From: Daniel Vetter Date: Thu, 6 Jun 2019 22:27:47 +0000 (+0200) Subject: drm/vkms: flush crc workers earlier in commit flow X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=5ef8100a3919fb2fabae908554dc0823063e5be4;p=openwrt%2Fstaging%2Fblogic.git drm/vkms: flush crc workers earlier in commit flow Currently, we flush pending CRC workers very late in the commit flow, when we destroy all the old crtc states. Unfortunately, at that point, the framebuffers are already unpinned (and our vaddr possible gone), so this isn't good. Also, the plane_states we need might also already be cleaned up, since cleanup order of state structures isn't well defined. Fix this by waiting for all CRC workers of the old state to complete before we start any of the cleanup work. For correct ordering and avoiding races, we can only flush_work after drm_atomic_helper_wait_for_vblanks() since we know that all subsequent queue_work will be for the new state. Only once that's done is flush_work() useful, before that we might flush the work, and then right after the hrtimer that simulates vblank queues it again. Every time you have a flush_work before cleaning up the work structure, the following sequence must be obeyed, or it can go wrong: 1. Make sure no one else can re-queue the work anymore (in our case that's done by a combination of first updating output->crc_state and then waiting for the vblank to pass to make sure the hrtimer has noticed that change). 2. flush_work() 3. Actually clean up stuff (which isn't done here). Doing the flush_work before we even completed the output->state update, much less waited for the vblank to make sure that's happened, missed the point. Note that this is not yet race-free because of the hrtimer and crc worker look at the wrong state pointers, but that will be fixed in subsequent patches. Cc: Rodrigo Siqueira Cc: Haneen Mohammed Cc: Daniel Vetter Signed-off-by: Daniel Vetter Reviewed-by: Rodrigo Siqueira Tested-by: Rodrigo Siqueira Signed-off-by: Rodrigo Siqueira Link: https://patchwork.freedesktop.org/patch/msgid/20190606222751.32567-7-daniel.vetter@ffwll.ch --- diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c index 81bec95f163e..a03f361e2fe0 100644 --- a/drivers/gpu/drm/vkms/vkms_crtc.c +++ b/drivers/gpu/drm/vkms/vkms_crtc.c @@ -125,7 +125,7 @@ static void vkms_atomic_crtc_destroy_state(struct drm_crtc *crtc, __drm_atomic_helper_crtc_destroy_state(state); if (vkms_state) { - flush_work(&vkms_state->crc_work); + WARN_ON(work_pending(&vkms_state->crc_work)); kfree(vkms_state); } } diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c index f677ab1d0094..cc53ef88a331 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.c +++ b/drivers/gpu/drm/vkms/vkms_drv.c @@ -62,6 +62,9 @@ static void vkms_release(struct drm_device *dev) static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state) { struct drm_device *dev = old_state->dev; + struct drm_crtc *crtc; + struct drm_crtc_state *old_crtc_state; + int i; drm_atomic_helper_commit_modeset_disables(dev, old_state); @@ -75,6 +78,13 @@ static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state) drm_atomic_helper_wait_for_vblanks(dev, old_state); + for_each_old_crtc_in_state(old_state, crtc, old_crtc_state, i) { + struct vkms_crtc_state *vkms_state = + to_vkms_crtc_state(old_crtc_state); + + flush_work(&vkms_state->crc_work); + } + drm_atomic_helper_cleanup_planes(dev, old_state); }