<div dir="ltr">Looking at the code I think it would be better to not use an else, but put the present_vblank_notify call before the if (vblank->abort_flip) line. Even if the flip was aborted, the client should receive a complete event. At least that's what we do in case of screen flips. </div> <div class="gmail_quote"><div dir="ltr">On Fri, Aug 24, 2018 at 11:31 PM Lionel Landwerlin <<a href="mailto:lionel.g.landwerlin@intel.com">lionel.g.landwerlin@intel.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">When a vblank has been marked as aborted, it's going to be free in the flip_notify function when stopped. We can't notify it after it's stopped because the pointer is invalid. Valgrind backtrace: ==5331== Invalid read of size 8 ==5331== at 0x212B4D: present_vblank_notify (present_vblank.c:34) ==5331== by 0x21439B: present_wnmd_flip_notify (present_wnmd.c:194) ==5331== by 0x21439B: present_wnmd_event_notify (present_wnmd.c:228) ==5331== by 0x156216: xwl_present_sync_callback (xwayland-present.c:282) ==5331== by 0x6570FCD: ffi_call_unix64 (in /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4) ==5331== by 0x657093E: ffi_call (in /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4) ==5331== by 0x4DDB183: ??? (in /usr/lib/x86_64-linux-gnu/libwayland-client.so.0.3.0) ==5331== by 0x4DD79D8: ??? (in /usr/lib/x86_64-linux-gnu/libwayland-client.so.0.3.0) ==5331== by 0x4DD8EA3: wl_display_dispatch_queue_pending (in /usr/lib/x86_64-linux-gnu/libwayland-client.so.0.3.0) ==5331== by 0x14BCCA: xwl_read_events (xwayland.c:814) ==5331== by 0x2AC0D0: ospoll_wait (ospoll.c:651) ==5331== by 0x2A5322: WaitForSomething (WaitFor.c:208) ==5331== by 0x27574B: Dispatch (dispatch.c:421) ==5331== Address 0x1b44dc98 is 40 bytes inside a block of size 184 free'd ==5331== at 0x48369EB: free (vg_replace_malloc.c:530) ==5331== by 0x213B0A: present_wnmd_free_idle_vblanks (present_wnmd.c:118) ==5331== by 0x213B0A: present_wnmd_flips_stop (present_wnmd.c:161) ==5331== by 0x2143EF: present_wnmd_flip_notify (present_wnmd.c:192) ==5331== by 0x2143EF: present_wnmd_event_notify (present_wnmd.c:228) ==5331== by 0x156216: xwl_present_sync_callback (xwayland-present.c:282) ==5331== by 0x6570FCD: ffi_call_unix64 (in /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4) ==5331== by 0x657093E: ffi_call (in /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4) ==5331== by 0x4DDB183: ??? (in /usr/lib/x86_64-linux-gnu/libwayland-client.so.0.3.0) ==5331== by 0x4DD79D8: ??? (in /usr/lib/x86_64-linux-gnu/libwayland-client.so.0.3.0) ==5331== by 0x4DD8EA3: wl_display_dispatch_queue_pending (in /usr/lib/x86_64-linux-gnu/libwayland-client.so.0.3.0) ==5331== by 0x14BCCA: xwl_read_events (xwayland.c:814) ==5331== by 0x2AC0D0: ospoll_wait (ospoll.c:651) ==5331== by 0x2A5322: WaitForSomething (WaitFor.c:208) ==5331== Block was alloc'd at ==5331== at 0x48377D5: calloc (vg_replace_malloc.c:711) ==5331== by 0x212D9F: present_vblank_create (present_vblank.c:69) ==5331== by 0x214014: present_wnmd_pixmap (present_wnmd.c:610) ==5331== by 0x21576C: proc_present_pixmap (present_request.c:150) ==5331== by 0x27599D: Dispatch (dispatch.c:479) ==5331== by 0x279945: dix_main (main.c:276) ==5331== by 0x633AB16: (below main) (libc-start.c:310) Signed-off-by: Lionel Landwerlin <<a href="mailto:lionel.g.landwerlin@intel.com" target="_blank">lionel.g.landwerlin@intel.com</a>> Reviewed-by: Daniel Stone <<a href="mailto:daniels@collabora.com" target="_blank">daniels@collabora.com</a>> Bugzilla: <a href="https://bugs.freedesktop.org/show_bug.cgi?id=107314" rel="noreferrer" target="_blank">https://bugs.freedesktop.org/show_bug.cgi?id=107314</a> --- present/present_wnmd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/present/present_wnmd.c b/present/present_wnmd.c index 80ffb014e..48f66b357 100644 --- a/present/present_wnmd.c +++ b/present/present_wnmd.c @@ -190,8 +190,9 @@ present_wnmd_flip_notify(present_vblank_ptr vblank, uint64_t ust, uint64_t crtc_ if (vblank->abort_flip) present_wnmd_flips_stop(window); + else + present_vblank_notify(vblank, PresentCompleteKindPixmap, PresentCompleteModeFlip, ust, crtc_msc); - present_vblank_notify(vblank, PresentCompleteKindPixmap, PresentCompleteModeFlip, ust, crtc_msc); present_wnmd_flip_try_ready(window); } -- 2.18.0 _______________________________________________ <a href="mailto:xorg-devel@lists.x.org" target="_blank">xorg-devel@lists.x.org</a>: X.Org development Archives: <a href="http://lists.x.org/archives/xorg-devel" rel="noreferrer" target="_blank">http://lists.x.org/archives/xorg-devel</a> Info: <a href="https://lists.x.org/mailman/listinfo/xorg-devel" rel="noreferrer" target="_blank">https://lists.x.org/mailman/listinfo/xorg-devel</a></blockquote></div>