xserver

sync.c (83286B)

---

 /*
 
 Copyright 1991, 1993, 1998  The Open Group
 
 Permission to use, copy, modify, distribute, and sell this software and its
 documentation for any purpose is hereby granted without fee, provided that
 the above copyright notice appear in all copies and that both that
 copyright notice and this permission notice appear in supporting
 documentation.
 
 The above copyright notice and this permission notice shall be included
 in all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
 OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 OTHER DEALINGS IN THE SOFTWARE.
 
 Except as contained in this notice, the name of The Open Group shall
 not be used in advertising or otherwise to promote the sale, use or
 other dealings in this Software without prior written authorization
 from The Open Group.
 
 Copyright 1991, 1993 by Digital Equipment Corporation, Maynard, Massachusetts,
 and Olivetti Research Limited, Cambridge, England.
 
                         All Rights Reserved
 
 Permission to use, copy, modify, and distribute this software and its
 documentation for any purpose and without fee is hereby granted,
 provided that the above copyright notice appear in all copies and that
 both that copyright notice and this permission notice appear in
 supporting documentation, and that the names of Digital or Olivetti
 not be used in advertising or publicity pertaining to distribution of the
 software without specific, written prior permission.  Digital and Olivetti
 make no representations about the suitability of this software
 for any purpose.  It is provided "as is" without express or implied warranty.
 
 DIGITAL AND OLIVETTI DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
 SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
 FITNESS, IN NO EVENT SHALL THEY BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
 USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 PERFORMANCE OF THIS SOFTWARE.
 
 */
 
 #ifdef HAVE_DIX_CONFIG_H
 #include <dix-config.h>
 #endif
 
 #include <string.h>
 
 #include <X11/X.h>
 #include <X11/Xproto.h>
 #include <X11/Xmd.h>
 #include "scrnintstr.h"
 #include "os.h"
 #include "extnsionst.h"
 #include "dixstruct.h"
 #include "pixmapstr.h"
 #include "resource.h"
 #include "opaque.h"
 #include <X11/extensions/syncproto.h>
 #include "syncsrv.h"
 #include "syncsdk.h"
 #include "protocol-versions.h"
 #include "inputstr.h"
 
 #include <stdio.h>
 #if !defined(WIN32)
 #include <sys/time.h>
 #endif
 
 #include "extinit.h"
 
 /*
  * Local Global Variables
  */
 static int SyncEventBase;
 static int SyncErrorBase;
 static RESTYPE RTCounter = 0;
 static RESTYPE RTAwait;
 static RESTYPE RTAlarm;
 static RESTYPE RTAlarmClient;
 static RESTYPE RTFence;
 static struct xorg_list SysCounterList;
 static int SyncNumInvalidCounterWarnings = 0;
 
 #define MAX_INVALID_COUNTER_WARNINGS	   5
 
 static const char *WARN_INVALID_COUNTER_COMPARE =
     "Warning: Non-counter XSync object using Counter-only\n"
     "         comparison.  Result will never be true.\n";
 
 static const char *WARN_INVALID_COUNTER_ALARM =
     "Warning: Non-counter XSync object used in alarm.  This is\n"
     "         the result of a programming error in the X server.\n";
 
 #define IsSystemCounter(pCounter) \
     (pCounter && (pCounter->sync.client == NULL))
 
 /* these are all the alarm attributes that pertain to the alarm's trigger */
 #define XSyncCAAllTrigger \
     (XSyncCACounter | XSyncCAValueType | XSyncCAValue | XSyncCATestType)
 
 static void SyncComputeBracketValues(SyncCounter *);
 
 static void SyncInitServerTime(void);
 
 static void SyncInitIdleTime(void);
 
 static inline void*
 SysCounterGetPrivate(SyncCounter *counter)
 {
     BUG_WARN(!IsSystemCounter(counter));
 
     return counter->pSysCounterInfo ? counter->pSysCounterInfo->private : NULL;
 }
 
 static Bool
 SyncCheckWarnIsCounter(const SyncObject * pSync, const char *warning)
 {
     if (pSync && (SYNC_COUNTER != pSync->type)) {
         if (SyncNumInvalidCounterWarnings++ < MAX_INVALID_COUNTER_WARNINGS) {
             ErrorF("%s", warning);
             ErrorF("         Counter type: %d\n", pSync->type);
         }
 
         return FALSE;
     }
 
     return TRUE;
 }
 
 /*  Each counter maintains a simple linked list of triggers that are
  *  interested in the counter.  The two functions below are used to
  *  delete and add triggers on this list.
  */
 void
 SyncDeleteTriggerFromSyncObject(SyncTrigger * pTrigger)
 {
     SyncTriggerList *pCur;
     SyncTriggerList *pPrev;
     SyncCounter *pCounter;
 
     /* pSync needs to be stored in pTrigger before calling here. */
 
     if (!pTrigger->pSync)
         return;
 
     pPrev = NULL;
     pCur = pTrigger->pSync->pTriglist;
 
     while (pCur) {
         if (pCur->pTrigger == pTrigger) {
             if (pPrev)
                 pPrev->next = pCur->next;
             else
                 pTrigger->pSync->pTriglist = pCur->next;
 
             free(pCur);
             break;
         }
 
         pPrev = pCur;
         pCur = pCur->next;
     }
 
     if (SYNC_COUNTER == pTrigger->pSync->type) {
         pCounter = (SyncCounter *) pTrigger->pSync;
 
         if (IsSystemCounter(pCounter))
             SyncComputeBracketValues(pCounter);
     }
     else if (SYNC_FENCE == pTrigger->pSync->type) {
         SyncFence *pFence = (SyncFence *) pTrigger->pSync;
 
         pFence->funcs.DeleteTrigger(pTrigger);
     }
 }
 
 int
 SyncAddTriggerToSyncObject(SyncTrigger * pTrigger)
 {
     SyncTriggerList *pCur;
     SyncCounter *pCounter;
 
     if (!pTrigger->pSync)
         return Success;
 
     /* don't do anything if it's already there */
     for (pCur = pTrigger->pSync->pTriglist; pCur; pCur = pCur->next) {
         if (pCur->pTrigger == pTrigger)
             return Success;
     }
 
     if (!(pCur = malloc(sizeof(SyncTriggerList))))
         return BadAlloc;
 
     pCur->pTrigger = pTrigger;
     pCur->next = pTrigger->pSync->pTriglist;
     pTrigger->pSync->pTriglist = pCur;
 
     if (SYNC_COUNTER == pTrigger->pSync->type) {
         pCounter = (SyncCounter *) pTrigger->pSync;
 
         if (IsSystemCounter(pCounter))
             SyncComputeBracketValues(pCounter);
     }
     else if (SYNC_FENCE == pTrigger->pSync->type) {
         SyncFence *pFence = (SyncFence *) pTrigger->pSync;
 
         pFence->funcs.AddTrigger(pTrigger);
     }
 
     return Success;
 }
 
 /*  Below are five possible functions that can be plugged into
  *  pTrigger->CheckTrigger for counter sync objects, corresponding to
  *  the four possible test-types, and the one possible function that
  *  can be plugged into pTrigger->CheckTrigger for fence sync objects.
  *  These functions are called after the sync object's state changes
  *  but are also passed the old state so they can inspect both the old
  *  and new values.  (PositiveTransition and NegativeTransition need to
  *  see both pieces of information.)  These functions return the truth
  *  value of the trigger.
  *
  *  All of them include the condition pTrigger->pSync == NULL.
  *  This is because the spec says that a trigger with a sync value
  *  of None is always TRUE.
  */
 
 static Bool
 SyncCheckTriggerPositiveComparison(SyncTrigger * pTrigger, int64_t oldval)
 {
     SyncCounter *pCounter;
 
     /* Non-counter sync objects should never get here because they
      * never trigger this comparison. */
     if (!SyncCheckWarnIsCounter(pTrigger->pSync, WARN_INVALID_COUNTER_COMPARE))
         return FALSE;
 
     pCounter = (SyncCounter *) pTrigger->pSync;
 
     return pCounter == NULL || pCounter->value >= pTrigger->test_value;
 }
 
 static Bool
 SyncCheckTriggerNegativeComparison(SyncTrigger * pTrigger, int64_t oldval)
 {
     SyncCounter *pCounter;
 
     /* Non-counter sync objects should never get here because they
      * never trigger this comparison. */
     if (!SyncCheckWarnIsCounter(pTrigger->pSync, WARN_INVALID_COUNTER_COMPARE))
         return FALSE;
 
     pCounter = (SyncCounter *) pTrigger->pSync;
 
     return pCounter == NULL || pCounter->value <= pTrigger->test_value;
 }
 
 static Bool
 SyncCheckTriggerPositiveTransition(SyncTrigger * pTrigger, int64_t oldval)
 {
     SyncCounter *pCounter;
 
     /* Non-counter sync objects should never get here because they
      * never trigger this comparison. */
     if (!SyncCheckWarnIsCounter(pTrigger->pSync, WARN_INVALID_COUNTER_COMPARE))
         return FALSE;
 
     pCounter = (SyncCounter *) pTrigger->pSync;
 
     return (pCounter == NULL ||
             (oldval < pTrigger->test_value &&
              pCounter->value >= pTrigger->test_value));
 }
 
 static Bool
 SyncCheckTriggerNegativeTransition(SyncTrigger * pTrigger, int64_t oldval)
 {
     SyncCounter *pCounter;
 
     /* Non-counter sync objects should never get here because they
      * never trigger this comparison. */
     if (!SyncCheckWarnIsCounter(pTrigger->pSync, WARN_INVALID_COUNTER_COMPARE))
         return FALSE;
 
     pCounter = (SyncCounter *) pTrigger->pSync;
 
     return (pCounter == NULL ||
             (oldval > pTrigger->test_value &&
              pCounter->value <= pTrigger->test_value));
 }
 
 static Bool
 SyncCheckTriggerFence(SyncTrigger * pTrigger, int64_t unused)
 {
     SyncFence *pFence = (SyncFence *) pTrigger->pSync;
 
     (void) unused;
 
     return (pFence == NULL || pFence->funcs.CheckTriggered(pFence));
 }
 
 static int
 SyncInitTrigger(ClientPtr client, SyncTrigger * pTrigger, XID syncObject,
                 RESTYPE resType, Mask changes)
 {
     SyncObject *pSync = pTrigger->pSync;
     SyncCounter *pCounter = NULL;
     int rc;
     Bool newSyncObject = FALSE;
 
     if (changes & XSyncCACounter) {
         if (syncObject == None)
             pSync = NULL;
         else if (Success != (rc = dixLookupResourceByType((void **) &pSync,
                                                           syncObject, resType,
                                                           client,
                                                           DixReadAccess))) {
             client->errorValue = syncObject;
             return rc;
         }
         if (pSync != pTrigger->pSync) { /* new counter for trigger */
             SyncDeleteTriggerFromSyncObject(pTrigger);
             pTrigger->pSync = pSync;
             newSyncObject = TRUE;
         }
     }
 
