From d90e05ad487e9fe7e17c293814ac8549d9d686d8 Mon Sep 17 00:00:00 2001 From: Frank Richter Date: Mon, 14 Aug 2017 16:05:22 +0200 Subject: [PATCH] st/wgl: check for negative delta in wait_swap_interval() This can happen because of rollover. See bug report for details. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102241 Cc: mesa-stable@lists.freedesktop.org Reviewed-by: Brian Paul Reviewed-by: Jose Fonseca --- src/gallium/state_trackers/wgl/stw_framebuffer.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/src/gallium/state_trackers/wgl/stw_framebuffer.c b/src/gallium/state_trackers/wgl/stw_framebuffer.c index 321fbb6..06b5c8d 100644 --- a/src/gallium/state_trackers/wgl/stw_framebuffer.c +++ b/src/gallium/state_trackers/wgl/stw_framebuffer.c @@ -601,8 +601,11 @@ wait_swap_interval(struct stw_framebuffer *fb) int64_t min_swap_period = 1.0e6 / stw_dev->refresh_rate * stw_dev->swap_interval; - /* if time since last swap is less than wait period, wait */ - if (delta < min_swap_period) { + /* If time since last swap is less than wait period, wait. + * Note that it's possible for the delta to be negative because of + * rollover. See https://bugs.freedesktop.org/show_bug.cgi?id=102241 + */ + if ((delta >= 0) && (delta < min_swap_period)) { float fudge = 1.75f; /* emperical fudge factor */ int64_t wait = (min_swap_period - delta) * fudge; os_time_sleep(wait); -- 2.7.4