[PATCH 26/51] drm: Manage drm_mode_config_init with drmm_

[Daniel Vetter <daniel.vetter@ffwll.ch>]

drm_mode_config_cleanup is idempotent, so no harm in calling this
twice. This allows us to gradually switch drivers over by removing
explicit drm_mode_config_cleanup calls.

With this step it's now also possible that (at least for simple
drivers) automatic resource cleanup can be done correctly without a
drm_driver->release hook. Therefore allow this now in
devm_drm_dev_init().

Also with drmm_ explicit drm_driver->release hooks are kinda not the
best option: Drivers can always just register their current release
hook with drmm_add_action, but even better they could split them up to
simplify the unwinding for the driver load failure case. So deprecate
that hook to discourage future users.

v2: Fixup the example in the kerneldoc too.

v3:
- For paranoia, double check that minor->dev == dev in the release
  hook, because I botched the pointer math in the drmm library.
- Call drm_mode_config_cleanup when drmm_add_action fails, we'd be
  missing some mutex_destroy and ida_cleanup otherwise (Laurent)

v4: Add a drmm_add_action_or_reset (like devm_ has) to encapsulate this
pattern (Noralf).

v5: Fix oversight in the new drmm_add_action_or_reset macro (Noralf)

v4: Review from Sam:
- drmm_mode_config_init wrapper (also suggested by Thomas)
- improve commit message, explain better why ->relase is deprecated

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/gpu/drm/drm_drv.c         | 23 +++++++----------------
 drivers/gpu/drm/drm_managed.c     | 14 ++++++++++++++
 drivers/gpu/drm/drm_mode_config.c | 13 ++++++++++++-
 include/drm/drm_managed.h         |  7 +++++++
 include/drm/drm_mode_config.h     | 19 ++++++++++++++++++-
 5 files changed, 58 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index c709a0ce018c..a82702d0c2fb 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -98,6 +98,8 @@ static void drm_minor_alloc_release(struct drm_device *dev, void *data)
 	struct drm_minor *minor = data;
 	unsigned long flags;
 
+	WARN_ON(dev != minor->dev);
+
 	put_device(minor->kdev);
 
 	spin_lock_irqsave(&drm_minor_lock, flags);
@@ -267,8 +269,7 @@ void drm_minor_release(struct drm_minor *minor)
  *
  * The following example shows a typical structure of a DRM display driver.
  * The example focus on the probe() function and the other functions that is
- * almost always present and serves as a demonstration of devm_drm_dev_init()
- * usage with its accompanying drm_driver->release callback.
+ * almost always present and serves as a demonstration of devm_drm_dev_init().
  *
  * .. code-block:: c
  *
@@ -278,16 +279,8 @@ void drm_minor_release(struct drm_minor *minor)
  *		struct clk *pclk;
  *	};
  *
- *	static void driver_drm_release(struct drm_device *drm)
- *	{
- *		struct driver_device *priv = container_of(...);
- *
- *		drm_mode_config_cleanup(drm);
- *	}
- *
  *	static struct drm_driver driver_drm_driver = {
  *		[...]
- *		.release = driver_drm_release,
  *	};
  *
  *	static int driver_probe(struct platform_device *pdev)
@@ -312,7 +305,9 @@ void drm_minor_release(struct drm_minor *minor)
  *		}
  *		drmm_add_final_kfree(drm, priv);
  *
- *		drm_mode_config_init(drm);
+ *		ret = drm_mode_config_init(drm);
+ *		if (ret)
+ *			return ret;
  *
  *		priv->userspace_facing = drmm_kzalloc(..., GFP_KERNEL);
  *		if (!priv->userspace_facing)
@@ -710,8 +705,7 @@ static void devm_drm_dev_init_release(void *data)
  * @driver: DRM driver
  *
  * Managed drm_dev_init(). The DRM device initialized with this function is
- * automatically put on driver detach using drm_dev_put(). You must supply a
- * &drm_driver.release callback to control the finalization explicitly.
+ * automatically put on driver detach using drm_dev_put().
  *
  * RETURNS:
  * 0 on success, or error code on failure.
@@ -722,9 +716,6 @@ int devm_drm_dev_init(struct device *parent,
 {
 	int ret;
 