     /* if system counter, ask it what the current value is */
 
     if (pSync && SYNC_COUNTER == pSync->type) {
         pCounter = (SyncCounter *) pSync;
 
         if (IsSystemCounter(pCounter)) {
             (*pCounter->pSysCounterInfo->QueryValue) ((void *) pCounter,
                                                       &pCounter->value);
         }
     }
 
     if (changes & XSyncCAValueType) {
         if (pTrigger->value_type != XSyncRelative &&
             pTrigger->value_type != XSyncAbsolute) {
             client->errorValue = pTrigger->value_type;
             return BadValue;
         }
     }
 
     if (changes & XSyncCATestType) {
 
         if (pSync && SYNC_FENCE == pSync->type) {
             pTrigger->CheckTrigger = SyncCheckTriggerFence;
         }
         else {
             /* select appropriate CheckTrigger function */
 
             switch (pTrigger->test_type) {
             case XSyncPositiveTransition:
                 pTrigger->CheckTrigger = SyncCheckTriggerPositiveTransition;
                 break;
             case XSyncNegativeTransition:
                 pTrigger->CheckTrigger = SyncCheckTriggerNegativeTransition;
                 break;
             case XSyncPositiveComparison:
                 pTrigger->CheckTrigger = SyncCheckTriggerPositiveComparison;
                 break;
             case XSyncNegativeComparison:
                 pTrigger->CheckTrigger = SyncCheckTriggerNegativeComparison;
                 break;
             default:
                 client->errorValue = pTrigger->test_type;
                 return BadValue;
             }
         }
     }
 
     if (changes & (XSyncCAValueType | XSyncCAValue)) {
         if (pTrigger->value_type == XSyncAbsolute)
             pTrigger->test_value = pTrigger->wait_value;
         else {                  /* relative */
             Bool overflow;
 
             if (pCounter == NULL)
                 return BadMatch;
 
             overflow = checked_int64_add(&pTrigger->test_value,
                                          pCounter->value, pTrigger->wait_value);
             if (overflow) {
                 client->errorValue = pTrigger->wait_value >> 32;
                 return BadValue;
             }
         }
     }
 
     /*  we wait until we're sure there are no errors before registering
      *  a new counter on a trigger
      */
     if (newSyncObject) {
         if ((rc = SyncAddTriggerToSyncObject(pTrigger)) != Success)
             return rc;
     }
     else if (pCounter && IsSystemCounter(pCounter)) {
         SyncComputeBracketValues(pCounter);
     }
 
     return Success;
 }
 
 /*  AlarmNotify events happen in response to actions taken on an Alarm or
  *  the counter used by the alarm.  AlarmNotify may be sent to multiple
  *  clients.  The alarm maintains a list of clients interested in events.
  */
 static void
 SyncSendAlarmNotifyEvents(SyncAlarm * pAlarm)
 {
     SyncAlarmClientList *pcl;
     xSyncAlarmNotifyEvent ane;
     SyncTrigger *pTrigger = &pAlarm->trigger;
     SyncCounter *pCounter;
 
     if (!SyncCheckWarnIsCounter(pTrigger->pSync, WARN_INVALID_COUNTER_ALARM))
         return;
 
     pCounter = (SyncCounter *) pTrigger->pSync;
 
     UpdateCurrentTime();
 
     ane = (xSyncAlarmNotifyEvent) {
         .type = SyncEventBase + XSyncAlarmNotify,
         .kind = XSyncAlarmNotify,
         .alarm = pAlarm->alarm_id,
         .alarm_value_hi = pTrigger->test_value >> 32,
         .alarm_value_lo = pTrigger->test_value,
         .time = currentTime.milliseconds,
         .state = pAlarm->state
     };
 
     if (pTrigger->pSync && SYNC_COUNTER == pTrigger->pSync->type) {
         ane.counter_value_hi = pCounter->value >> 32;
         ane.counter_value_lo = pCounter->value;
     }
     else {
         /* XXX what else can we do if there's no counter? */
         ane.counter_value_hi = ane.counter_value_lo = 0;
     }
 
     /* send to owner */
     if (pAlarm->events)
         WriteEventsToClient(pAlarm->client, 1, (xEvent *) &ane);
 
     /* send to other interested clients */
     for (pcl = pAlarm->pEventClients; pcl; pcl = pcl->next)
         WriteEventsToClient(pcl->client, 1, (xEvent *) &ane);
 }
 
 /*  CounterNotify events only occur in response to an Await.  The events
  *  go only to the Awaiting client.
  */
 static void
 SyncSendCounterNotifyEvents(ClientPtr client, SyncAwait ** ppAwait,
                             int num_events)
 {
     xSyncCounterNotifyEvent *pEvents, *pev;
     int i;
 
     if (client->clientGone)
         return;
     pev = pEvents = calloc(num_events, sizeof(xSyncCounterNotifyEvent));
     if (!pEvents)
         return;
     UpdateCurrentTime();
     for (i = 0; i < num_events; i++, ppAwait++, pev++) {
         SyncTrigger *pTrigger = &(*ppAwait)->trigger;
 
         pev->type = SyncEventBase + XSyncCounterNotify;
         pev->kind = XSyncCounterNotify;
         pev->counter = pTrigger->pSync->id;
         pev->wait_value_lo = pTrigger->test_value;
         pev->wait_value_hi = pTrigger->test_value >> 32;
         if (SYNC_COUNTER == pTrigger->pSync->type) {
             SyncCounter *pCounter = (SyncCounter *) pTrigger->pSync;
 
             pev->counter_value_lo = pCounter->value;
             pev->counter_value_hi = pCounter->value >> 32;
         }
         else {
             pev->counter_value_lo = 0;
             pev->counter_value_hi = 0;
         }
 
         pev->time = currentTime.milliseconds;
         pev->count = num_events - i - 1;        /* events remaining */
         pev->destroyed = pTrigger->pSync->beingDestroyed;
     }
     /* swapping will be taken care of by this */
     WriteEventsToClient(client, num_events, (xEvent *) pEvents);
     free(pEvents);
 }
 
 /* This function is called when an alarm's counter is destroyed.
  * It is plugged into pTrigger->CounterDestroyed (for alarm triggers).
  */
 static void
 SyncAlarmCounterDestroyed(SyncTrigger * pTrigger)
 {
     SyncAlarm *pAlarm = (SyncAlarm *) pTrigger;
 
     pAlarm->state = XSyncAlarmInactive;
     SyncSendAlarmNotifyEvents(pAlarm);
     pTrigger->pSync = NULL;
 }
 
 /*  This function is called when an alarm "goes off."
  *  It is plugged into pTrigger->TriggerFired (for alarm triggers).
  */
 static void
 SyncAlarmTriggerFired(SyncTrigger * pTrigger)
 {
     SyncAlarm *pAlarm = (SyncAlarm *) pTrigger;
     SyncCounter *pCounter;
     int64_t new_test_value;
 
     if (!SyncCheckWarnIsCounter(pTrigger->pSync, WARN_INVALID_COUNTER_ALARM))
         return;
 
     pCounter = (SyncCounter *) pTrigger->pSync;
 
     /* no need to check alarm unless it's active */
     if (pAlarm->state != XSyncAlarmActive)
         return;
 
     /*  " if the counter value is None, or if the delta is 0 and
      *    the test-type is PositiveComparison or NegativeComparison,
      *    no change is made to value (test-value) and the alarm
      *    state is changed to Inactive before the event is generated."
      */
     if (pCounter == NULL || (pAlarm->delta == 0
                              && (pAlarm->trigger.test_type ==
                                  XSyncPositiveComparison ||
                                  pAlarm->trigger.test_type ==
                                  XSyncNegativeComparison)))
         pAlarm->state = XSyncAlarmInactive;
 
     new_test_value = pAlarm->trigger.test_value;
 
     if (pAlarm->state == XSyncAlarmActive) {
         Bool overflow;
         int64_t oldvalue;
         SyncTrigger *paTrigger = &pAlarm->trigger;
         SyncCounter *paCounter;
 
         if (!SyncCheckWarnIsCounter(paTrigger->pSync,
                                     WARN_INVALID_COUNTER_ALARM))
             return;
 
         paCounter = (SyncCounter *) pTrigger->pSync;
 
         /* "The alarm is updated by repeatedly adding delta to the
          *  value of the trigger and re-initializing it until it
          *  becomes FALSE."
          */
         oldvalue = paTrigger->test_value;
 
         /* XXX really should do something smarter here */
 
         do {
             overflow = checked_int64_add(&paTrigger->test_value,
                                          paTrigger->test_value, pAlarm->delta);
         } while (!overflow &&
                  (*paTrigger->CheckTrigger) (paTrigger, paCounter->value));
 
         new_test_value = paTrigger->test_value;
         paTrigger->test_value = oldvalue;
 
         /* "If this update would cause value to fall outside the range
          *  for an INT64...no change is made to value (test-value) and
          *  the alarm state is changed to Inactive before the event is
          *  generated."
          */
         if (overflow) {
             new_test_value = oldvalue;
             pAlarm->state = XSyncAlarmInactive;
         }
     }
     /*  The AlarmNotify event has to have the "new state of the alarm"
      *  which we can't be sure of until this point.  However, it has
      *  to have the "old" trigger test value.  That's the reason for
      *  all the newvalue/oldvalue shuffling above.  After we send the
      *  events, give the trigger its new test value.
      */
     SyncSendAlarmNotifyEvents(pAlarm);
     pTrigger->test_value = new_test_value;
 }
 
 /*  This function is called when an Await unblocks, either as a result
  *  of the trigger firing OR the counter being destroyed.
  *  It goes into pTrigger->TriggerFired AND pTrigger->CounterDestroyed
  *  (for Await triggers).
  */
 static void
 SyncAwaitTriggerFired(SyncTrigger * pTrigger)
 {
     SyncAwait *pAwait = (SyncAwait *) pTrigger;
     int numwaits;
     SyncAwaitUnion *pAwaitUnion;
     SyncAwait **ppAwait;
     int num_events = 0;
 
     pAwaitUnion = (SyncAwaitUnion *) pAwait->pHeader;
     numwaits = pAwaitUnion->header.num_waitconditions;
     ppAwait = xallocarray(numwaits, sizeof(SyncAwait *));
     if (!ppAwait)
         goto bail;
 
     pAwait = &(pAwaitUnion + 1)->await;
 
     /* "When a client is unblocked, all the CounterNotify events for
      *  the Await request are generated contiguously. If count is 0
      *  there are no more events to follow for this request. If
      *  count is n, there are at least n more events to follow."
      *
      *  Thus, it is best to find all the counters for which events
      *  need to be sent first, so that an accurate count field can
      *  be stored in the events.
      */
     for (; numwaits; numwaits--, pAwait++) {
         int64_t diff;
         Bool overflow, diffgreater, diffequal;
 
         /* "A CounterNotify event with the destroyed flag set to TRUE is
          *  always generated if the counter for one of the triggers is
          *  destroyed."
          */
         if (pAwait->trigger.pSync->beingDestroyed) {
             ppAwait[num_events++] = pAwait;
             continue;
         }
 
         if (SYNC_COUNTER == pAwait->trigger.pSync->type) {
             SyncCounter *pCounter = (SyncCounter *) pAwait->trigger.pSync;
 
             /* "The difference between the counter and the test value is
              *  calculated by subtracting the test value from the value of
              *  the counter."
              */
             overflow = checked_int64_subtract(&diff, pCounter->value,
                                               pAwait->trigger.test_value);
 
             /* "If the difference lies outside the range for an INT64, an
              *  event is not generated."
              */
             if (overflow)
                 continue;
             diffgreater = diff > pAwait->event_threshold;
             diffequal = diff == pAwait->event_threshold;
 
