From: Sean Paul seanpaul@chromium.org
Since the dirtyfb ioctl doesn't give us any hints as to which plane is scanning out the fb it's marking as damaged, we need to loop through planes to find it.
Currently we just reach into plane state and check, but that can race with another commit changing the fb out from under us. This patch locks the plane before checking the fb and will release the lock if the plane is not displaying the dirty fb.
Fixes: b9fc5e01d1ce ("drm: Add helper to implement legacy dirtyfb") Cc: Rob Clark robdclark@gmail.com Cc: Deepak Rawat drawat@vmware.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Thomas Hellstrom thellstrom@vmware.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard maxime.ripard@bootlin.com Cc: Sean Paul sean@poorly.run Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: dri-devel@lists.freedesktop.org Cc: stable@vger.kernel.org # v5.0+ Reported-by: Daniel Vetter daniel@ffwll.ch Signed-off-by: Sean Paul seanpaul@chromium.org --- drivers/gpu/drm/drm_damage_helper.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_damage_helper.c b/drivers/gpu/drm/drm_damage_helper.c index 8230dac01a89..3a4126dc2520 100644 --- a/drivers/gpu/drm/drm_damage_helper.c +++ b/drivers/gpu/drm/drm_damage_helper.c @@ -212,8 +212,14 @@ int drm_atomic_helper_dirtyfb(struct drm_framebuffer *fb, drm_for_each_plane(plane, fb->dev) { struct drm_plane_state *plane_state;
- if (plane->state->fb != fb) + ret = drm_modeset_lock(&plane->mutex, state->acquire_ctx); + if (ret) + goto out; + + if (plane->state->fb != fb) { + drm_modeset_unlock(&plane->mutex); continue; + }
plane_state = drm_atomic_get_plane_state(state, plane); if (IS_ERR(plane_state)) {