dix: resize EQ to minimum size to avoid reallocs during SIGIO.

When a new device is added, calculate the event size needed if a DCCE event is
sent and set the EQ's event size to this minimum. This avoids reallocs when a
event is sent (which may happen during a SIGIO).

dix/devices.c

@@ -249,6 +249,7 @@ EnableDevice(DeviceIntPtr dev)
     listlen = GetEventList(&evlist);
     OsBlockSignals();
     SetMinimumEventSize(evlist, listlen, evsize);
+    mieqResizeEvents(evsize);
     OsReleaseSignals();
 
     if ((*prev != dev) || !dev->inited ||

mi/mi.h

@@ -153,6 +153,10 @@ extern Bool mieqInit(
     void
 );
 
+extern void mieqResize(
+    int /* min_size */
+);
+
 extern void mieqEnqueue(
     DeviceIntPtr /*pDev*/,
     xEventPtr /*e*/

mi/mieq.c

@@ -102,6 +102,16 @@ mieqInit(void)
     return TRUE;
 }
 
+/* Ensure all events in the EQ are at least size bytes. */
+Bool
+mieqResizeEvents(int min_size)
+{
+    int i;
+
+    for (i = 0; i < QUEUE_SIZE; i++)
+        SetMinimumEventSize(miEventQueue.events[i].events, 7, min_size);
+}
+
 /*
  * Must be reentrant with ProcessInputEvents.  Assumption: mieqEnqueue
  * will never be interrupted.  If this is called from both signal