             /* "If the test-type is PositiveTransition or
              *  PositiveComparison, a CounterNotify event is generated if
              *  the difference is at least event-threshold. If the test-type
              *  is NegativeTransition or NegativeComparison, a CounterNotify
              *  event is generated if the difference is at most
              *  event-threshold."
              */
 
             if (((pAwait->trigger.test_type == XSyncPositiveComparison ||
                   pAwait->trigger.test_type == XSyncPositiveTransition)
                  && (diffgreater || diffequal))
                 ||
                 ((pAwait->trigger.test_type == XSyncNegativeComparison ||
                   pAwait->trigger.test_type == XSyncNegativeTransition)
                  && (!diffgreater)      /* less or equal */
                 )
                 ) {
                 ppAwait[num_events++] = pAwait;
             }
         }
     }
     if (num_events)
         SyncSendCounterNotifyEvents(pAwaitUnion->header.client, ppAwait,
                                     num_events);
     free(ppAwait);
 
  bail:
     /* unblock the client */
     AttendClient(pAwaitUnion->header.client);
     /* delete the await */
     FreeResource(pAwaitUnion->header.delete_id, RT_NONE);
 }
 
 static int64_t
 SyncUpdateCounter(SyncCounter *pCounter, int64_t newval)
 {
     int64_t oldval = pCounter->value;
     pCounter->value = newval;
     return oldval;
 }
 
 /*  This function should always be used to change a counter's value so that
  *  any triggers depending on the counter will be checked.
  */
 void
 SyncChangeCounter(SyncCounter * pCounter, int64_t newval)
 {
     SyncTriggerList *ptl, *pnext;
     int64_t oldval;
 
     oldval = SyncUpdateCounter(pCounter, newval);
 
     /* run through triggers to see if any become true */
     for (ptl = pCounter->sync.pTriglist; ptl; ptl = pnext) {
         pnext = ptl->next;
         if ((*ptl->pTrigger->CheckTrigger) (ptl->pTrigger, oldval))
             (*ptl->pTrigger->TriggerFired) (ptl->pTrigger);
     }
 
     if (IsSystemCounter(pCounter)) {
         SyncComputeBracketValues(pCounter);
     }
 }
 
 /* loosely based on dix/events.c/EventSelectForWindow */
 static Bool
 SyncEventSelectForAlarm(SyncAlarm * pAlarm, ClientPtr client, Bool wantevents)
 {
     SyncAlarmClientList *pClients;
 
     if (client == pAlarm->client) {     /* alarm owner */
         pAlarm->events = wantevents;
         return Success;
     }
 
     /* see if the client is already on the list (has events selected) */
 
     for (pClients = pAlarm->pEventClients; pClients; pClients = pClients->next) {
         if (pClients->client == client) {
             /* client's presence on the list indicates desire for
              * events.  If the client doesn't want events, remove it
              * from the list.  If the client does want events, do
              * nothing, since it's already got them.
              */
             if (!wantevents) {
                 FreeResource(pClients->delete_id, RT_NONE);
             }
             return Success;
         }
     }
 
     /*  if we get here, this client does not currently have
      *  events selected on the alarm
      */
 
     if (!wantevents)
         /* client doesn't want events, and we just discovered that it
          * doesn't have them, so there's nothing to do.
          */
         return Success;
 
     /* add new client to pAlarm->pEventClients */
 
     pClients = malloc(sizeof(SyncAlarmClientList));
     if (!pClients)
         return BadAlloc;
 
     /*  register it as a resource so it will be cleaned up
      *  if the client dies
      */
 
     pClients->delete_id = FakeClientID(client->index);
 
     /* link it into list after we know all the allocations succeed */
     pClients->next = pAlarm->pEventClients;
     pAlarm->pEventClients = pClients;
     pClients->client = client;
 
     if (!AddResource(pClients->delete_id, RTAlarmClient, pAlarm))
         return BadAlloc;
 
     return Success;
 }
 
 /*
  * ** SyncChangeAlarmAttributes ** This is used by CreateAlarm and ChangeAlarm
  */
 static int
 SyncChangeAlarmAttributes(ClientPtr client, SyncAlarm * pAlarm, Mask mask,
                           CARD32 *values)
 {
     int status;
     XSyncCounter counter;
     Mask origmask = mask;
 
     counter = pAlarm->trigger.pSync ? pAlarm->trigger.pSync->id : None;
 
     while (mask) {
         int index2 = lowbit(mask);
 
         mask &= ~index2;
         switch (index2) {
         case XSyncCACounter:
             mask &= ~XSyncCACounter;
             /* sanity check in SyncInitTrigger */
             counter = *values++;
             break;
 
         case XSyncCAValueType:
             mask &= ~XSyncCAValueType;
             /* sanity check in SyncInitTrigger */
             pAlarm->trigger.value_type = *values++;
             break;
 
         case XSyncCAValue:
             mask &= ~XSyncCAValue;
             pAlarm->trigger.wait_value = ((int64_t)values[0] << 32) | values[1];
             values += 2;
             break;
 
         case XSyncCATestType:
             mask &= ~XSyncCATestType;
             /* sanity check in SyncInitTrigger */
             pAlarm->trigger.test_type = *values++;
             break;
 
         case XSyncCADelta:
             mask &= ~XSyncCADelta;
             pAlarm->delta = ((int64_t)values[0] << 32) | values[1];
             values += 2;
             break;
 
         case XSyncCAEvents:
             mask &= ~XSyncCAEvents;
             if ((*values != xTrue) && (*values != xFalse)) {
                 client->errorValue = *values;
                 return BadValue;
             }
             status = SyncEventSelectForAlarm(pAlarm, client,
                                              (Bool) (*values++));
             if (status != Success)
                 return status;
             break;
 
         default:
             client->errorValue = mask;
             return BadValue;
         }
     }
 
     /* "If the test-type is PositiveComparison or PositiveTransition
      *  and delta is less than zero, or if the test-type is
      *  NegativeComparison or NegativeTransition and delta is
      *  greater than zero, a Match error is generated."
      */
     if (origmask & (XSyncCADelta | XSyncCATestType)) {
         if ((((pAlarm->trigger.test_type == XSyncPositiveComparison) ||
               (pAlarm->trigger.test_type == XSyncPositiveTransition))
              && pAlarm->delta < 0)
             ||
             (((pAlarm->trigger.test_type == XSyncNegativeComparison) ||
               (pAlarm->trigger.test_type == XSyncNegativeTransition))
              && pAlarm->delta > 0)
             ) {
             return BadMatch;
         }
     }
 
     /* postpone this until now, when we're sure nothing else can go wrong */
     if ((status = SyncInitTrigger(client, &pAlarm->trigger, counter, RTCounter,
                                   origmask & XSyncCAAllTrigger)) != Success)
         return status;
 
     /* XXX spec does not really say to do this - needs clarification */
     pAlarm->state = XSyncAlarmActive;
     return Success;
 }
 
 SyncObject *
 SyncCreate(ClientPtr client, XID id, unsigned char type)
 {
     SyncObject *pSync;
     RESTYPE resType;
 
     switch (type) {
     case SYNC_COUNTER:
         pSync = malloc(sizeof(SyncCounter));
         resType = RTCounter;
         break;
     case SYNC_FENCE:
         pSync = (SyncObject *) dixAllocateObjectWithPrivates(SyncFence,
                                                              PRIVATE_SYNC_FENCE);
         resType = RTFence;
         break;
     default:
         return NULL;
     }
 
     if (!pSync)
         return NULL;
 
     pSync->initialized = FALSE;
 
     if (!AddResource(id, resType, (void *) pSync))
         return NULL;
 
     pSync->client = client;
     pSync->id = id;
     pSync->pTriglist = NULL;
     pSync->beingDestroyed = FALSE;
     pSync->type = type;
 
     return pSync;
 }
 
 int
 SyncCreateFenceFromFD(ClientPtr client, DrawablePtr pDraw, XID id, int fd, BOOL initially_triggered)
 {
 #ifdef HAVE_XSHMFENCE
     SyncFence  *pFence;
     int         status;
 
     pFence = (SyncFence *) SyncCreate(client, id, SYNC_FENCE);
     if (!pFence)
         return BadAlloc;
 
     status = miSyncInitFenceFromFD(pDraw, pFence, fd, initially_triggered);
     if (status != Success) {
         FreeResource(pFence->sync.id, RT_NONE);
         return status;
     }
 
     return Success;
 #else
     return BadImplementation;
 #endif
 }
 
 int
 SyncFDFromFence(ClientPtr client, DrawablePtr pDraw, SyncFence *pFence)
 {
 #ifdef HAVE_XSHMFENCE
     return miSyncFDFromFence(pDraw, pFence);
 #else
     return BadImplementation;
 #endif
 }
 
 static SyncCounter *
 SyncCreateCounter(ClientPtr client, XSyncCounter id, int64_t initialvalue)
 {
     SyncCounter *pCounter;
 
     if (!(pCounter = (SyncCounter *) SyncCreate(client, id, SYNC_COUNTER)))
         return NULL;
 
     pCounter->value = initialvalue;
     pCounter->pSysCounterInfo = NULL;
 
     pCounter->sync.initialized = TRUE;
 
     return pCounter;
 }
 
 static int FreeCounter(void *, XID);
 
 /*
  * ***** System Counter utilities
  */
 
 SyncCounter*
 SyncCreateSystemCounter(const char *name,
                         int64_t initial,
                         int64_t resolution,
                         SyncCounterType counterType,
                         SyncSystemCounterQueryValue QueryValue,
                         SyncSystemCounterBracketValues BracketValues
     )
 {
     SyncCounter *pCounter = SyncCreateCounter(NULL, FakeClientID(0), initial);
 
     if (pCounter) {
         SysCounterInfo *psci;
 
         psci = malloc(sizeof(SysCounterInfo));
         if (!psci) {
             FreeResource(pCounter->sync.id, RT_NONE);
             return pCounter;
         }
         pCounter->pSysCounterInfo = psci;
         psci->pCounter = pCounter;
         psci->name = strdup(name);
         psci->resolution = resolution;
         psci->counterType = counterType;
         psci->QueryValue = QueryValue;
         psci->BracketValues = BracketValues;
         psci->private = NULL;
         psci->bracket_greater = LLONG_MAX;
         psci->bracket_less = LLONG_MIN;
         xorg_list_add(&psci->entry, &SysCounterList);
     }
     return pCounter;
 }
 
 void
 SyncDestroySystemCounter(void *pSysCounter)
 {
     SyncCounter *pCounter = (SyncCounter *) pSysCounter;
 