-	if (WARN_ON(!driver->release))
-		return -EINVAL;
-
 	ret = drm_dev_init(dev, driver, parent);
 	if (ret)
 		return ret;
diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c
index 0883615c2088..8c5f1f03c485 100644
--- a/drivers/gpu/drm/drm_managed.c
+++ b/drivers/gpu/drm/drm_managed.c
@@ -142,6 +142,20 @@ int __drmm_add_action(struct drm_device *dev,
 }
 EXPORT_SYMBOL(__drmm_add_action);
 
+int __drmm_add_action_or_reset(struct drm_device *dev,
+			       drmres_release_t action,
+			       void *data, const char *name)
+{
+	int ret;
+
+	ret = __drmm_add_action(dev, action, data, name);
+	if (ret)
+		action(dev, data);
+
+	return ret;
+}
+EXPORT_SYMBOL(__drmm_add_action_or_reset);
+
 void drmm_remove_action(struct drm_device *dev,
 			drmres_release_t action,
 			void *data)
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 08e6eff6a179..6f7005bc597f 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -25,6 +25,7 @@
 #include <drm/drm_drv.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_file.h>
+#include <drm/drm_managed.h>
 #include <drm/drm_mode_config.h>
 #include <drm/drm_print.h>
 #include <linux/dma-resv.h>
@@ -373,6 +374,11 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
 	return 0;
 }
 
+static void drm_mode_config_init_release(struct drm_device *dev, void *ptr)
+{
+	drm_mode_config_cleanup(dev);
+}
+
 /**
  * drm_mode_config_init - initialize DRM mode_configuration structure
  * @dev: DRM device
@@ -384,8 +390,10 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
  * problem, since this should happen single threaded at init time. It is the
  * driver's problem to ensure this guarantee.
  *
+ * Cleanup is automatically handled through registering drm_mode_config_cleanup
+ * with drmm_add_action().
  */
-void drm_mode_config_init(struct drm_device *dev)
+int drm_mode_config_init(struct drm_device *dev)
 {
 	mutex_init(&dev->mode_config.mutex);
 	drm_modeset_lock_init(&dev->mode_config.connection_mutex);
@@ -443,6 +451,9 @@ void drm_mode_config_init(struct drm_device *dev)
 		drm_modeset_acquire_fini(&modeset_ctx);
 		dma_resv_fini(&resv);
 	}
+
+	return drmm_add_action_or_reset(dev, drm_mode_config_init_release,
+					NULL);
 }
 EXPORT_SYMBOL(drm_mode_config_init);
 
diff --git a/include/drm/drm_managed.h b/include/drm/drm_managed.h
index 2b1ba2ad5582..1e6291407586 100644
--- a/include/drm/drm_managed.h
+++ b/include/drm/drm_managed.h
@@ -18,6 +18,13 @@ int __must_check __drmm_add_action(struct drm_device *dev,
 				   drmres_release_t action,
 				   void *data, const char *name);
 
+#define drmm_add_action_or_reset(dev, action, data) \
+	__drmm_add_action_or_reset(dev, action, data, #action)
+
+int __must_check __drmm_add_action_or_reset(struct drm_device *dev,
+					    drmres_release_t action,
+					    void *data, const char *name);
+
 void drmm_remove_action(struct drm_device *dev,
 			drmres_release_t action,
 			void *data);
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index 3bcbe30339f0..aa6288bf04df 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -929,7 +929,24 @@ struct drm_mode_config {
 	const struct drm_mode_config_helper_funcs *helper_private;
 };
 
-void drm_mode_config_init(struct drm_device *dev);
+int drm_mode_config_init(struct drm_device *dev);
+
+/**
+ * drmm_mode_config_init - managed DRM mode_configuration structure
+ * 	initialization
+ * @dev: DRM device
+ *
+ * This is a managed version of drm_mode_config_init(). The only difference is
+ * that this version is annotated with __must_check, to make sure that drivers
+ * can actually rely on the automatic cleanup.
+ *
+ * Returns: 0 on success, negative error value on failure.
+ */
+static inline __must_check int drmm_mode_config_init(struct drm_device *dev)
+{
+	return drm_mode_config_init(dev);
+}
+
 void drm_mode_config_reset(struct drm_device *dev);
 void drm_mode_config_cleanup(struct drm_device *dev);
 
-- 
2.24.1

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