drm/tegra: Fix error handling cleanup

The DRM driver's ->load() implementation didn't do a good job (no job at
all really) cleaning up on failure. Fix that by undoing any prior setup
when an error occurs. This requires a bit of rework to make it possible
to clean up fbdev midway.

This was tested by injecting errors at various points during the
initialization sequence and verifying that error cleanup didn't crash
and no memory leaked (using kmemleak).
Reported-by: Stéphane Marchesin <marcheu@chromium.org>
Reported-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/drm.c

@@ -42,13 +42,13 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
 
 	err = tegra_drm_fb_prepare(drm);
 	if (err < 0)
-		return err;
+		goto config;
 
 	drm_kms_helper_poll_init(drm);
 
 	err = host1x_device_init(device);
 	if (err < 0)
-		return err;
+		goto fbdev;
 
 	/*
 	 * We don't use the drm_irq_install() helpers provided by the DRM
@@ -59,13 +59,25 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
 
 	err = drm_vblank_init(drm, drm->mode_config.num_crtc);
 	if (err < 0)
-		return err;
+		goto device;
 
 	err = tegra_drm_fb_init(drm);
 	if (err < 0)
-		return err;
+		goto vblank;
 
 	return 0;
+
+vblank:
+	drm_vblank_cleanup(drm);
+device:
+	host1x_device_exit(device);
+fbdev:
+	drm_kms_helper_poll_fini(drm);
+	tegra_drm_fb_free(drm);
+config:
+	drm_mode_config_cleanup(drm);
+	kfree(tegra);
+	return err;
 }
 
 static int tegra_drm_unload(struct drm_device *drm)

drivers/gpu/drm/tegra/drm.h

@@ -288,6 +288,7 @@ bool tegra_fb_is_bottom_up(struct drm_framebuffer *framebuffer);
 int tegra_fb_get_tiling(struct drm_framebuffer *framebuffer,
 			struct tegra_bo_tiling *tiling);
 int tegra_drm_fb_prepare(struct drm_device *drm);
+void tegra_drm_fb_free(struct drm_device *drm);
 int tegra_drm_fb_init(struct drm_device *drm);
 void tegra_drm_fb_exit(struct drm_device *drm);
 #ifdef CONFIG_DRM_TEGRA_FBDEV

drivers/gpu/drm/tegra/fb.c

@@ -289,6 +289,11 @@ static struct tegra_fbdev *tegra_fbdev_create(struct drm_device *drm)
 	return fbdev;
 }
 
+static void tegra_fbdev_free(struct tegra_fbdev *fbdev)
+{
+	kfree(fbdev);
+}
+
 static int tegra_fbdev_init(struct tegra_fbdev *fbdev,
 			    unsigned int preferred_bpp,
 			    unsigned int num_crtc,
@@ -322,7 +327,7 @@ static int tegra_fbdev_init(struct tegra_fbdev *fbdev,
 	return err;
 }
 
-static void tegra_fbdev_free(struct tegra_fbdev *fbdev)
+static void tegra_fbdev_exit(struct tegra_fbdev *fbdev)
 {
 	struct fb_info *info = fbdev->base.fbdev;
 
@@ -345,7 +350,7 @@ static void tegra_fbdev_free(struct tegra_fbdev *fbdev)
 	}
 
 	drm_fb_helper_fini(&fbdev->base);
-	kfree(fbdev);
+	tegra_fbdev_free(fbdev);
 }
 
 void tegra_fbdev_restore_mode(struct tegra_fbdev *fbdev)
@@ -393,6 +398,15 @@ int tegra_drm_fb_prepare(struct drm_device *drm)
 	return 0;
 }
 
+void tegra_drm_fb_free(struct drm_device *drm)
+{
+#ifdef CONFIG_DRM_TEGRA_FBDEV
+	struct tegra_drm *tegra = drm->dev_private;
+
+	tegra_fbdev_free(tegra->fbdev);
+#endif
+}
+
 int tegra_drm_fb_init(struct drm_device *drm)
 {
 #ifdef CONFIG_DRM_TEGRA_FBDEV
@@ -413,6 +427,6 @@ void tegra_drm_fb_exit(struct drm_device *drm)
 #ifdef CONFIG_DRM_TEGRA_FBDEV
 	struct tegra_drm *tegra = drm->dev_private;
 
-	tegra_fbdev_free(tegra->fbdev);
+	tegra_fbdev_exit(tegra->fbdev);
 #endif
 }