     FreeResource(pCounter->sync.id, RT_NONE);
 }
 
 static void
 SyncComputeBracketValues(SyncCounter * pCounter)
 {
     SyncTriggerList *pCur;
     SyncTrigger *pTrigger;
     SysCounterInfo *psci;
     int64_t *pnewgtval = NULL;
     int64_t *pnewltval = NULL;
     SyncCounterType ct;
 
     if (!pCounter)
         return;
 
     psci = pCounter->pSysCounterInfo;
     ct = pCounter->pSysCounterInfo->counterType;
     if (ct == XSyncCounterNeverChanges)
         return;
 
     psci->bracket_greater = LLONG_MAX;
     psci->bracket_less = LLONG_MIN;
 
     for (pCur = pCounter->sync.pTriglist; pCur; pCur = pCur->next) {
         pTrigger = pCur->pTrigger;
 
         if (pTrigger->test_type == XSyncPositiveComparison &&
             ct != XSyncCounterNeverIncreases) {
             if (pCounter->value < pTrigger->test_value &&
                 pTrigger->test_value < psci->bracket_greater) {
                 psci->bracket_greater = pTrigger->test_value;
                 pnewgtval = &psci->bracket_greater;
             }
             else if (pCounter->value > pTrigger->test_value &&
                      pTrigger->test_value > psci->bracket_less) {
                     psci->bracket_less = pTrigger->test_value;
                     pnewltval = &psci->bracket_less;
             }
         }
         else if (pTrigger->test_type == XSyncNegativeComparison &&
                  ct != XSyncCounterNeverDecreases) {
             if (pCounter->value > pTrigger->test_value &&
                 pTrigger->test_value > psci->bracket_less) {
                 psci->bracket_less = pTrigger->test_value;
                 pnewltval = &psci->bracket_less;
             }
             else if (pCounter->value < pTrigger->test_value &&
                      pTrigger->test_value < psci->bracket_greater) {
                     psci->bracket_greater = pTrigger->test_value;
                     pnewgtval = &psci->bracket_greater;
             }
         }
         else if (pTrigger->test_type == XSyncNegativeTransition &&
                  ct != XSyncCounterNeverIncreases) {
             if (pCounter->value >= pTrigger->test_value &&
                 pTrigger->test_value > psci->bracket_less) {
                     /*
                      * If the value is exactly equal to our threshold, we want one
                      * more event in the negative direction to ensure we pick up
                      * when the value is less than this threshold.
                      */
                     psci->bracket_less = pTrigger->test_value;
                     pnewltval = &psci->bracket_less;
             }
             else if (pCounter->value < pTrigger->test_value &&
                      pTrigger->test_value < psci->bracket_greater) {
                     psci->bracket_greater = pTrigger->test_value;
                     pnewgtval = &psci->bracket_greater;
             }
         }
         else if (pTrigger->test_type == XSyncPositiveTransition &&
                  ct != XSyncCounterNeverDecreases) {
             if (pCounter->value <= pTrigger->test_value &&
                 pTrigger->test_value < psci->bracket_greater) {
                     /*
                      * If the value is exactly equal to our threshold, we
                      * want one more event in the positive direction to
                      * ensure we pick up when the value *exceeds* this
                      * threshold.
                      */
                     psci->bracket_greater = pTrigger->test_value;
                     pnewgtval = &psci->bracket_greater;
             }
             else if (pCounter->value > pTrigger->test_value &&
                      pTrigger->test_value > psci->bracket_less) {
                     psci->bracket_less = pTrigger->test_value;
                     pnewltval = &psci->bracket_less;
             }
         }
     }                           /* end for each trigger */
 
     (*psci->BracketValues) ((void *) pCounter, pnewltval, pnewgtval);
 
 }
 
 /*
  * *****  Resource delete functions
  */
 
 /* ARGSUSED */
 static int
 FreeAlarm(void *addr, XID id)
 {
     SyncAlarm *pAlarm = (SyncAlarm *) addr;
 
     pAlarm->state = XSyncAlarmDestroyed;
 
     SyncSendAlarmNotifyEvents(pAlarm);
 
     /* delete event selections */
 
     while (pAlarm->pEventClients)
         FreeResource(pAlarm->pEventClients->delete_id, RT_NONE);
 
     SyncDeleteTriggerFromSyncObject(&pAlarm->trigger);
 
     free(pAlarm);
     return Success;
 }
 
 /*
  * ** Cleanup after the destruction of a Counter
  */
 /* ARGSUSED */
 static int
 FreeCounter(void *env, XID id)
 {
     SyncCounter *pCounter = (SyncCounter *) env;
 
     pCounter->sync.beingDestroyed = TRUE;
 
     if (pCounter->sync.initialized) {
         SyncTriggerList *ptl, *pnext;
 
         /* tell all the counter's triggers that counter has been destroyed */
         for (ptl = pCounter->sync.pTriglist; ptl; ptl = pnext) {
             (*ptl->pTrigger->CounterDestroyed) (ptl->pTrigger);
             pnext = ptl->next;
             free(ptl); /* destroy the trigger list as we go */
         }
         if (IsSystemCounter(pCounter)) {
             xorg_list_del(&pCounter->pSysCounterInfo->entry);
             free(pCounter->pSysCounterInfo->name);
             free(pCounter->pSysCounterInfo->private);
             free(pCounter->pSysCounterInfo);
         }
     }
 
     free(pCounter);
     return Success;
 }
 
 /*
  * ** Cleanup after Await
  */
 /* ARGSUSED */
 static int
 FreeAwait(void *addr, XID id)
 {
     SyncAwaitUnion *pAwaitUnion = (SyncAwaitUnion *) addr;
     SyncAwait *pAwait;
     int numwaits;
 
     pAwait = &(pAwaitUnion + 1)->await; /* first await on list */
 
     /* remove triggers from counters */
 
     for (numwaits = pAwaitUnion->header.num_waitconditions; numwaits;
          numwaits--, pAwait++) {
         /* If the counter is being destroyed, FreeCounter will delete
          * the trigger list itself, so don't do it here.
          */
         SyncObject *pSync = pAwait->trigger.pSync;
 
         if (pSync && !pSync->beingDestroyed)
             SyncDeleteTriggerFromSyncObject(&pAwait->trigger);
     }
     free(pAwaitUnion);
     return Success;
 }
 
 /* loosely based on dix/events.c/OtherClientGone */
 static int
 FreeAlarmClient(void *value, XID id)
 {
     SyncAlarm *pAlarm = (SyncAlarm *) value;
     SyncAlarmClientList *pCur, *pPrev;
 
     for (pPrev = NULL, pCur = pAlarm->pEventClients;
          pCur; pPrev = pCur, pCur = pCur->next) {
         if (pCur->delete_id == id) {
             if (pPrev)
                 pPrev->next = pCur->next;
             else
                 pAlarm->pEventClients = pCur->next;
             free(pCur);
             return Success;
         }
     }
     FatalError("alarm client not on event list");
  /*NOTREACHED*/}
 
 /*
  * *****  Proc functions
  */
 
 /*
  * ** Initialize the extension
  */
 static int
 ProcSyncInitialize(ClientPtr client)
 {
     xSyncInitializeReply rep = {
         .type = X_Reply,
         .sequenceNumber = client->sequence,
         .length = 0,
         .majorVersion = SERVER_SYNC_MAJOR_VERSION,
         .minorVersion = SERVER_SYNC_MINOR_VERSION,
     };
 
     REQUEST_SIZE_MATCH(xSyncInitializeReq);
 
     if (client->swapped) {
         swaps(&rep.sequenceNumber);
     }
     WriteToClient(client, sizeof(rep), &rep);
     return Success;
 }
 
 /*
  * ** Get list of system counters available through the extension
  */
 static int
 ProcSyncListSystemCounters(ClientPtr client)
 {
     xSyncListSystemCountersReply rep = {
         .type = X_Reply,
         .sequenceNumber = client->sequence,
         .nCounters = 0,
     };
     SysCounterInfo *psci;
     int len = 0;
     xSyncSystemCounter *list = NULL, *walklist = NULL;
 
     REQUEST_SIZE_MATCH(xSyncListSystemCountersReq);
 
     xorg_list_for_each_entry(psci, &SysCounterList, entry) {
         /* pad to 4 byte boundary */
         len += pad_to_int32(sz_xSyncSystemCounter + strlen(psci->name));
         ++rep.nCounters;
     }
 
     if (len) {
         walklist = list = malloc(len);
         if (!list)
             return BadAlloc;
     }
 
     rep.length = bytes_to_int32(len);
 
     if (client->swapped) {
         swaps(&rep.sequenceNumber);
         swapl(&rep.length);
         swapl(&rep.nCounters);
     }
 
     xorg_list_for_each_entry(psci, &SysCounterList, entry) {
         int namelen;
         char *pname_in_reply;
 
         walklist->counter = psci->pCounter->sync.id;
         walklist->resolution_hi = psci->resolution >> 32;
         walklist->resolution_lo = psci->resolution;
         namelen = strlen(psci->name);
         walklist->name_length = namelen;
 
         if (client->swapped) {
             swapl(&walklist->counter);
             swapl(&walklist->resolution_hi);
             swapl(&walklist->resolution_lo);
             swaps(&walklist->name_length);
         }
 
         pname_in_reply = ((char *) walklist) + sz_xSyncSystemCounter;
         strncpy(pname_in_reply, psci->name, namelen);
         walklist = (xSyncSystemCounter *) (((char *) walklist) +
                                            pad_to_int32(sz_xSyncSystemCounter +
                                                         namelen));
     }
 
     WriteToClient(client, sizeof(rep), &rep);
     if (len) {
         WriteToClient(client, len, list);
         free(list);
     }
 
     return Success;
 }
 
 /*
  * ** Set client Priority
  */
 static int
 ProcSyncSetPriority(ClientPtr client)
 {
     REQUEST(xSyncSetPriorityReq);
     ClientPtr priorityclient;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncSetPriorityReq);
 
     if (stuff->id == None)
         priorityclient = client;
     else {
         rc = dixLookupClient(&priorityclient, stuff->id, client,
                              DixSetAttrAccess);
         if (rc != Success)
             return rc;
     }
 
     if (priorityclient->priority != stuff->priority) {
         priorityclient->priority = stuff->priority;
 
         /*  The following will force the server back into WaitForSomething
          *  so that the change in this client's priority is immediately
          *  reflected.
          */
         isItTimeToYield = TRUE;
         dispatchException |= DE_PRIORITYCHANGE;
     }
     return Success;
 }
 
 /*
  * ** Get client Priority
  */
 static int
 ProcSyncGetPriority(ClientPtr client)
 {
     REQUEST(xSyncGetPriorityReq);
     xSyncGetPriorityReply rep;
     ClientPtr priorityclient;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncGetPriorityReq);
 
     if (stuff->id == None)
         priorityclient = client;
     else {
         rc = dixLookupClient(&priorityclient, stuff->id, client,
                              DixGetAttrAccess);
         if (rc != Success)
             return rc;
     }
 
     rep = (xSyncGetPriorityReply) {
         .type = X_Reply,
         .sequenceNumber = client->sequence,
         .length = 0,
         .priority = priorityclient->priority
     };
 
     if (client->swapped) {
         swaps(&rep.sequenceNumber);
         swapl(&rep.priority);
     }
 
     WriteToClient(client, sizeof(xSyncGetPriorityReply), &rep);
 
     return Success;
 }
 
 /*
  * ** Create a new counter
  */
 static int
 ProcSyncCreateCounter(ClientPtr client)
 {
     REQUEST(xSyncCreateCounterReq);
     int64_t initial;
 
     REQUEST_SIZE_MATCH(xSyncCreateCounterReq);
 
