drm/panfrost: perfcnt: fix ref count leak in panfrost_perfcnt_enable_locked

in panfrost_perfcnt_enable_locked, pm_runtime_get_sync is called which
increments the counter even in case of failure, leading to incorrect
ref count. In case of failure, decrement the ref count before returning.
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200614063619.44944-1-navid.emamdoost@gmail.com

drivers/gpu/drm/panfrost/panfrost_perfcnt.c

@@ -83,11 +83,13 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 
 	ret = pm_runtime_get_sync(pfdev->dev);
 	if (ret < 0)
-		return ret;
+		goto err_put_pm;
 
 	bo = drm_gem_shmem_create(pfdev->ddev, perfcnt->bosize);
-	if (IS_ERR(bo))
-		return PTR_ERR(bo);
+	if (IS_ERR(bo)) {
+		ret = PTR_ERR(bo);
+		goto err_put_pm;
+	}
 
 	/* Map the perfcnt buf in the address space attached to file_priv. */
 	ret = panfrost_gem_open(&bo->base, file_priv);
@@ -168,6 +170,8 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 	panfrost_gem_close(&bo->base, file_priv);
 err_put_bo:
 	drm_gem_object_put(&bo->base);
+err_put_pm:
+	pm_runtime_put(pfdev->dev);
 	return ret;
 }