diff --git a/Xi/exevents.c b/Xi/exevents.c
index 53db03629..20495e74d 100644
--- a/Xi/exevents.c
+++ b/Xi/exevents.c
@@ -1628,6 +1628,19 @@ SelectForWindow(DeviceIntPtr dev, WindowPtr pWin, ClientPtr client,
     return Success;
 }
 
+static void
+FreeInputClient(InputClientsPtr *other)
+{
+    free(*other);
+    *other = NULL;
+}
+
+static InputClientsPtr
+AllocInputClient(void)
+{
+    return calloc(1, sizeof(InputClients));
+}
+
 int
 AddExtensionClient(WindowPtr pWin, ClientPtr client, Mask mask, int mskidx)
 {
@@ -1635,7 +1648,7 @@ AddExtensionClient(WindowPtr pWin, ClientPtr client, Mask mask, int mskidx)
 
     if (!pWin->optional && !MakeWindowOptional(pWin))
 	return BadAlloc;
-    others = calloc(1, sizeof(InputClients));
+    others = AllocInputClient();
     if (!others)
 	return BadAlloc;
     if (!pWin->optional->inputMasks && !MakeInputMasks(pWin))
@@ -1649,7 +1662,7 @@ AddExtensionClient(WindowPtr pWin, ClientPtr client, Mask mask, int mskidx)
     return Success;
 
 bail:
-    free(others);
+    FreeInputClient(&others);
     return BadAlloc;
 }
 
@@ -1665,6 +1678,13 @@ MakeInputMasks(WindowPtr pWin)
     return TRUE;
 }
 
+static void
+FreeInputMask(OtherInputMasks **imask)
+{
+    free(*imask);
+    *imask = NULL;
+}
+
 void
 RecalculateDeviceDeliverableEvents(WindowPtr pWin)
 {
@@ -1721,14 +1741,15 @@ InputClientGone(WindowPtr pWin, XID id)
 	if (other->resource == id) {
 	    if (prev) {
 		prev->next = other->next;
-		free(other);
+		FreeInputClient(&other);
 	    } else if (!(other->next)) {
 		if (ShouldFreeInputMasks(pWin, TRUE)) {
-		    wOtherInputMasks(pWin)->inputClients = other->next;
-		    free(wOtherInputMasks(pWin));
+		    OtherInputMasks *mask = wOtherInputMasks(pWin);
+		    mask->inputClients = other->next;
+		    FreeInputMask(&mask);
 		    pWin->optional->inputMasks = (OtherInputMasks *) NULL;
 		    CheckWindowOptionalNeed(pWin);
-		    free(other);
+		    FreeInputClient(&other);
 		} else {
 		    other->resource = FakeClientID(0);
 		    if (!AddResource(other->resource, RT_INPUTCLIENT,
@@ -1737,7 +1758,7 @@ InputClientGone(WindowPtr pWin, XID id)
 		}
 	    } else {
 		wOtherInputMasks(pWin)->inputClients = other->next;
-		free(other);
+		FreeInputClient(&other);
 	    }
 	    RecalculateDeviceDeliverableEvents(pWin);
 	    return Success;
diff --git a/Xi/xipassivegrab.c b/Xi/xipassivegrab.c
index 6be27f3d1..2f13a95e8 100644
--- a/Xi/xipassivegrab.c
+++ b/Xi/xipassivegrab.c
@@ -80,7 +80,6 @@ ProcXIPassiveGrabDevice(ClientPtr client)
     DeviceIntPtr dev, mod_dev;
     xXIPassiveGrabDeviceReply rep;
     int i, ret = Success;
-    uint8_t status;
     uint32_t *modifiers;
     xXIGrabModifierInfo *modifiers_failed;
     GrabMask mask;
@@ -145,32 +144,36 @@ ProcXIPassiveGrabDevice(ClientPtr client)
 
     if (stuff->cursor != None)
     {
-        status = dixLookupResourceByType(&tmp, stuff->cursor,
-                                         RT_CURSOR, client, DixUseAccess);
-	if (status != Success)
-	{
-	    client->errorValue = stuff->cursor;
-	    return status;
-	}
+        ret = dixLookupResourceByType(&tmp, stuff->cursor,
+                                      RT_CURSOR, client, DixUseAccess);
+        if (ret != Success)
+        {
+            client->errorValue = stuff->cursor;
+            goto out;
+        }
     }
 