     LEGAL_NEW_RESOURCE(stuff->cid, client);
 
     initial = ((int64_t)stuff->initial_value_hi << 32) | stuff->initial_value_lo;
 
     if (!SyncCreateCounter(client, stuff->cid, initial))
         return BadAlloc;
 
     return Success;
 }
 
 /*
  * ** Set Counter value
  */
 static int
 ProcSyncSetCounter(ClientPtr client)
 {
     REQUEST(xSyncSetCounterReq);
     SyncCounter *pCounter;
     int64_t newvalue;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncSetCounterReq);
 
     rc = dixLookupResourceByType((void **) &pCounter, stuff->cid, RTCounter,
                                  client, DixWriteAccess);
     if (rc != Success)
         return rc;
 
     if (IsSystemCounter(pCounter)) {
         client->errorValue = stuff->cid;
         return BadAccess;
     }
 
     newvalue = ((int64_t)stuff->value_hi << 32) | stuff->value_lo;
     SyncChangeCounter(pCounter, newvalue);
     return Success;
 }
 
 /*
  * ** Change Counter value
  */
 static int
 ProcSyncChangeCounter(ClientPtr client)
 {
     REQUEST(xSyncChangeCounterReq);
     SyncCounter *pCounter;
     int64_t newvalue;
     Bool overflow;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncChangeCounterReq);
 
     rc = dixLookupResourceByType((void **) &pCounter, stuff->cid, RTCounter,
                                  client, DixWriteAccess);
     if (rc != Success)
         return rc;
 
     if (IsSystemCounter(pCounter)) {
         client->errorValue = stuff->cid;
         return BadAccess;
     }
 
     newvalue = (int64_t)stuff->value_hi << 32 | stuff->value_lo;
     overflow = checked_int64_add(&newvalue, newvalue, pCounter->value);
     if (overflow) {
         /* XXX 64 bit value can't fit in 32 bits; do the best we can */
         client->errorValue = stuff->value_hi;
         return BadValue;
     }
     SyncChangeCounter(pCounter, newvalue);
     return Success;
 }
 
 /*
  * ** Destroy a counter
  */
 static int
 ProcSyncDestroyCounter(ClientPtr client)
 {
     REQUEST(xSyncDestroyCounterReq);
     SyncCounter *pCounter;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncDestroyCounterReq);
 
     rc = dixLookupResourceByType((void **) &pCounter, stuff->counter,
                                  RTCounter, client, DixDestroyAccess);
     if (rc != Success)
         return rc;
 
     if (IsSystemCounter(pCounter)) {
         client->errorValue = stuff->counter;
         return BadAccess;
     }
     FreeResource(pCounter->sync.id, RT_NONE);
     return Success;
 }
 
 static SyncAwaitUnion *
 SyncAwaitPrologue(ClientPtr client, int items)
 {
     SyncAwaitUnion *pAwaitUnion;
 
     /*  all the memory for the entire await list is allocated
      *  here in one chunk
      */
     pAwaitUnion = xallocarray(items + 1, sizeof(SyncAwaitUnion));
     if (!pAwaitUnion)
         return NULL;
 
     /* first item is the header, remainder are real wait conditions */
 
     pAwaitUnion->header.delete_id = FakeClientID(client->index);
     pAwaitUnion->header.client = client;
     pAwaitUnion->header.num_waitconditions = 0;
 
     if (!AddResource(pAwaitUnion->header.delete_id, RTAwait, pAwaitUnion))
         return NULL;
 
     return pAwaitUnion;
 }
 
 static void
 SyncAwaitEpilogue(ClientPtr client, int items, SyncAwaitUnion * pAwaitUnion)
 {
     SyncAwait *pAwait;
     int i;
 
     IgnoreClient(client);
 
     /* see if any of the triggers are already true */
 
     pAwait = &(pAwaitUnion + 1)->await; /* skip over header */
     for (i = 0; i < items; i++, pAwait++) {
         int64_t value;
 
         /*  don't have to worry about NULL counters because the request
          *  errors before we get here out if they occur
          */
         switch (pAwait->trigger.pSync->type) {
         case SYNC_COUNTER:
             value = ((SyncCounter *) pAwait->trigger.pSync)->value;
             break;
         default:
             value = 0;
         }
 
         if ((*pAwait->trigger.CheckTrigger) (&pAwait->trigger, value)) {
             (*pAwait->trigger.TriggerFired) (&pAwait->trigger);
             break;              /* once is enough */
         }
     }
 }
 
 /*
  * ** Await
  */
 static int
 ProcSyncAwait(ClientPtr client)
 {
     REQUEST(xSyncAwaitReq);
     int len, items;
     int i;
     xSyncWaitCondition *pProtocolWaitConds;
     SyncAwaitUnion *pAwaitUnion;
     SyncAwait *pAwait;
     int status;
 
     REQUEST_AT_LEAST_SIZE(xSyncAwaitReq);
 
     len = client->req_len << 2;
     len -= sz_xSyncAwaitReq;
     items = len / sz_xSyncWaitCondition;
 
     if (items * sz_xSyncWaitCondition != len) {
         return BadLength;
     }
     if (items == 0) {
         client->errorValue = items;     /* XXX protocol change */
         return BadValue;
     }
 
     if (!(pAwaitUnion = SyncAwaitPrologue(client, items)))
         return BadAlloc;
 
     /* don't need to do any more memory allocation for this request! */
 
     pProtocolWaitConds = (xSyncWaitCondition *) &stuff[1];
 
     pAwait = &(pAwaitUnion + 1)->await; /* skip over header */
     for (i = 0; i < items; i++, pProtocolWaitConds++, pAwait++) {
         if (pProtocolWaitConds->counter == None) {      /* XXX protocol change */
             /*  this should take care of removing any triggers created by
              *  this request that have already been registered on sync objects
              */
             FreeResource(pAwaitUnion->header.delete_id, RT_NONE);
             client->errorValue = pProtocolWaitConds->counter;
             return SyncErrorBase + XSyncBadCounter;
         }
 
         /* sanity checks are in SyncInitTrigger */
         pAwait->trigger.pSync = NULL;
         pAwait->trigger.value_type = pProtocolWaitConds->value_type;
         pAwait->trigger.wait_value =
             ((int64_t)pProtocolWaitConds->wait_value_hi << 32) |
             pProtocolWaitConds->wait_value_lo;
         pAwait->trigger.test_type = pProtocolWaitConds->test_type;
 
         status = SyncInitTrigger(client, &pAwait->trigger,
                                  pProtocolWaitConds->counter, RTCounter,
                                  XSyncCAAllTrigger);
         if (status != Success) {
             /*  this should take care of removing any triggers created by
              *  this request that have already been registered on sync objects
              */
             FreeResource(pAwaitUnion->header.delete_id, RT_NONE);
             return status;
         }
         /* this is not a mistake -- same function works for both cases */
         pAwait->trigger.TriggerFired = SyncAwaitTriggerFired;
         pAwait->trigger.CounterDestroyed = SyncAwaitTriggerFired;
         pAwait->event_threshold =
             ((int64_t) pProtocolWaitConds->event_threshold_hi << 32) |
             pProtocolWaitConds->event_threshold_lo;
 
         pAwait->pHeader = &pAwaitUnion->header;
         pAwaitUnion->header.num_waitconditions++;
     }
 
     SyncAwaitEpilogue(client, items, pAwaitUnion);
 
     return Success;
 }
 
 /*
  * ** Query a counter
  */
 static int
 ProcSyncQueryCounter(ClientPtr client)
 {
     REQUEST(xSyncQueryCounterReq);
     xSyncQueryCounterReply rep;
     SyncCounter *pCounter;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncQueryCounterReq);
 
     rc = dixLookupResourceByType((void **) &pCounter, stuff->counter,
                                  RTCounter, client, DixReadAccess);
     if (rc != Success)
         return rc;
 
     /* if system counter, ask it what the current value is */
     if (IsSystemCounter(pCounter)) {
         (*pCounter->pSysCounterInfo->QueryValue) ((void *) pCounter,
                                                   &pCounter->value);
     }
 
     rep = (xSyncQueryCounterReply) {
         .type = X_Reply,
         .sequenceNumber = client->sequence,
         .length = 0,
         .value_hi = pCounter->value >> 32,
         .value_lo = pCounter->value
     };
 
     if (client->swapped) {
         swaps(&rep.sequenceNumber);
         swapl(&rep.length);
         swapl(&rep.value_hi);
         swapl(&rep.value_lo);
     }
     WriteToClient(client, sizeof(xSyncQueryCounterReply), &rep);
     return Success;
 }
 
 /*
  * ** Create Alarm
  */
 static int
 ProcSyncCreateAlarm(ClientPtr client)
 {
     REQUEST(xSyncCreateAlarmReq);
     SyncAlarm *pAlarm;
     int status;
     unsigned long len, vmask;
     SyncTrigger *pTrigger;
 
     REQUEST_AT_LEAST_SIZE(xSyncCreateAlarmReq);
 
     LEGAL_NEW_RESOURCE(stuff->id, client);
 
     vmask = stuff->valueMask;
     len = client->req_len - bytes_to_int32(sizeof(xSyncCreateAlarmReq));
     /* the "extra" call to Ones accounts for the presence of 64 bit values */
     if (len != (Ones(vmask) + Ones(vmask & (XSyncCAValue | XSyncCADelta))))
         return BadLength;
 
     if (!(pAlarm = malloc(sizeof(SyncAlarm)))) {
         return BadAlloc;
     }
 
     /* set up defaults */
 
     pTrigger = &pAlarm->trigger;
     pTrigger->pSync = NULL;
     pTrigger->value_type = XSyncAbsolute;
     pTrigger->wait_value = 0;
     pTrigger->test_type = XSyncPositiveComparison;
     pTrigger->TriggerFired = SyncAlarmTriggerFired;
     pTrigger->CounterDestroyed = SyncAlarmCounterDestroyed;
     status = SyncInitTrigger(client, pTrigger, None, RTCounter,
                              XSyncCAAllTrigger);
     if (status != Success) {
         free(pAlarm);
         return status;
     }
 
     pAlarm->client = client;
     pAlarm->alarm_id = stuff->id;
     pAlarm->delta = 1;
     pAlarm->events = TRUE;
     pAlarm->state = XSyncAlarmInactive;
     pAlarm->pEventClients = NULL;
     status = SyncChangeAlarmAttributes(client, pAlarm, vmask,
                                        (CARD32 *) &stuff[1]);
     if (status != Success) {
         free(pAlarm);
         return status;
     }
 
     if (!AddResource(stuff->id, RTAlarm, pAlarm))
         return BadAlloc;
 
     /*  see if alarm already triggered.  NULL counter will not trigger
      *  in CreateAlarm and sets alarm state to Inactive.
      */
 
     if (!pTrigger->pSync) {
         pAlarm->state = XSyncAlarmInactive;     /* XXX protocol change */
     }
     else {
         SyncCounter *pCounter;
 
         if (!SyncCheckWarnIsCounter(pTrigger->pSync,
                                     WARN_INVALID_COUNTER_ALARM)) {
             FreeResource(stuff->id, RT_NONE);
             return BadAlloc;
         }
 
         pCounter = (SyncCounter *) pTrigger->pSync;
 
         if ((*pTrigger->CheckTrigger) (pTrigger, pCounter->value))
             (*pTrigger->TriggerFired) (pTrigger);
     }
 
     return Success;
 }
 
 /*
  * ** Change Alarm
  */
 static int
 ProcSyncChangeAlarm(ClientPtr client)
 {
     REQUEST(xSyncChangeAlarmReq);
     SyncAlarm *pAlarm;
     SyncCounter *pCounter = NULL;
     long vmask;
     int len, status;
 
