From: Thierry Reding <treding@nvidia.com>
Date: Wed, 8 Nov 2017 13:12:44 +0100
Subject: drm/tegra: dsi: Register debugfs in ->late_register()
Git-commit: a813d70425061ad59bc8f980ae822f4fc35c9250
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/dsi.c |   58 +++++++++++++-------------------------------
 1 file changed, 18 insertions(+), 40 deletions(-)

--- a/drivers/gpu/drm/tegra/dsi.c
+++ b/drivers/gpu/drm/tegra/dsi.c
@@ -65,8 +65,6 @@ struct tegra_dsi {
 	struct clk *clk;
 
 	struct drm_info_list *debugfs_files;
-	struct drm_minor *minor;
-	struct dentry *debugfs;
 
 	unsigned long flags;
 	enum mipi_dsi_pixel_format format;
@@ -230,58 +228,46 @@ static struct drm_info_list debugfs_file
 	{ "regs", tegra_dsi_show_regs, 0, NULL },
 };
 
-static int tegra_dsi_debugfs_init(struct tegra_dsi *dsi,
-				  struct drm_minor *minor)
+static int tegra_dsi_late_register(struct drm_connector *connector)
 {
-	const char *name = dev_name(dsi->dev);
-	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_dsi *dsi = to_dsi(output);
 	int err;
 
-	dsi->debugfs = debugfs_create_dir(name, minor->debugfs_root);
-	if (!dsi->debugfs)
-		return -ENOMEM;
-
 	dsi->debugfs_files = kmemdup(debugfs_files, sizeof(debugfs_files),
 				     GFP_KERNEL);
-	if (!dsi->debugfs_files) {
-		err = -ENOMEM;
-		goto remove;
-	}
+	if (!dsi->debugfs_files)
+		return -ENOMEM;
 
-	for (i = 0; i < ARRAY_SIZE(debugfs_files); i++)
+	for (i = 0; i < count; i++)
 		dsi->debugfs_files[i].data = dsi;
 
-	err = drm_debugfs_create_files(dsi->debugfs_files,
-				       ARRAY_SIZE(debugfs_files),
-				       dsi->debugfs, minor);
+	err = drm_debugfs_create_files(dsi->debugfs_files, count, root, minor);
 	if (err < 0)
 		goto free;
 
-	dsi->minor = minor;
-
 	return 0;
 
 free:
 	kfree(dsi->debugfs_files);
 	dsi->debugfs_files = NULL;
-remove:
-	debugfs_remove(dsi->debugfs);
-	dsi->debugfs = NULL;
 
 	return err;
 }
 
-static void tegra_dsi_debugfs_exit(struct tegra_dsi *dsi)
+static void tegra_dsi_early_unregister(struct drm_connector *connector)
 {
-	drm_debugfs_remove_files(dsi->debugfs_files, ARRAY_SIZE(debugfs_files),
-				 dsi->minor);
-	dsi->minor = NULL;
+	struct tegra_output *output = connector_to_output(connector);
+	unsigned int count = ARRAY_SIZE(debugfs_files);
+	struct tegra_dsi *dsi = to_dsi(output);
 
+	drm_debugfs_remove_files(dsi->debugfs_files, count,
+				 connector->dev->primary);
 	kfree(dsi->debugfs_files);
 	dsi->debugfs_files = NULL;
-
-	debugfs_remove(dsi->debugfs);
-	dsi->debugfs = NULL;
 }
 
 #define PKT_ID0(id)	((((id) & 0x3f) <<  3) | (1 <<  9))
@@ -823,6 +809,8 @@ static const struct drm_connector_funcs
 	.destroy = tegra_output_connector_destroy,
 	.atomic_duplicate_state = tegra_dsi_connector_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+	.late_register = tegra_dsi_late_register,
+	.early_unregister = tegra_dsi_early_unregister,
 };
 
 static enum drm_mode_status
@@ -1076,12 +1064,6 @@ static int tegra_dsi_init(struct host1x_
 		dsi->output.encoder.possible_crtcs = 0x3;
 	}
 
-	if (IS_ENABLED(CONFIG_DEBUG_FS)) {
-		err = tegra_dsi_debugfs_init(dsi, drm->primary);
-		if (err < 0)
-			dev_err(dsi->dev, "debugfs setup failed: %d\n", err);
-	}
-
 	return 0;
 }
 
@@ -1090,10 +1072,6 @@ static int tegra_dsi_exit(struct host1x_
 	struct tegra_dsi *dsi = host1x_client_to_dsi(client);
 
 	tegra_output_exit(&dsi->output);
-
-	if (IS_ENABLED(CONFIG_DEBUG_FS))
-		tegra_dsi_debugfs_exit(dsi);
-
 	regulator_disable(dsi->vdd);
 
 	return 0;