From bbf470202d697b7d57cc3febad578ec77fd7bded Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 13 Jul 2015 08:22:22 +0200 Subject: [PATCH] drm/i915: fix oops in primary_check_plane MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On Sun, Jul 12, 2015 at 09:52:51AM -0700, Linus Torvalds wrote: > On Sun, Jul 12, 2015 at 1:03 AM, Jörg Otte wrote: > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000009 > > IP: [] 0xffffffffbd3447bb > > Ugh. Please enable KALLSYMS to get sane symbols. > > But yes, "crtc_state->base.active" is at offset 9 from "crtc_state", > so it's pretty clearly just that change frm > > - if (intel_crtc->active) { > + if (crtc_state->base.active) { > > and "crtc_state" is NULL. > > And the code very much knows that crtc_state can be NULL, since it's > initialized with > > crtc_state = state->base.state ? > intel_atomic_get_crtc_state(state->base.state, > intel_crtc) : NULL; > > Tssk. Daniel? Should I just revert that commit dec4f799d0a4 > ("drm/i915: Use crtc_state->active in primary check_plane func") for > now, or is there a better fix? Like just checking crtc_state for NULL? Indeed embarrassing. I've missed that we still have 1 caller left that's using the transitional helpers, and those don't fill out plane_state->state backpointers to the global atomic update since there is no global atomic update for transitional helpers. Below diff should fix this - we need to preferentially check crts_state->active and if that's not set intel_crtc->active should yield the right result for the one remaining caller (it's in the crtc_disable paths). This fixes a regression introduced in commit dec4f799d0a4c9edae20512fa60b0a36f3299ca2 Author: Daniel Vetter Date: Tue Jul 7 11:15:47 2015 +0200 drm/i915: Use crtc_state->active in primary check_plane func which was quickly reverted in commit 01e2d0627a9a6edb24c37db45db5ecb31e9de808 Author: Linus Torvalds Date: Sun Jul 12 15:00:20 2015 -0700 Revert "drm/i915: Use crtc_state->active in primary check_plane func" Cc: Linus Torvalds Cc: Jörg Otte Reported-and-tested-by: Jörg Otte Reviewed-by: Maarten Lankhorst Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 647b1404c441..85ac6d85dc39 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -13276,7 +13276,7 @@ intel_check_primary_plane(struct drm_plane *plane, if (ret) return ret; - if (intel_crtc->active) { + if (crtc_state ? crtc_state->base.active : intel_crtc->active) { struct intel_plane_state *old_state = to_intel_plane_state(plane->state); -- 2.30.2