     REQUEST_AT_LEAST_SIZE(xSyncChangeAlarmReq);
 
     status = dixLookupResourceByType((void **) &pAlarm, stuff->alarm, RTAlarm,
                                      client, DixWriteAccess);
     if (status != Success)
         return status;
 
     vmask = stuff->valueMask;
     len = client->req_len - bytes_to_int32(sizeof(xSyncChangeAlarmReq));
     /* the "extra" call to Ones accounts for the presence of 64 bit values */
     if (len != (Ones(vmask) + Ones(vmask & (XSyncCAValue | XSyncCADelta))))
         return BadLength;
 
     if ((status = SyncChangeAlarmAttributes(client, pAlarm, vmask,
                                             (CARD32 *) &stuff[1])) != Success)
         return status;
 
     if (SyncCheckWarnIsCounter(pAlarm->trigger.pSync,
                                WARN_INVALID_COUNTER_ALARM))
         pCounter = (SyncCounter *) pAlarm->trigger.pSync;
 
     /*  see if alarm already triggered.  NULL counter WILL trigger
      *  in ChangeAlarm.
      */
 
     if (!pCounter ||
         (*pAlarm->trigger.CheckTrigger) (&pAlarm->trigger, pCounter->value)) {
         (*pAlarm->trigger.TriggerFired) (&pAlarm->trigger);
     }
     return Success;
 }
 
 static int
 ProcSyncQueryAlarm(ClientPtr client)
 {
     REQUEST(xSyncQueryAlarmReq);
     SyncAlarm *pAlarm;
     xSyncQueryAlarmReply rep;
     SyncTrigger *pTrigger;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncQueryAlarmReq);
 
     rc = dixLookupResourceByType((void **) &pAlarm, stuff->alarm, RTAlarm,
                                  client, DixReadAccess);
     if (rc != Success)
         return rc;
 
     pTrigger = &pAlarm->trigger;
     rep = (xSyncQueryAlarmReply) {
         .type = X_Reply,
         .sequenceNumber = client->sequence,
         .length =
           bytes_to_int32(sizeof(xSyncQueryAlarmReply) - sizeof(xGenericReply)),
         .counter = (pTrigger->pSync) ? pTrigger->pSync->id : None,
 
 #if 0  /* XXX unclear what to do, depends on whether relative value-types
         * are "consumed" immediately and are considered absolute from then
         * on.
         */
         .value_type = pTrigger->value_type,
         .wait_value_hi = pTrigger->wait_value >> 32,
         .wait_value_lo = pTrigger->wait_value,
 #else
         .value_type = XSyncAbsolute,
         .wait_value_hi = pTrigger->test_value >> 32,
         .wait_value_lo = pTrigger->test_value,
 #endif
 
         .test_type = pTrigger->test_type,
         .delta_hi = pAlarm->delta >> 32,
         .delta_lo = pAlarm->delta,
         .events = pAlarm->events,
         .state = pAlarm->state
     };
 
     if (client->swapped) {
         swaps(&rep.sequenceNumber);
         swapl(&rep.length);
         swapl(&rep.counter);
         swapl(&rep.wait_value_hi);
         swapl(&rep.wait_value_lo);
         swapl(&rep.test_type);
         swapl(&rep.delta_hi);
         swapl(&rep.delta_lo);
     }
 
     WriteToClient(client, sizeof(xSyncQueryAlarmReply), &rep);
     return Success;
 }
 
 static int
 ProcSyncDestroyAlarm(ClientPtr client)
 {
     SyncAlarm *pAlarm;
     int rc;
 
     REQUEST(xSyncDestroyAlarmReq);
 
     REQUEST_SIZE_MATCH(xSyncDestroyAlarmReq);
 
     rc = dixLookupResourceByType((void **) &pAlarm, stuff->alarm, RTAlarm,
                                  client, DixDestroyAccess);
     if (rc != Success)
         return rc;
 
     FreeResource(stuff->alarm, RT_NONE);
     return Success;
 }
 
 static int
 ProcSyncCreateFence(ClientPtr client)
 {
     REQUEST(xSyncCreateFenceReq);
     DrawablePtr pDraw;
     SyncFence *pFence;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncCreateFenceReq);
 
     rc = dixLookupDrawable(&pDraw, stuff->d, client, M_ANY, DixGetAttrAccess);
     if (rc != Success)
         return rc;
 
     LEGAL_NEW_RESOURCE(stuff->fid, client);
 
     if (!(pFence = (SyncFence *) SyncCreate(client, stuff->fid, SYNC_FENCE)))
         return BadAlloc;
 
     miSyncInitFence(pDraw->pScreen, pFence, stuff->initially_triggered);
 
     return Success;
 }
 
 static int
 FreeFence(void *obj, XID id)
 {
     SyncFence *pFence = (SyncFence *) obj;
 
     miSyncDestroyFence(pFence);
 
     return Success;
 }
 
 int
 SyncVerifyFence(SyncFence ** ppSyncFence, XID fid, ClientPtr client, Mask mode)
 {
     int rc = dixLookupResourceByType((void **) ppSyncFence, fid, RTFence,
                                      client, mode);
 
     if (rc != Success)
         client->errorValue = fid;
 
     return rc;
 }
 
 static int
 ProcSyncTriggerFence(ClientPtr client)
 {
     REQUEST(xSyncTriggerFenceReq);
     SyncFence *pFence;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncTriggerFenceReq);
 
     rc = dixLookupResourceByType((void **) &pFence, stuff->fid, RTFence,
                                  client, DixWriteAccess);
     if (rc != Success)
         return rc;
 
     miSyncTriggerFence(pFence);
 
     return Success;
 }
 
 static int
 ProcSyncResetFence(ClientPtr client)
 {
     REQUEST(xSyncResetFenceReq);
     SyncFence *pFence;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncResetFenceReq);
 
     rc = dixLookupResourceByType((void **) &pFence, stuff->fid, RTFence,
                                  client, DixWriteAccess);
     if (rc != Success)
         return rc;
 
     if (pFence->funcs.CheckTriggered(pFence) != TRUE)
         return BadMatch;
 
     pFence->funcs.Reset(pFence);
 
     return Success;
 }
 
 static int
 ProcSyncDestroyFence(ClientPtr client)
 {
     REQUEST(xSyncDestroyFenceReq);
     SyncFence *pFence;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncDestroyFenceReq);
 
     rc = dixLookupResourceByType((void **) &pFence, stuff->fid, RTFence,
                                  client, DixDestroyAccess);
     if (rc != Success)
         return rc;
 
     FreeResource(stuff->fid, RT_NONE);
     return Success;
 }
 
 static int
 ProcSyncQueryFence(ClientPtr client)
 {
     REQUEST(xSyncQueryFenceReq);
     xSyncQueryFenceReply rep;
     SyncFence *pFence;
     int rc;
 
     REQUEST_SIZE_MATCH(xSyncQueryFenceReq);
 
     rc = dixLookupResourceByType((void **) &pFence, stuff->fid,
                                  RTFence, client, DixReadAccess);
     if (rc != Success)
         return rc;
 
     rep = (xSyncQueryFenceReply) {
         .type = X_Reply,
         .sequenceNumber = client->sequence,
         .length = 0,
 
         .triggered = pFence->funcs.CheckTriggered(pFence)
     };
 
     if (client->swapped) {
         swaps(&rep.sequenceNumber);
         swapl(&rep.length);
     }
 
     WriteToClient(client, sizeof(xSyncQueryFenceReply), &rep);
     return Success;
 }
 
 static int
 ProcSyncAwaitFence(ClientPtr client)
 {
     REQUEST(xSyncAwaitFenceReq);
     SyncAwaitUnion *pAwaitUnion;
     SyncAwait *pAwait;
 
     /* Use CARD32 rather than XSyncFence because XIDs are hard-coded to
      * CARD32 in protocol definitions */
     CARD32 *pProtocolFences;
     int status;
     int len;
     int items;
     int i;
 
     REQUEST_AT_LEAST_SIZE(xSyncAwaitFenceReq);
 
     len = client->req_len << 2;
     len -= sz_xSyncAwaitFenceReq;
     items = len / sizeof(CARD32);
 
     if (items * sizeof(CARD32) != len) {
         return BadLength;
     }
     if (items == 0) {
         client->errorValue = items;
         return BadValue;
     }
 
     if (!(pAwaitUnion = SyncAwaitPrologue(client, items)))
         return BadAlloc;
 
     /* don't need to do any more memory allocation for this request! */
 
     pProtocolFences = (CARD32 *) &stuff[1];
 
     pAwait = &(pAwaitUnion + 1)->await; /* skip over header */
     for (i = 0; i < items; i++, pProtocolFences++, pAwait++) {
         if (*pProtocolFences == None) {
             /*  this should take care of removing any triggers created by
              *  this request that have already been registered on sync objects
              */
             FreeResource(pAwaitUnion->header.delete_id, RT_NONE);
             client->errorValue = *pProtocolFences;
             return SyncErrorBase + XSyncBadFence;
         }
 
         pAwait->trigger.pSync = NULL;
         /* Provide acceptable values for these unused fields to
          * satisfy SyncInitTrigger's validation logic
          */
         pAwait->trigger.value_type = XSyncAbsolute;
         pAwait->trigger.wait_value = 0;
         pAwait->trigger.test_type = 0;
 
         status = SyncInitTrigger(client, &pAwait->trigger,
                                  *pProtocolFences, RTFence, XSyncCAAllTrigger);
         if (status != Success) {
             /*  this should take care of removing any triggers created by
              *  this request that have already been registered on sync objects
              */
             FreeResource(pAwaitUnion->header.delete_id, RT_NONE);
             return status;
         }
         /* this is not a mistake -- same function works for both cases */
         pAwait->trigger.TriggerFired = SyncAwaitTriggerFired;
         pAwait->trigger.CounterDestroyed = SyncAwaitTriggerFired;
         /* event_threshold is unused for fence syncs */
         pAwait->event_threshold = 0;
         pAwait->pHeader = &pAwaitUnion->header;
         pAwaitUnion->header.num_waitconditions++;
     }
 
     SyncAwaitEpilogue(client, items, pAwaitUnion);
 
     return Success;
 }
 
 /*
  * ** Given an extension request, call the appropriate request procedure
  */
 static int
 ProcSyncDispatch(ClientPtr client)
 {
     REQUEST(xReq);
 
     switch (stuff->data) {
     case X_SyncInitialize:
         return ProcSyncInitialize(client);
     case X_SyncListSystemCounters:
         return ProcSyncListSystemCounters(client);
     case X_SyncCreateCounter:
         return ProcSyncCreateCounter(client);
     case X_SyncSetCounter:
         return ProcSyncSetCounter(client);
     case X_SyncChangeCounter:
         return ProcSyncChangeCounter(client);
     case X_SyncQueryCounter:
         return ProcSyncQueryCounter(client);
     case X_SyncDestroyCounter:
         return ProcSyncDestroyCounter(client);
     case X_SyncAwait:
         return ProcSyncAwait(client);
     case X_SyncCreateAlarm:
         return ProcSyncCreateAlarm(client);
     case X_SyncChangeAlarm:
         return ProcSyncChangeAlarm(client);
     case X_SyncQueryAlarm:
         return ProcSyncQueryAlarm(client);
     case X_SyncDestroyAlarm:
         return ProcSyncDestroyAlarm(client);
     case X_SyncSetPriority:
         return ProcSyncSetPriority(client);
     case X_SyncGetPriority:
         return ProcSyncGetPriority(client);
     case X_SyncCreateFence:
         return ProcSyncCreateFence(client);
     case X_SyncTriggerFence:
         return ProcSyncTriggerFence(client);
     case X_SyncResetFence:
         return ProcSyncResetFence(client);
     case X_SyncDestroyFence:
         return ProcSyncDestroyFence(client);
     case X_SyncQueryFence:
         return ProcSyncQueryFence(client);
     case X_SyncAwaitFence:
         return ProcSyncAwaitFence(client);
     default:
         return BadRequest;
     }
 }
 
