drm: Cleanup after failing to create master->unique and dev->name

v2: Userspace (notably xf86-video-{intel,ati}) became confused when
drmSetInterfaceVersion() started returning -EBUSY as they used a second
call (the first done in drmOpen()) to check their master credentials.
Since userspace wants to be able to repeatedly call
drmSetInterfaceVersion() allow them to do so.

v3: Rebase to drm-core-next.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_ioctl.c

@@ -64,6 +64,19 @@ int drm_getunique(struct drm_device *dev, void *data,
 	return 0;
 }
 
+static void
+drm_unset_busid(struct drm_device *dev,
+		struct drm_master *master)
+{
+	kfree(dev->devname);
+	dev->devname = NULL;
+
+	kfree(master->unique);
+	master->unique = NULL;
+	master->unique_len = 0;
+	master->unique_size = 0;
+}
+
 /**
  * Set the bus id.
  *
@@ -94,17 +107,24 @@ int drm_setunique(struct drm_device *dev, void *data,
 	master->unique_len = u->unique_len;
 	master->unique_size = u->unique_len + 1;
 	master->unique = kmalloc(master->unique_size, GFP_KERNEL);
-	if (!master->unique)
-		return -ENOMEM;
-	if (copy_from_user(master->unique, u->unique, master->unique_len))
-		return -EFAULT;
+	if (!master->unique) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	if (copy_from_user(master->unique, u->unique, master->unique_len)) {
+		ret = -EFAULT;
+		goto err;
+	}
 
 	master->unique[master->unique_len] = '\0';
 
 	dev->devname = kmalloc(strlen(dev->driver->pci_driver.name) +
 			       strlen(master->unique) + 2, GFP_KERNEL);
-	if (!dev->devname)
-		return -ENOMEM;
+	if (!dev->devname) {
+		ret = -ENOMEM;
+		goto err;
+	}
 
 	sprintf(dev->devname, "%s@%s", dev->driver->pci_driver.name,
 		master->unique);
@@ -113,24 +133,36 @@ int drm_setunique(struct drm_device *dev, void *data,
 	 * busid.
 	 */
 	ret = sscanf(master->unique, "PCI:%d:%d:%d", &bus, &slot, &func);
-	if (ret != 3)
-		return -EINVAL;
+	if (ret != 3) {
+		ret = -EINVAL;
+		goto err;
+	}
+
 	domain = bus >> 8;
 	bus &= 0xff;
 
 	if ((domain != drm_get_pci_domain(dev)) ||
 	    (bus != dev->pdev->bus->number) ||
 	    (slot != PCI_SLOT(dev->pdev->devfn)) ||
-	    (func != PCI_FUNC(dev->pdev->devfn)))
-		return -EINVAL;
+	    (func != PCI_FUNC(dev->pdev->devfn))) {
+		ret = -EINVAL;
+		goto err;
+	}
 
 	return 0;
+
+err:
+	drm_unset_busid(dev, master);
+	return ret;
 }
 
 static int drm_set_busid(struct drm_device *dev, struct drm_file *file_priv)
 {
 	struct drm_master *master = file_priv->master;
-	int len;
+	int len, ret;
+
+	if (master->unique != NULL)
+		drm_unset_busid(dev, master);
 
 	if (drm_core_check_feature(dev, DRIVER_USE_PLATFORM_DEVICE)) {
 		master->unique_len = 10 + strlen(dev->platformdev->name);
@@ -142,15 +174,20 @@ static int drm_set_busid(struct drm_device *dev, struct drm_file *file_priv)
 		len = snprintf(master->unique, master->unique_len,
 			"platform:%s", dev->platformdev->name);
 
-		if (len > master->unique_len)
+		if (len > master->unique_len) {
 			DRM_ERROR("Unique buffer overflowed\n");
+			ret = -EINVAL;
+			goto err;
+		}
 
 		dev->devname =
 			kmalloc(strlen(dev->platformdev->name) +
 				master->unique_len + 2, GFP_KERNEL);
 
-		if (dev->devname == NULL)
-			return -ENOMEM;
+		if (dev->devname == NULL) {
+			ret = -ENOMEM;
+			goto err;
+		}
 
 		sprintf(dev->devname, "%s@%s", dev->platformdev->name,
 			master->unique);
@@ -168,23 +205,31 @@ static int drm_set_busid(struct drm_device *dev, struct drm_file *file_priv)
 			dev->pdev->bus->number,
 			PCI_SLOT(dev->pdev->devfn),
 			PCI_FUNC(dev->pdev->devfn));
-		if (len >= master->unique_len)
+		if (len >= master->unique_len) {
 			DRM_ERROR("buffer overflow");
-		else
+			ret = -EINVAL;
+			goto err;
+		} else
 			master->unique_len = len;
 
 		dev->devname =
 			kmalloc(strlen(dev->driver->pci_driver.name) +
 				master->unique_len + 2, GFP_KERNEL);
 
-		if (dev->devname == NULL)
-			return -ENOMEM;
+		if (dev->devname == NULL) {
+			ret = -ENOMEM;
+			goto err;
+		}
 
 		sprintf(dev->devname, "%s@%s", dev->driver->pci_driver.name,
 			master->unique);
 	}
 
 	return 0;
+
+err:
+	drm_unset_busid(dev, master);
+	return ret;
 }
 
 /**
@@ -348,7 +393,9 @@ int drm_setversion(struct drm_device *dev, void *data, struct drm_file *file_pri
 			/*
 			 * Version 1.1 includes tying of DRM to specific device
 			 */
-			drm_set_busid(dev, file_priv);
+			retcode = drm_set_busid(dev, file_priv);
+			if (retcode)
+				goto done;
 		}
 	}