From: Thierry Reding <treding@nvidia.com>
Date: Wed, 8 Nov 2017 13:20:01 +0100
Subject: drm/tegra: sor: Register debugfs in ->late_register()
Git-commit: 5b8e043b6df4caf4aa41921ed584659a0c5ad269
Patch-mainline: v4.16-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

The ->late_register() and ->early_unregister() callbacks are called at
the right time to make sure userspace only accesses interfaces when it
should. Move debugfs registration and unregistration to these callback
functions to avoid potential races with userspace.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/tegra/sor.c |   53 +++++++++++++++-----------------------------
 1 file changed, 19 insertions(+), 34 deletions(-)

--- a/drivers/gpu/drm/tegra/sor.c
+++ b/drivers/gpu/drm/tegra/sor.c
@@ -183,7 +183,6 @@ struct tegra_sor {
 	struct drm_dp_aux *aux;
 
 	struct drm_info_list *debugfs_files;
-	struct drm_minor *minor;
 
 	const struct tegra_sor_ops *ops;
 
@@ -1256,53 +1255,46 @@ static const struct drm_info_list debugf
 	{ "regs", tegra_sor_show_regs, 0, NULL },
 };
 
-static int tegra_sor_debugfs_init(struct tegra_sor *sor,
-				  struct drm_minor *minor)
+static int tegra_sor_late_register(struct drm_connector *connector)
 {
-	struct dentry *root = sor->output.connector.debugfs_entry;
-	unsigned int i;
+	struct tegra_output *output = connector_to_output(connector);
+	unsigned int i, count = ARRAY_SIZE(debugfs_files);
+	struct drm_minor *minor = connector->dev->primary;
+	struct dentry *root = connector->debugfs_entry;
+	struct tegra_sor *sor = to_sor(output);
 	int err;
 
 	sor->debugfs_files = kmemdup(debugfs_files, sizeof(debugfs_files),
 				     GFP_KERNEL);
-	if (!sor->debugfs_files) {
-		err = -ENOMEM;
-		goto remove;
-	}
+	if (!sor->debugfs_files)
+		return -ENOMEM;
 
-	for (i = 0; i < ARRAY_SIZE(debugfs_files); i++)
+	for (i = 0; i < count; i++)
 		sor->debugfs_files[i].data = sor;
 
-	err = drm_debugfs_create_files(sor->debugfs_files,
-				       ARRAY_SIZE(debugfs_files),
-				       root, minor);
+	err = drm_debugfs_create_files(sor->debugfs_files, count, root, minor);
 	if (err < 0)
 		goto free;
 
-	sor->minor = minor;
-
 	return 0;
 
 free:
 	kfree(sor->debugfs_files);
 	sor->debugfs_files = NULL;
-remove:
-	debugfs_remove_recursive(root);
+
 	return err;
 }
 
-static void tegra_sor_debugfs_exit(struct tegra_sor *sor)
+static void tegra_sor_early_unregister(struct drm_connector *connector)
 {
-	struct dentry *root = sor->output.connector.debugfs_entry;
-
-	drm_debugfs_remove_files(sor->debugfs_files, ARRAY_SIZE(debugfs_files),
-				 sor->minor);
-	sor->minor = NULL;
+	struct tegra_output *output = connector_to_output(connector);
+	unsigned int count = ARRAY_SIZE(debugfs_files);
+	struct tegra_sor *sor = to_sor(output);
 
+	drm_debugfs_remove_files(sor->debugfs_files, count,
+				 connector->dev->primary);
 	kfree(sor->debugfs_files);
 	sor->debugfs_files = NULL;
-
-	debugfs_remove_recursive(root);
 }
 
 static void tegra_sor_connector_reset(struct drm_connector *connector)
@@ -1355,6 +1347,8 @@ static const struct drm_connector_funcs
 	.destroy = tegra_output_connector_destroy,
 	.atomic_duplicate_state = tegra_sor_connector_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+	.late_register = tegra_sor_late_register,
+	.early_unregister = tegra_sor_early_unregister,
 };
 
 static int tegra_sor_connector_get_modes(struct drm_connector *connector)
@@ -2347,12 +2341,6 @@ static int tegra_sor_init(struct host1x_
 
 	sor->output.encoder.possible_crtcs = 0x3;
 
-	if (IS_ENABLED(CONFIG_DEBUG_FS)) {
-		err = tegra_sor_debugfs_init(sor, drm->primary);
-		if (err < 0)
-			dev_err(sor->dev, "debugfs setup failed: %d\n", err);
-	}
-
 	if (sor->aux) {
 		err = drm_dp_aux_attach(sor->aux, &sor->output);
 		if (err < 0) {
@@ -2421,9 +2409,6 @@ static int tegra_sor_exit(struct host1x_
 	clk_disable_unprepare(sor->clk_dp);
 	clk_disable_unprepare(sor->clk);
 
-	if (IS_ENABLED(CONFIG_DEBUG_FS))
-		tegra_sor_debugfs_exit(sor);
-
 	return 0;
 }