drm/arm/malidp: use drmm_* to allocate driver structures

Use drm managed resources to allocate driver structures and get rid of
the deprecated drm_dev_alloc() call and replace it with
devm_drm_dev_alloc().

This also serves as preparation to get rid of drm_device->dev_private
and to fix use-after-free issues on driver unload.
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026155934.125294-2-dakr@redhat.com

drivers/gpu/drm/arm/malidp_drv.c

@@ -23,6 +23,7 @@
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_dma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_managed.h>
 #include <drm/drm_modeset_helper.h>
 #include <drm/drm_module.h>
 #include <drm/drm_of.h>
@@ -716,11 +717,13 @@ static int malidp_bind(struct device *dev)
 	int ret = 0, i;
 	u32 version, out_depth = 0;
 
-	malidp = devm_kzalloc(dev, sizeof(*malidp), GFP_KERNEL);
-	if (!malidp)
-		return -ENOMEM;
+	malidp = devm_drm_dev_alloc(dev, &malidp_driver, typeof(*malidp), base);
+	if (IS_ERR(malidp))
+		return PTR_ERR(malidp);
+
+	drm = &malidp->base;
 
-	hwdev = devm_kzalloc(dev, sizeof(*hwdev), GFP_KERNEL);
+	hwdev = drmm_kzalloc(drm, sizeof(*hwdev), GFP_KERNEL);
 	if (!hwdev)
 		return -ENOMEM;
 
@@ -753,12 +756,6 @@ static int malidp_bind(struct device *dev)
 	if (ret && ret != -ENODEV)
 		return ret;
 
-	drm = drm_dev_alloc(&malidp_driver, dev);
-	if (IS_ERR(drm)) {
-		ret = PTR_ERR(drm);
-		goto alloc_fail;
-	}
-
 	drm->dev_private = malidp;
 	dev_set_drvdata(dev, drm);
 
@@ -887,8 +884,6 @@ static int malidp_bind(struct device *dev)
 		malidp_runtime_pm_suspend(dev);
 	drm->dev_private = NULL;
 	dev_set_drvdata(dev, NULL);
-	drm_dev_put(drm);
-alloc_fail:
 	of_reserved_mem_device_release(dev);
 
 	return ret;
@@ -917,7 +912,6 @@ static void malidp_unbind(struct device *dev)
 		malidp_runtime_pm_suspend(dev);
 	drm->dev_private = NULL;
 	dev_set_drvdata(dev, NULL);
-	drm_dev_put(drm);
 	of_reserved_mem_device_release(dev);
 }
 

drivers/gpu/drm/arm/malidp_drv.h

@@ -29,6 +29,7 @@ struct malidp_error_stats {
 };
 
 struct malidp_drm {
+	struct drm_device base;
 	struct malidp_hw_device *dev;
 	struct drm_crtc crtc;
 	struct drm_writeback_connector mw_connector;