1 files changed, 56 insertions, 11 deletions

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 53d09a19f7e1..9362609df38a 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -37,11 +37,9 @@
 #include "drm_legacy.h"
 #include "drm_internal.h"
 
-unsigned int drm_debug = 0;	/* 1 to enable debug output */
+unsigned int drm_debug = 0;	/* bitmask of DRM_UT_x */
 EXPORT_SYMBOL(drm_debug);
 
-bool drm_atomic = 0;
-
 MODULE_AUTHOR(CORE_AUTHOR);
 MODULE_DESCRIPTION(CORE_DESC);
 MODULE_LICENSE("GPL and additional rights");
@@ -55,7 +53,6 @@ module_param_named(debug, drm_debug, int, 0600);
 static DEFINE_SPINLOCK(drm_minor_lock);
 static struct idr drm_minors_idr;
 
-struct class *drm_class;
 static struct dentry *drm_debugfs_root;
 
 void drm_err(const char *format, ...)
@@ -398,15 +395,51 @@ void drm_minor_release(struct drm_minor *minor)
 }
 
 /**
+ * DOC: driver instance overview
+ *
+ * A device instance for a drm driver is represented by struct &drm_device. This
+ * is allocated with drm_dev_alloc(), usually from bus-specific ->probe()
+ * callbacks implemented by the driver. The driver then needs to initialize all
+ * the various subsystems for the drm device like memory management, vblank
+ * handling, modesetting support and intial output configuration plus obviously
+ * initialize all the corresponding hardware bits. An important part of this is
+ * also calling drm_dev_set_unique() to set the userspace-visible unique name of
+ * this device instance. Finally when everything is up and running and ready for
+ * userspace the device instance can be published using drm_dev_register().
+ *
+ * There is also deprecated support for initalizing device instances using
+ * bus-specific helpers and the ->load() callback. But due to
+ * backwards-compatibility needs the device instance have to be published too
+ * early, which requires unpretty global locking to make safe and is therefore
+ * only support for existing drivers not yet converted to the new scheme.
+ *
+ * When cleaning up a device instance everything needs to be done in reverse:
+ * First unpublish the device instance with drm_dev_unregister(). Then clean up
+ * any other resources allocated at device initialization and drop the driver's
+ * reference to &drm_device using drm_dev_unref().
+ *
+ * Note that the lifetime rules for &drm_device instance has still a lot of
+ * historical baggage. Hence use the reference counting provided by
+ * drm_dev_ref() and drm_dev_unref() only carefully.
+ *
+ * Also note that embedding of &drm_device is currently not (yet) supported (but
+ * it would be easy to add). Drivers can store driver-private data in the
+ * dev_priv field of &drm_device.
+ */
+
+/**
  * drm_put_dev - Unregister and release a DRM device
  * @dev: DRM device
  *
  * Called at module unload time or when a PCI device is unplugged.
  *
- * Use of this function is discouraged. It will eventually go away completely.
- * Please use drm_dev_unregister() and drm_dev_unref() explicitly instead.
- *
  * Cleans up all DRM device, calling drm_lastclose().
+ *
+ * Note: Use of this function is deprecated. It will eventually go away
+ * completely.  Please use drm_dev_unregister() and drm_dev_unref() explicitly
+ * instead to make sure that the device isn't userspace accessible any more
+ * while teardown is in progress, ensuring that userspace can't access an
+ * inconsistent state.
  */
 void drm_put_dev(struct drm_device *dev)
 {
@@ -519,7 +552,9 @@ static void drm_fs_inode_free(struct inode *inode)
  *
  * Allocate and initialize a new DRM device. No device registration is done.
  * Call drm_dev_register() to advertice the device to user space and register it
- * with other core subsystems.
+ * with other core subsystems. This should be done last in the device
+ * initialization sequence to make sure userspace can't access an inconsistent
+ * state.
  *
  * The initial ref-count of the object is 1. Use drm_dev_ref() and
  * drm_dev_unref() to take and drop further ref-counts.
@@ -566,6 +601,8 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver,
 		ret = drm_minor_alloc(dev, DRM_MINOR_CONTROL);
 		if (ret)
 			goto err_minors;
+
+		WARN_ON(driver->suspend || driver->resume);
 	}
 
 	if (drm_core_check_feature(dev, DRIVER_RENDER)) {
@@ -672,6 +709,12 @@ EXPORT_SYMBOL(drm_dev_unref);
  *
  * Never call this twice on any device!
  *
+ * NOTE: To ensure backward compatibility with existing drivers method this
+ * function calls the ->load() method after registering the device nodes,
+ * creating race conditions. Usage of the ->load() methods is therefore
+ * deprecated, drivers must perform all initialization before calling
+ * drm_dev_register().
+ *
  * RETURNS:
  * 0 on success, negative error code on failure.
  */
@@ -719,6 +762,9 @@ EXPORT_SYMBOL(drm_dev_register);
  * Unregister the DRM device from the system. This does the reverse of
  * drm_dev_register() but does not deallocate the device. The caller must call
  * drm_dev_unref() to drop their final reference.
+ *
+ * This should be called first in the device teardown code to make sure
+ * userspace can't access the device instance any more.
  */
 void drm_dev_unregister(struct drm_device *dev)
 {
@@ -839,10 +885,9 @@ static int __init drm_core_init(void)
 	if (register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops))
 		goto err_p1;
 
-	drm_class = drm_sysfs_create(THIS_MODULE, "drm");
-	if (IS_ERR(drm_class)) {
+	ret = drm_sysfs_init();
+	if (ret < 0) {
 		printk(KERN_ERR "DRM: Error creating drm class.\n");
-		ret = PTR_ERR(drm_class);
 		goto err_p2;
 	}