From 412e85b605315fd129a849599cf4a5a7959573a8 Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Thu, 1 Aug 2019 18:02:15 -0400 Subject: [PATCH] drm/nouveau: Only release VCPI slots on mode changes Looks like a regression got introduced into nv50_mstc_atomic_check() that somehow didn't get found until now. If userspace changes crtc_state->active to false but leaves the CRTC enabled, we end up calling drm_dp_atomic_find_vcpi_slots() using the PBN calculated in asyh->dp.pbn. However, if the display is inactive we end up calculating a PBN of 0, which inadvertently causes us to have an allocation of 0. >From there, if userspace then disables the CRTC afterwards we end up accidentally attempting to free the VCPI twice: WARNING: CPU: 0 PID: 1484 at drivers/gpu/drm/drm_dp_mst_topology.c:3336 drm_dp_atomic_release_vcpi_slots+0x87/0xb0 [drm_kms_helper] RIP: 0010:drm_dp_atomic_release_vcpi_slots+0x87/0xb0 [drm_kms_helper] Call Trace: drm_atomic_helper_check_modeset+0x3f3/0xa60 [drm_kms_helper] ? drm_atomic_check_only+0x43/0x780 [drm] drm_atomic_helper_check+0x15/0x90 [drm_kms_helper] nv50_disp_atomic_check+0x83/0x1d0 [nouveau] drm_atomic_check_only+0x54d/0x780 [drm] ? drm_atomic_set_crtc_for_connector+0xec/0x100 [drm] drm_atomic_commit+0x13/0x50 [drm] drm_atomic_helper_set_config+0x81/0x90 [drm_kms_helper] drm_mode_setcrtc+0x194/0x6a0 [drm] ? vprintk_emit+0x16a/0x230 ? drm_ioctl+0x163/0x390 [drm] ? drm_mode_getcrtc+0x180/0x180 [drm] drm_ioctl_kernel+0xaa/0xf0 [drm] drm_ioctl+0x208/0x390 [drm] ? drm_mode_getcrtc+0x180/0x180 [drm] nouveau_drm_ioctl+0x63/0xb0 [nouveau] do_vfs_ioctl+0x405/0x660 ? recalc_sigpending+0x17/0x50 ? _copy_from_user+0x37/0x60 ksys_ioctl+0x5e/0x90 ? exit_to_usermode_loop+0x92/0xe0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x59/0x190 entry_SYSCALL_64_after_hwframe+0x44/0xa9 WARNING: CPU: 0 PID: 1484 at drivers/gpu/drm/drm_dp_mst_topology.c:3336 drm_dp_atomic_release_vcpi_slots+0x87/0xb0 [drm_kms_helper] ---[ end trace 4c395c0c51b1f88d ]--- [drm:drm_dp_atomic_release_vcpi_slots [drm_kms_helper]] *ERROR* no VCPI for [MST PORT:00000000e288eb7d] found in mst state 000000008e642070 So, fix this by doing what we probably should have done from the start: only call drm_dp_atomic_find_vcpi_slots() when crtc_state->mode_changed is set, so that VCPI allocations remain for as long as the CRTC is enabled. Signed-off-by: Lyude Paul Fixes: 232c9eec417a ("drm/nouveau: Use atomic VCPI helpers for MST") Cc: Lyude Paul Cc: Ben Skeggs Cc: Daniel Vetter Cc: David Airlie Cc: Jerry Zuo Cc: Harry Wentland Cc: Juston Li Cc: Karol Herbst Cc: Laurent Pinchart Cc: Ilia Mirkin Cc: # v5.1+ Acked-by: Ben Skeggs Signed-off-by: Dave Airlie Link: https://patchwork.freedesktop.org/patch/msgid/20190801220216.15323-1-lyude@redhat.com --- drivers/gpu/drm/nouveau/dispnv50/disp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c index 8497768f1b41..126703816794 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c @@ -780,7 +780,7 @@ nv50_msto_atomic_check(struct drm_encoder *encoder, drm_dp_calc_pbn_mode(crtc_state->adjusted_mode.clock, connector->display_info.bpc * 3); - if (drm_atomic_crtc_needs_modeset(crtc_state)) { + if (crtc_state->mode_changed) { slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr, mstc->port, asyh->dp.pbn); -- 2.30.2