 /*
  * Boring Swapping stuff ...
  */
 
 static int _X_COLD
 SProcSyncInitialize(ClientPtr client)
 {
     REQUEST(xSyncInitializeReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncInitializeReq);
 
     return ProcSyncInitialize(client);
 }
 
 static int _X_COLD
 SProcSyncListSystemCounters(ClientPtr client)
 {
     REQUEST(xSyncListSystemCountersReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncListSystemCountersReq);
 
     return ProcSyncListSystemCounters(client);
 }
 
 static int _X_COLD
 SProcSyncCreateCounter(ClientPtr client)
 {
     REQUEST(xSyncCreateCounterReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncCreateCounterReq);
     swapl(&stuff->cid);
     swapl(&stuff->initial_value_lo);
     swapl(&stuff->initial_value_hi);
 
     return ProcSyncCreateCounter(client);
 }
 
 static int _X_COLD
 SProcSyncSetCounter(ClientPtr client)
 {
     REQUEST(xSyncSetCounterReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncSetCounterReq);
     swapl(&stuff->cid);
     swapl(&stuff->value_lo);
     swapl(&stuff->value_hi);
 
     return ProcSyncSetCounter(client);
 }
 
 static int _X_COLD
 SProcSyncChangeCounter(ClientPtr client)
 {
     REQUEST(xSyncChangeCounterReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncChangeCounterReq);
     swapl(&stuff->cid);
     swapl(&stuff->value_lo);
     swapl(&stuff->value_hi);
 
     return ProcSyncChangeCounter(client);
 }
 
 static int _X_COLD
 SProcSyncQueryCounter(ClientPtr client)
 {
     REQUEST(xSyncQueryCounterReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncQueryCounterReq);
     swapl(&stuff->counter);
 
     return ProcSyncQueryCounter(client);
 }
 
 static int _X_COLD
 SProcSyncDestroyCounter(ClientPtr client)
 {
     REQUEST(xSyncDestroyCounterReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncDestroyCounterReq);
     swapl(&stuff->counter);
 
     return ProcSyncDestroyCounter(client);
 }
 
 static int _X_COLD
 SProcSyncAwait(ClientPtr client)
 {
     REQUEST(xSyncAwaitReq);
     swaps(&stuff->length);
     REQUEST_AT_LEAST_SIZE(xSyncAwaitReq);
     SwapRestL(stuff);
 
     return ProcSyncAwait(client);
 }
 
 static int _X_COLD
 SProcSyncCreateAlarm(ClientPtr client)
 {
     REQUEST(xSyncCreateAlarmReq);
     swaps(&stuff->length);
     REQUEST_AT_LEAST_SIZE(xSyncCreateAlarmReq);
     swapl(&stuff->id);
     swapl(&stuff->valueMask);
     SwapRestL(stuff);
 
     return ProcSyncCreateAlarm(client);
 }
 
 static int _X_COLD
 SProcSyncChangeAlarm(ClientPtr client)
 {
     REQUEST(xSyncChangeAlarmReq);
     swaps(&stuff->length);
     REQUEST_AT_LEAST_SIZE(xSyncChangeAlarmReq);
     swapl(&stuff->alarm);
     swapl(&stuff->valueMask);
     SwapRestL(stuff);
     return ProcSyncChangeAlarm(client);
 }
 
 static int _X_COLD
 SProcSyncQueryAlarm(ClientPtr client)
 {
     REQUEST(xSyncQueryAlarmReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncQueryAlarmReq);
     swapl(&stuff->alarm);
 
     return ProcSyncQueryAlarm(client);
 }
 
 static int _X_COLD
 SProcSyncDestroyAlarm(ClientPtr client)
 {
     REQUEST(xSyncDestroyAlarmReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncDestroyAlarmReq);
     swapl(&stuff->alarm);
 
     return ProcSyncDestroyAlarm(client);
 }
 
 static int _X_COLD
 SProcSyncSetPriority(ClientPtr client)
 {
     REQUEST(xSyncSetPriorityReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncSetPriorityReq);
     swapl(&stuff->id);
     swapl(&stuff->priority);
 
     return ProcSyncSetPriority(client);
 }
 
 static int _X_COLD
 SProcSyncGetPriority(ClientPtr client)
 {
     REQUEST(xSyncGetPriorityReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncGetPriorityReq);
     swapl(&stuff->id);
 
     return ProcSyncGetPriority(client);
 }
 
 static int _X_COLD
 SProcSyncCreateFence(ClientPtr client)
 {
     REQUEST(xSyncCreateFenceReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncCreateFenceReq);
     swapl(&stuff->fid);
 
     return ProcSyncCreateFence(client);
 }
 
 static int _X_COLD
 SProcSyncTriggerFence(ClientPtr client)
 {
     REQUEST(xSyncTriggerFenceReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncTriggerFenceReq);
     swapl(&stuff->fid);
 
     return ProcSyncTriggerFence(client);
 }
 
 static int _X_COLD
 SProcSyncResetFence(ClientPtr client)
 {
     REQUEST(xSyncResetFenceReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncResetFenceReq);
     swapl(&stuff->fid);
 
     return ProcSyncResetFence(client);
 }
 
 static int _X_COLD
 SProcSyncDestroyFence(ClientPtr client)
 {
     REQUEST(xSyncDestroyFenceReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncDestroyFenceReq);
     swapl(&stuff->fid);
 
     return ProcSyncDestroyFence(client);
 }
 
 static int _X_COLD
 SProcSyncQueryFence(ClientPtr client)
 {
     REQUEST(xSyncQueryFenceReq);
     swaps(&stuff->length);
     REQUEST_SIZE_MATCH(xSyncQueryFenceReq);
     swapl(&stuff->fid);
 
     return ProcSyncQueryFence(client);
 }
 
 static int _X_COLD
 SProcSyncAwaitFence(ClientPtr client)
 {
     REQUEST(xSyncAwaitFenceReq);
     swaps(&stuff->length);
     REQUEST_AT_LEAST_SIZE(xSyncAwaitFenceReq);
     SwapRestL(stuff);
 
     return ProcSyncAwaitFence(client);
 }
 
 static int _X_COLD
 SProcSyncDispatch(ClientPtr client)
 {
     REQUEST(xReq);
 
     switch (stuff->data) {
     case X_SyncInitialize:
         return SProcSyncInitialize(client);
     case X_SyncListSystemCounters:
         return SProcSyncListSystemCounters(client);
     case X_SyncCreateCounter:
         return SProcSyncCreateCounter(client);
     case X_SyncSetCounter:
         return SProcSyncSetCounter(client);
     case X_SyncChangeCounter:
         return SProcSyncChangeCounter(client);
     case X_SyncQueryCounter:
         return SProcSyncQueryCounter(client);
     case X_SyncDestroyCounter:
         return SProcSyncDestroyCounter(client);
     case X_SyncAwait:
         return SProcSyncAwait(client);
     case X_SyncCreateAlarm:
         return SProcSyncCreateAlarm(client);
     case X_SyncChangeAlarm:
         return SProcSyncChangeAlarm(client);
     case X_SyncQueryAlarm:
         return SProcSyncQueryAlarm(client);
     case X_SyncDestroyAlarm:
         return SProcSyncDestroyAlarm(client);
     case X_SyncSetPriority:
         return SProcSyncSetPriority(client);
     case X_SyncGetPriority:
         return SProcSyncGetPriority(client);
     case X_SyncCreateFence:
         return SProcSyncCreateFence(client);
     case X_SyncTriggerFence:
         return SProcSyncTriggerFence(client);
     case X_SyncResetFence:
         return SProcSyncResetFence(client);
     case X_SyncDestroyFence:
         return SProcSyncDestroyFence(client);
     case X_SyncQueryFence:
         return SProcSyncQueryFence(client);
     case X_SyncAwaitFence:
         return SProcSyncAwaitFence(client);
     default:
         return BadRequest;
     }
 }
 
 /*
  * Event Swapping
  */
 
 static void _X_COLD
 SCounterNotifyEvent(xSyncCounterNotifyEvent * from,
                     xSyncCounterNotifyEvent * to)
 {
     to->type = from->type;
     to->kind = from->kind;
     cpswaps(from->sequenceNumber, to->sequenceNumber);
     cpswapl(from->counter, to->counter);
     cpswapl(from->wait_value_lo, to->wait_value_lo);
     cpswapl(from->wait_value_hi, to->wait_value_hi);
     cpswapl(from->counter_value_lo, to->counter_value_lo);
     cpswapl(from->counter_value_hi, to->counter_value_hi);
     cpswapl(from->time, to->time);
     cpswaps(from->count, to->count);
     to->destroyed = from->destroyed;
 }
 
 static void _X_COLD
 SAlarmNotifyEvent(xSyncAlarmNotifyEvent * from, xSyncAlarmNotifyEvent * to)
 {
     to->type = from->type;
     to->kind = from->kind;
     cpswaps(from->sequenceNumber, to->sequenceNumber);
     cpswapl(from->alarm, to->alarm);
     cpswapl(from->counter_value_lo, to->counter_value_lo);
     cpswapl(from->counter_value_hi, to->counter_value_hi);
     cpswapl(from->alarm_value_lo, to->alarm_value_lo);
     cpswapl(from->alarm_value_hi, to->alarm_value_hi);
     cpswapl(from->time, to->time);
     to->state = from->state;
 }
 
 /*
  * ** Close everything down. ** This is fairly simple for now.
  */
 /* ARGSUSED */
 static void
 SyncResetProc(ExtensionEntry * extEntry)
 {
     RTCounter = 0;
 }
 
 /*
  * ** Initialise the extension.
  */
 void
 SyncExtensionInit(void)
 {
     ExtensionEntry *extEntry;
     int s;
 
     for (s = 0; s < screenInfo.numScreens; s++)
         miSyncSetup(screenInfo.screens[s]);
 
     RTCounter = CreateNewResourceType(FreeCounter, "SyncCounter");
     xorg_list_init(&SysCounterList);
     RTAlarm = CreateNewResourceType(FreeAlarm, "SyncAlarm");
     RTAwait = CreateNewResourceType(FreeAwait, "SyncAwait");
     RTFence = CreateNewResourceType(FreeFence, "SyncFence");
     if (RTAwait)
         RTAwait |= RC_NEVERRETAIN;
     RTAlarmClient = CreateNewResourceType(FreeAlarmClient, "SyncAlarmClient");
     if (RTAlarmClient)
         RTAlarmClient |= RC_NEVERRETAIN;
 
     if (RTCounter == 0 || RTAwait == 0 || RTAlarm == 0 ||
         RTAlarmClient == 0 ||
         (extEntry = AddExtension(SYNC_NAME,
                                  XSyncNumberEvents, XSyncNumberErrors,
                                  ProcSyncDispatch, SProcSyncDispatch,
                                  SyncResetProc, StandardMinorOpcode)) == NULL) {
         ErrorF("Sync Extension %d.%d failed to Initialise\n",
                SYNC_MAJOR_VERSION, SYNC_MINOR_VERSION);
         return;
     }
 
