[RFC 5/9] drm: introduce drm_dev_free() to fix error paths

[David Herrmann <dh.herrmann@gmail.com>]

The error paths in DRM bus drivers currently leak memory as they don't
correctly revert drm_dev_alloc(). Introduce drm_dev_free() to free DRM
devices which haven't been registered, yet.

We must be careful not to introduce any side-effects with cleanups done in
drm_dev_free(). drm_ht_remove(), drm_ctxbitmap_cleanup() and
drm_gem_destroy() are all fine in that regard.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
---
 drivers/gpu/drm/drm_pci.c      |  2 +-
 drivers/gpu/drm/drm_platform.c |  2 +-
 drivers/gpu/drm/drm_stub.c     | 35 +++++++++++++++++++++++++----------
 drivers/gpu/drm/drm_usb.c      |  2 +-
 include/drm/drmP.h             |  1 +
 5 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 0daee24..8ffc23d 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -356,7 +356,7 @@ int drm_get_pci_dev(struct pci_dev *pdev, const struct pci_device_id *ent,
 err_pci:
 	pci_disable_device(pdev);
 err_free:
-	kfree(dev);
+	drm_dev_free(dev);
 	return ret;
 }
 EXPORT_SYMBOL(drm_get_pci_dev);
diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
index 396713e..2b99ef0 100644
--- a/drivers/gpu/drm/drm_platform.c
+++ b/drivers/gpu/drm/drm_platform.c
@@ -64,7 +64,7 @@ int drm_get_platform_dev(struct platform_device *platdev,
 	return 0;
 
 err_free:
-	kfree(dev);
+	drm_dev_free(dev);
 	return ret;
 }
 EXPORT_SYMBOL(drm_get_platform_dev);
diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index f016ed8..8497dd1 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -374,7 +374,6 @@ static void drm_unplug_minor(struct drm_minor *minor)
  */
 void drm_put_dev(struct drm_device *dev)
 {
-	struct drm_driver *driver;
 	struct drm_map_list *r_list, *list_temp;
 
 	DRM_DEBUG("\n");
@@ -383,7 +382,6 @@ void drm_put_dev(struct drm_device *dev)
 		DRM_ERROR("cleanup called no dev\n");
 		return;
 	}
-	driver = dev->driver;
 
 	drm_lastclose(dev);
 
@@ -397,21 +395,15 @@ void drm_put_dev(struct drm_device *dev)
 
 	list_for_each_entry_safe(r_list, list_temp, &dev->maplist, head)
 		drm_rmmap(dev, r_list->map);
-	drm_ht_remove(&dev->map_hash);
-
-	drm_ctxbitmap_cleanup(dev);
 
 	if (drm_core_check_feature(dev, DRIVER_MODESET))
 		drm_put_minor(&dev->control);
 
-	if (driver->driver_features & DRIVER_GEM)
-		drm_gem_destroy(dev);
-
 	drm_put_minor(&dev->primary);
 
 	list_del(&dev->driver_item);
-	kfree(dev->devname);
-	kfree(dev);
+
+	drm_dev_free(dev);
 }
 EXPORT_SYMBOL(drm_put_dev);
 
@@ -508,6 +500,29 @@ err_free:
 EXPORT_SYMBOL(drm_dev_alloc);
 
 /**
+ * drm_dev_free - Free DRM device
+ * @dev: DRM device to free
+ *
+ * Free a DRM device that has previously been allocated via drm_dev_alloc().
+ * You must not use kfree() instead or you will leak memory.
+ *
+ * This must not be called once the device got registered. Use drm_put_dev()
+ * instead, which then calls drm_dev_free().
+ */
+void drm_dev_free(struct drm_device *dev)
+{
+	if (dev->driver->driver_features & DRIVER_GEM)
+		drm_gem_destroy(dev);
+
+	drm_ctxbitmap_cleanup(dev);
+	drm_ht_remove(&dev->map_hash);
+
+	kfree(dev->devname);
+	kfree(dev);
+}
+EXPORT_SYMBOL(drm_dev_free);
+
+/**
  * drm_dev_register - Register DRM device
  * @dev: Device to register
  *
diff --git a/drivers/gpu/drm/drm_usb.c b/drivers/gpu/drm/drm_usb.c
index 54d60f2..bace9d9 100644
--- a/drivers/gpu/drm/drm_usb.c
+++ b/drivers/gpu/drm/drm_usb.c
@@ -29,7 +29,7 @@ int drm_get_usb_dev(struct usb_interface *interface,
 	return 0;
 
 err_free:
-	kfree(dev);
+	drm_dev_free(dev);
 	return ret;
 
 }
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 30f83ee..d75f061 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1707,6 +1707,7 @@ static __inline__ void drm_core_dropmap(struct drm_local_map *map)
 
 struct drm_device *drm_dev_alloc(struct drm_driver *driver,
 				 struct device *parent);
+void drm_dev_free(struct drm_device *dev);
 int drm_dev_register(struct drm_device *dev);
 int drm_get_minor(struct drm_device *dev, struct drm_minor **minor, int type);
 /*@}*/
-- 
1.8.3.3