-NULL before
using them.
- Store the information on the same owner into struct v4l2_subdev. This avoids
issues related to unregistering subdevs through v4l2_device_unregister().
drivers/media/v4l2-core/v4l2-device.c | 18 +++++++++++++++---
include/media/v4l2-subdev.h | 1 +
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c
index 02d1b63..015f92a 100644
--- a/drivers/media/v4l2-core/v4l2-device.c
+++ b/drivers/media/v4l2-core/v4l2-device.c
@@ -158,7 +158,17 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
/* Warn if we apparently re-register a subdev */
WARN_ON(sd->v4l2_dev != NULL);
- if (!try_module_get(sd->owner))
+ /*
+ * The reason to acquire the module here is to avoid unloading
+ * a module of sub-device which is registered to a media
+ * device. To make it possible to unload modules for media
+ * devices that also register sub-devices, do not
+ * try_module_get() such sub-device owners.
+ */
+ sd->owner_v4l2_dev = v4l2_dev->dev && v4l2_dev->dev->driver &&
+ sd->owner == v4l2_dev->dev->driver->owner;
+
+ if (!sd->owner_v4l2_dev && !try_module_get(sd->owner))
return -ENODEV;
sd->v4l2_dev = v4l2_dev;
@@ -192,7 +202,8 @@ error_unregister:
if (sd->internal_ops && sd->internal_ops->unregistered)
sd->internal_ops->unregistered(sd);
error_module:
- module_put(sd->owner);
+ if (!sd->owner_v4l2_dev)
+ module_put(sd->owner);
sd->v4l2_dev = NULL;
return err;
}
@@ -280,6 +291,7 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
}
#endif
video_unregister_device(sd->devnode);
- module_put(sd->owner);
+ if (!sd->owner_v4l2_dev)
+ module_put(sd->owner);
}
EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index d67210a..6d03b54 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -579,6 +579,7 @@ struct v4l2_subdev {
#endif
struct list_head list;
struct module *owner;
+ bool owner_v4l2_dev;
u32 flags;
struct v4l2_device *v4l2_dev;
const struct v4l2_subdev_ops *ops;
--
1.8.3.2
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