     SyncEventBase = extEntry->eventBase;
     SyncErrorBase = extEntry->errorBase;
     EventSwapVector[SyncEventBase + XSyncCounterNotify] =
         (EventSwapPtr) SCounterNotifyEvent;
     EventSwapVector[SyncEventBase + XSyncAlarmNotify] =
         (EventSwapPtr) SAlarmNotifyEvent;
 
     SetResourceTypeErrorValue(RTCounter, SyncErrorBase + XSyncBadCounter);
     SetResourceTypeErrorValue(RTAlarm, SyncErrorBase + XSyncBadAlarm);
     SetResourceTypeErrorValue(RTFence, SyncErrorBase + XSyncBadFence);
 
     /*
      * Although SERVERTIME is implemented by the OS layer, we initialise it
      * here because doing it in OsInit() is too early. The resource database
      * is not initialised when OsInit() is called. This is just about OK
      * because there is always a servertime counter.
      */
     SyncInitServerTime();
     SyncInitIdleTime();
 
 #ifdef DEBUG
     fprintf(stderr, "Sync Extension %d.%d\n",
             SYNC_MAJOR_VERSION, SYNC_MINOR_VERSION);
 #endif
 }
 
 /*
  * ***** SERVERTIME implementation - should go in its own file in OS directory?
  */
 
 static void *ServertimeCounter;
 static int64_t Now;
 static int64_t *pnext_time;
 
 static void GetTime(void)
 {
     unsigned long millis = GetTimeInMillis();
     unsigned long maxis = Now >> 32;
 
     if (millis < (Now & 0xffffffff))
         maxis++;
 
     Now = ((int64_t)maxis << 32) | millis;
 }
 
 /*
 *** Server Block Handler
 *** code inspired by multibuffer extension (now deprecated)
  */
 /*ARGSUSED*/ static void
 ServertimeBlockHandler(void *env, void *wt)
 {
     unsigned long timeout;
 
     if (pnext_time) {
         GetTime();
 
         if (Now >= *pnext_time) {
             timeout = 0;
         }
         else {
             timeout = *pnext_time - Now;
         }
         AdjustWaitForDelay(wt, timeout);        /* os/utils.c */
     }
 }
 
 /*
 *** Wakeup Handler
  */
 /*ARGSUSED*/ static void
 ServertimeWakeupHandler(void *env, int rc)
 {
     if (pnext_time) {
         GetTime();
 
         if (Now >= *pnext_time) {
             SyncChangeCounter(ServertimeCounter, Now);
         }
     }
 }
 
 static void
 ServertimeQueryValue(void *pCounter, int64_t *pValue_return)
 {
     GetTime();
     *pValue_return = Now;
 }
 
 static void
 ServertimeBracketValues(void *pCounter, int64_t *pbracket_less,
                         int64_t *pbracket_greater)
 {
     if (!pnext_time && pbracket_greater) {
         RegisterBlockAndWakeupHandlers(ServertimeBlockHandler,
                                        ServertimeWakeupHandler, NULL);
     }
     else if (pnext_time && !pbracket_greater) {
         RemoveBlockAndWakeupHandlers(ServertimeBlockHandler,
                                      ServertimeWakeupHandler, NULL);
     }
     pnext_time = pbracket_greater;
 }
 
 static void
 SyncInitServerTime(void)
 {
     int64_t resolution = 4;
 
     Now = GetTimeInMillis();
     ServertimeCounter = SyncCreateSystemCounter("SERVERTIME", Now, resolution,
                                                 XSyncCounterNeverDecreases,
                                                 ServertimeQueryValue,
                                                 ServertimeBracketValues);
     pnext_time = NULL;
 }
 
 /*
  * IDLETIME implementation
  */
 
 typedef struct {
     int64_t *value_less;
     int64_t *value_greater;
     int deviceid;
 } IdleCounterPriv;
 
 static void
 IdleTimeQueryValue(void *pCounter, int64_t *pValue_return)
 {
     int deviceid;
     CARD32 idle;
 
     if (pCounter) {
         SyncCounter *counter = pCounter;
         IdleCounterPriv *priv = SysCounterGetPrivate(counter);
         deviceid = priv->deviceid;
     }
     else
         deviceid = XIAllDevices;
     idle = GetTimeInMillis() - LastEventTime(deviceid).milliseconds;
     *pValue_return = idle;
 }
 
 static void
 IdleTimeBlockHandler(void *pCounter, void *wt)
 {
     SyncCounter *counter = pCounter;
     IdleCounterPriv *priv = SysCounterGetPrivate(counter);
     int64_t *less = priv->value_less;
     int64_t *greater = priv->value_greater;
     int64_t idle, old_idle;
     SyncTriggerList *list = counter->sync.pTriglist;
     SyncTrigger *trig;
 
     if (!less && !greater)
         return;
 
     old_idle = counter->value;
     IdleTimeQueryValue(counter, &idle);
     counter->value = idle;      /* push, so CheckTrigger works */
 
     /**
      * There's an indefinite amount of time between ProcessInputEvents()
      * where the idle time is reset and the time we actually get here. idle
      * may be past the lower bracket if we dawdled with the events, so
      * check for whether we did reset and bomb out of select immediately.
      */
     if (less && idle > *less &&
         LastEventTimeWasReset(priv->deviceid)) {
         AdjustWaitForDelay(wt, 0);
     } else if (less && idle <= *less) {
         /*
          * We've been idle for less than the threshold value, and someone
          * wants to know about that, but now we need to know whether they
          * want level or edge trigger.  Check the trigger list against the
          * current idle time, and if any succeed, bomb out of select()
          * immediately so we can reschedule.
          */
 
         for (list = counter->sync.pTriglist; list; list = list->next) {
             trig = list->pTrigger;
             if (trig->CheckTrigger(trig, old_idle)) {
                 AdjustWaitForDelay(wt, 0);
                 break;
             }
         }
         /*
          * We've been called exactly on the idle time, but we have a
          * NegativeTransition trigger which requires a transition from an
          * idle time greater than this.  Schedule a wakeup for the next
          * millisecond so we won't miss a transition.
          */
         if (idle == *less)
             AdjustWaitForDelay(wt, 1);
     }
     else if (greater) {
         /*
          * There's a threshold in the positive direction.  If we've been
          * idle less than it, schedule a wakeup for sometime in the future.
          * If we've been idle more than it, and someone wants to know about
          * that level-triggered, schedule an immediate wakeup.
          */
 
         if (idle < *greater) {
             AdjustWaitForDelay(wt, *greater - idle);
         }
         else {
             for (list = counter->sync.pTriglist; list;
                  list = list->next) {
                 trig = list->pTrigger;
                 if (trig->CheckTrigger(trig, old_idle)) {
                     AdjustWaitForDelay(wt, 0);
                     break;
                 }
             }
         }
     }
 
     counter->value = old_idle;  /* pop */
 }
 
 static void
 IdleTimeCheckBrackets(SyncCounter *counter, int64_t idle,
                       int64_t *less, int64_t *greater)
 {
     if ((greater && idle >= *greater) ||
         (less && idle <= *less)) {
         SyncChangeCounter(counter, idle);
     }
     else
         SyncUpdateCounter(counter, idle);
 }
 
 static void
 IdleTimeWakeupHandler(void *pCounter, int rc)
 {
     SyncCounter *counter = pCounter;
     IdleCounterPriv *priv = SysCounterGetPrivate(counter);
     int64_t *less = priv->value_less;
     int64_t *greater = priv->value_greater;
     int64_t idle;
 
     if (!less && !greater)
         return;
 
     IdleTimeQueryValue(pCounter, &idle);
 
     /*
       There is no guarantee for the WakeupHandler to be called within a specific
       timeframe. Idletime may go to 0, but by the time we get here, it may be
       non-zero and alarms for a pos. transition on 0 won't get triggered.
       https://bugs.freedesktop.org/show_bug.cgi?id=70476
       */
     if (LastEventTimeWasReset(priv->deviceid)) {
         LastEventTimeToggleResetFlag(priv->deviceid, FALSE);
         if (idle != 0) {
             IdleTimeCheckBrackets(counter, 0, less, greater);
             less = priv->value_less;
             greater = priv->value_greater;
         }
     }
 
     IdleTimeCheckBrackets(counter, idle, less, greater);
 }
 
 static void
 IdleTimeBracketValues(void *pCounter, int64_t *pbracket_less,
                       int64_t *pbracket_greater)
 {
     SyncCounter *counter = pCounter;
     IdleCounterPriv *priv = SysCounterGetPrivate(counter);
     int64_t *less = priv->value_less;
     int64_t *greater = priv->value_greater;
     Bool registered = (less || greater);
 
     if (registered && !pbracket_less && !pbracket_greater) {
         RemoveBlockAndWakeupHandlers(IdleTimeBlockHandler,
                                      IdleTimeWakeupHandler, pCounter);
     }
     else if (!registered && (pbracket_less || pbracket_greater)) {
         /* Reset flag must be zero so we don't force a idle timer reset on
            the first wakeup */
         LastEventTimeToggleResetAll(FALSE);
         RegisterBlockAndWakeupHandlers(IdleTimeBlockHandler,
                                        IdleTimeWakeupHandler, pCounter);
     }
 
     priv->value_greater = pbracket_greater;
     priv->value_less = pbracket_less;
 }
 
 static SyncCounter*
 init_system_idle_counter(const char *name, int deviceid)
 {
     int64_t resolution = 4;
     int64_t idle;
     SyncCounter *idle_time_counter;
 
     IdleTimeQueryValue(NULL, &idle);
 
     idle_time_counter = SyncCreateSystemCounter(name, idle, resolution,
                                                 XSyncCounterUnrestricted,
                                                 IdleTimeQueryValue,
                                                 IdleTimeBracketValues);
 
     if (idle_time_counter != NULL) {
         IdleCounterPriv *priv = malloc(sizeof(IdleCounterPriv));
 
         priv->value_less = priv->value_greater = NULL;
         priv->deviceid = deviceid;
 
         idle_time_counter->pSysCounterInfo->private = priv;
     }
 
     return idle_time_counter;
 }
 
 static void
 SyncInitIdleTime(void)
 {
     init_system_idle_counter("IDLETIME", XIAllDevices);
 }
 
 SyncCounter*
 SyncInitDeviceIdleTime(DeviceIntPtr dev)
 {
     char timer_name[64];
     sprintf(timer_name, "DEVICEIDLETIME %d", dev->id);
 
     return init_system_idle_counter(timer_name, dev->id);
 }
 
 void SyncRemoveDeviceIdleTime(SyncCounter *counter)
 {
     /* FreeAllResources() frees all system counters before the devices are
        shut down, check if there are any left before freeing the device's
        counter */
     if (counter && !xorg_list_is_empty(&SysCounterList))
         xorg_list_del(&counter->pSysCounterInfo->entry);
 }