From 330c422a8ee88d77407f65494f3bbf141a8d9453 Mon Sep 17 00:00:00 2001 From: Andrey Grodzovsky Date: Tue, 20 Jun 2017 13:57:06 -0400 Subject: [PATCH] drm/core: Fail atomic IOCTL with no CRTC state but with signaling. Problem : While running IGT kms_atomic_transition test suite i encountered a hang in drmHandleEvent immediately following an atomic_commit. After dumping the atomic state I relized that in this case there was not even one CRTC attached to the state and only disabled planes. This probably due to a commit which hadn't changed any property which would require attaching crtc state. This means drmHandleEvent will never wake up from read since without CRTC in atomic state the event fd will not be signaled. Fix: Protect against this issue by failing atomic_commit early in drm_mode_atomic_commit where such probelm can be identified. v2: Fix typos and extra newlines. Change-Id: I3ee28ffae35fd1e8bfe553146c44da53da02e6f8 Signed-off-by: Andrey Grodzovsky Reviewed-by: Harry Wentland Acked-by: Daniel Vetter Reviewed-by: Maarten Lankhorst Signed-off-by: Maarten Lankhorst Link: http://patchwork.freedesktop.org/patch/msgid/1497981426-27203-1-git-send-email-Andrey.Grodzovsky@amd.com --- drivers/gpu/drm/drm_atomic.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index c0f336d23f9c..095e87278a88 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -2039,7 +2039,7 @@ static int prepare_crtc_signaling(struct drm_device *dev, { struct drm_crtc *crtc; struct drm_crtc_state *crtc_state; - int i, ret; + int i, c = 0, ret; if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) return 0; @@ -2100,8 +2100,17 @@ static int prepare_crtc_signaling(struct drm_device *dev, crtc_state->event->base.fence = fence; } + + c++; } + /* + * Having this flag means user mode pends on event which will never + * reach due to lack of at least one CRTC for signaling + */ + if (c == 0 && (arg->flags & DRM_MODE_PAGE_FLIP_EVENT)) + return -EINVAL; + return 0; } -- 2.30.2