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Peter Hutterer e57ec99b03 sync: always set the brackets (#59644)
The current code sets bracket_greater to the first trigger after the current
value, and bracket_less to the last trigger before the current value.

For example, the idle timer with three negative and three positive transitions
would set this:

         nt1       nt2                 nt3
|--------|------|--|------- idle --|---|--|-----> t
               pt1                pt2    pt3
bracket_less == nt2
bracket_greater == pt2

This is an optimization so we can skip code paths in the block/wakeup handlers
if the current value doesn't meet any of the trigger requirements. Those
handlers largely do a
   if (bracket_less is less than current value &&
       bracket_greater is greater than current value)
        return, nothing to do

However, unless the bracket values are updated at the correct time, the
following may happen:

                                      nt
|--------------|---------- idle ------|--------> t
               pt

In this case, neither bracket is set, we're past the pos transition and not
yet at the neg transition. idle may now go past nt, but the brackets are not
updated. If idle is then reset to 0, no alarm is triggered for nt. Likewise,
idle may now go past pt and no alarm is triggered.

Changing an alarm or triggering an alarm will re-calculate the brackets, so
this bug is somewhat random. If any other client triggers an alarm when the
brackets are wrongly NULL, the recalculation will set them this bug may not
appear.

This patch changes the behavior, so that the brackets are always the nearest
positive or negative transitions to the current counter value. In the example
above, nt will trigger a wakeup and a re-calculation of the brackets, so that
going past it in the negative direction will then cause the proper alarm
triggers.

Or, in Keith's words:

  Timer currently past a positive trigger
      No bracket values, because no trigger in range

  Timer moves backwards before the positive trigger
      Brackets not reset, even though there is now a trigger in range

  Timer moves forward past the positive trigger
      Trigger doesn't fire because brackets not set

Setting the LT bracket in this case will cause everything to get
re-evaluated when the sync value moves backwards before the trigger
value.

X.Org Bug 59644 <http://bugs.freedesktop.org/show_bug.cgi?id=59644>

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Keith Packard <keithp@keithp.com>
2013-10-18 16:46:33 +10:00
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damageext Merge remote-tracking branch 'ajax/xserver-next' 2013-10-04 13:50:04 -07:00
dbe dbe: Fold the window private private into the window private 2013-09-10 13:28:24 -04:00
dix sync: if the idle time was reset, force alarms to trigger (#70476) 2013-10-18 16:44:32 +10:00
doc doc: Update documentation about Windows platforms support a bit 2012-10-29 12:21:14 +00:00
exa damage: Implicitly unregister on destroy 2013-09-10 14:28:09 -04:00
fb fb: Remove unused compatibility wrappers 2013-09-10 13:29:21 -04:00
glx glx: Fill in some missing attributes from DoGetFBConfigs 2013-09-11 14:37:33 -04:00
hw Xephyr: restore cursor visibility 2013-10-14 11:07:37 +10:00
include sync: if the idle time was reset, force alarms to trigger (#70476) 2013-10-18 16:44:32 +10:00
m4 XORG_TLS: Pick the first option that works (ie: prefer __thread) 2013-02-14 09:20:47 -08:00
man Correct description of -displayfd option in man page. 2012-10-11 12:53:57 +01:00
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randr randr: Fix a copypasta bug in CRTC confinement 2013-09-10 13:26:25 -04:00
record Move extension initialisation prototypes into extinit.h 2012-07-09 23:06:41 -07:00
render Abstract cursor refcounting 2013-05-15 19:17:57 +10:00
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xfixes Abstract cursor refcounting 2013-05-15 19:17:57 +10:00
Xi Xi: allow for XIAllowEvent requests larger than XI < 2.2 size (#68554) 2013-08-30 14:26:55 +10:00
xkb xkb: don't call atoi(NULL) when parsing argv 2013-07-02 15:12:29 +10:00
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autogen.sh autogen.sh: Honor NOCONFIGURE=1 2012-10-19 13:12:33 +10:00
configure.ac configure.ac: Include missing proto declarations in SDK_REQUIRED_MODULES 2013-10-07 11:20:58 -07:00
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fix-miregion Change region implementation names to eliminate the 'mi' prefix 2010-06-05 17:47:32 -07:00
fix-miregion-private Change region implementation names to eliminate the 'mi' prefix 2010-06-05 17:47:32 -07:00
fix-patch-whitespace Rename region macros to eliminate screen argument 2010-06-05 18:59:00 -07:00
fix-region Rename region macros to eliminate screen argument 2010-06-05 18:59:00 -07:00
Makefile.am Move pseudoramiX code where it can be shared between Xwin and Xquartz 2013-08-30 12:52:30 +01:00
manpages.am Xdmx.man: Show actual configured XKB defaults instead of old hardcoded values 2011-06-21 17:54:14 -07:00
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xorg-server.pc.in xfree86: link modules against Xorg symbols on Cygwin 2012-04-05 21:57:07 -05:00
xserver.ent.in doc: relocate xserver.ent in the package root directory 2011-05-14 11:22:26 -07:00

					X Server

The X server accepts requests from client applications to create windows,
which are (normally rectangular) "virtual screens" that the client program
can draw into.

Windows are then composed on the actual screen by the X server
(or by a separate composite manager) as directed by the window manager,
which usually communicates with the user via graphical controls such as buttons
and draggable titlebars and borders.

For a comprehensive overview of X Server and X Window System, consult the
following article:
http://en.wikipedia.org/wiki/X_server

All questions regarding this software should be directed at the
Xorg mailing list:

        http://lists.freedesktop.org/mailman/listinfo/xorg

Please submit bug reports to the Xorg bugzilla:

        https://bugs.freedesktop.org/enter_bug.cgi?product=xorg

The master development code repository can be found at:

        git://anongit.freedesktop.org/git/xorg/xserver

        http://cgit.freedesktop.org/xorg/xserver

For patch submission instructions, see:

	http://www.x.org/wiki/Development/Documentation/SubmittingPatches

For more information on the git code manager, see:

        http://wiki.x.org/wiki/GitPage