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Commit b0d12325 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm: refcounting for crtc framebuffers 



With the prep patch to encapsulate ->set_crtc calls, this is now
rather easy. Hooray for inconsistent semantics between ->set_crtc and
->page_flip, where the driver callback is supposed to update the fb
pointer, and ->update_plane, where the drm core does the same.

Also, since the drm core functions check crtc->fb before calling into
driver callbacks, we can't really reduce the critical sections
protected by the mode_config locks.

Reviewed-by: default avatarRob Clark <rob@ti.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 6c2a7532

drivers/gpu/drm/drm_crtc.c

+30 −7
Original line number Diff line number Diff line
@@ -1984,8 +1984,21 @@ out: 
int drm_mode_set_config_internal(struct drm_mode_set *set)

{

	struct drm_crtc *crtc = set->crtc;

	struct drm_framebuffer *fb, *old_fb;

	int ret;



	old_fb = crtc->fb;

	fb = set->fb;



	ret = crtc->funcs->set_config(set);

	if (ret == 0) {

		if (old_fb)

			drm_framebuffer_unreference(old_fb);

		if (fb)

			drm_framebuffer_reference(fb);

	}



	return crtc->funcs->set_config(set);

	return ret;

}

EXPORT_SYMBOL(drm_mode_set_config_internal);
@@ -2046,6 +2059,8 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, 
				goto out;

			}

			fb = crtc->fb;

			/* Make refcounting symmetric with the lookup path. */

			drm_framebuffer_reference(fb);

		} else {

			fb = drm_framebuffer_lookup(dev, crtc_req->fb_id);

			if (!fb) {
@@ -2054,9 +2069,6 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, 
				ret = -EINVAL;

				goto out;

			}

			/* fb is protect by the mode_config lock, so drop the

			 * ref immediately */

			drm_framebuffer_unreference(fb);

		}



		mode = drm_mode_create(dev);
@@ -2156,6 +2168,9 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, 
	ret = drm_mode_set_config_internal(&set);



out:

	if (fb)

		drm_framebuffer_unreference(fb);



	kfree(connector_set);

	drm_mode_destroy(dev, mode);

	drm_modeset_unlock_all(dev);
@@ -3656,7 +3671,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev, 
	struct drm_mode_crtc_page_flip *page_flip = data;

	struct drm_mode_object *obj;

	struct drm_crtc *crtc;

	struct drm_framebuffer *fb;

	struct drm_framebuffer *fb = NULL, *old_fb = NULL;

	struct drm_pending_vblank_event *e = NULL;

	unsigned long flags;

	int hdisplay, vdisplay;
@@ -3687,8 +3702,6 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev, 
	fb = drm_framebuffer_lookup(dev, page_flip->fb_id);

	if (!fb)

		goto out;

	/* fb is protect by the mode_config lock, so drop the ref immediately */

	drm_framebuffer_unreference(fb);



	hdisplay = crtc->mode.hdisplay;

	vdisplay = crtc->mode.vdisplay;
@@ -3734,6 +3747,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev, 
			(void (*) (struct drm_pending_event *)) kfree;

	}



	old_fb = crtc->fb;

	ret = crtc->funcs->page_flip(crtc, fb, e);

	if (ret) {

		if (page_flip->flags & DRM_MODE_PAGE_FLIP_EVENT) {
@@ -3742,9 +3756,18 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev, 
			spin_unlock_irqrestore(&dev->event_lock, flags);

			kfree(e);

		}

		/* Keep the old fb, don't unref it. */

		old_fb = NULL;

	} else {

		/* Unref only the old framebuffer. */

		fb = NULL;

	}



out:

	if (fb)

		drm_framebuffer_unreference(fb);

	if (old_fb)

		drm_framebuffer_unreference(old_fb);

	drm_modeset_unlock_all(dev);

	return ret;

}