-    status = dixLookupWindow((WindowPtr*)&tmp, stuff->grab_window, client, DixSetAttrAccess);
-    if (status != Success)
-	return status;
+    ret = dixLookupWindow((WindowPtr*)&tmp, stuff->grab_window, client, DixSetAttrAccess);
+    if (ret != Success)
+        goto out;
 
-    status = CheckGrabValues(client, &param);
-    if (status != Success)
-        return status;
+    ret = CheckGrabValues(client, &param);
+    if (ret != Success)
+        goto out;
 
     modifiers = (uint32_t*)&stuff[1] + stuff->mask_len;
     modifiers_failed = calloc(stuff->num_modifiers, sizeof(xXIGrabModifierInfo));
-    if (!modifiers_failed)
-        return BadAlloc;
+    if (!modifiers_failed) {
+        ret = BadAlloc;
+        goto out;
+    }
 
     mod_dev = (IsFloating(dev)) ? dev : GetMaster(dev, MASTER_KEYBOARD);
 
     for (i = 0; i < stuff->num_modifiers; i++, modifiers++)
     {
+        uint8_t status = Success;
+
         param.modifiers = *modifiers;
         switch(stuff->grab_type)
         {
@@ -208,6 +211,7 @@ ProcXIPassiveGrabDevice(ClientPtr client)
         WriteToClient(client, rep.length * 4, (char*)modifiers_failed);
 
     free(modifiers_failed);
+out:
     return ret;
 }
 
diff --git a/dix/events.c b/dix/events.c
index 5e0dc5f17..4847db005 100644
--- a/dix/events.c
+++ b/dix/events.c
@@ -469,10 +469,11 @@ GetXI2MaskByte(unsigned char xi2mask[][XI2MASKSIZE], DeviceIntPtr dev, int event
 
 
 /**
- * Return the windows complete XI2 mask for the given XI2 event type.
+ * @return TRUE if the mask is set for this event from this device on the
+ * window, or FALSE otherwise.
  */
-Mask
-GetWindowXI2Mask(DeviceIntPtr dev, WindowPtr win, xEvent* ev)
+Bool
+WindowXI2MaskIsset(DeviceIntPtr dev, WindowPtr win, xEvent* ev)
 {
     OtherInputMasks *inputMasks = wOtherInputMasks(win);
     int filter;
@@ -484,7 +485,7 @@ GetWindowXI2Mask(DeviceIntPtr dev, WindowPtr win, xEvent* ev)
     evtype = ((xGenericEvent*)ev)->evtype;
     filter = GetEventFilter(dev, ev);
 
-    return (GetXI2MaskByte(inputMasks->xi2mask, dev, evtype) & filter);
+    return !!(GetXI2MaskByte(inputMasks->xi2mask, dev, evtype) & filter);
 }
 
 Mask
@@ -2075,7 +2076,7 @@ GetClientsForDelivery(DeviceIntPtr dev, WindowPtr win,
     {
         OtherInputMasks *inputMasks = wOtherInputMasks(win);
         /* Has any client selected for the event? */
-        if (!GetWindowXI2Mask(dev, win, events))
+        if (!WindowXI2MaskIsset(dev, win, events))
             goto out;
         *clients = inputMasks->inputClients;
     } else {
@@ -3787,14 +3788,13 @@ CheckPassiveGrabsOnWindow(
         }
 
         if (!activate)
-        {
-            return grab;
-        }
+            break;
         else if (!GetXIType(event) && !GetCoreType(event))
         {
             ErrorF("Event type %d in CheckPassiveGrabsOnWindow is neither"
                    " XI 1.x nor core\n", event->any.type);
-            return NULL;
+            grab = NULL;
+            break;
         }
 
         /* The only consumers of corestate are Xi 1.x and core events, which
@@ -3860,9 +3860,10 @@ CheckPassiveGrabsOnWindow(
         }
 
         free(xE);
-        return grab;
+        break;
     }
-    return NULL;
+
+    return grab;
 #undef CORE_MATCH
 #undef XI_MATCH
 #undef XI2_MATCH
@@ -4632,7 +4633,7 @@ DeviceEnterLeaveEvent(
         TryClientEvents(rClient(grab), mouse, (xEvent*)event, 1, mask,
                         filter, grab);
     } else {
-        if (!GetWindowXI2Mask(mouse, pWin, (xEvent*)event))
+        if (!WindowXI2MaskIsset(mouse, pWin, (xEvent*)event))
             goto out;
         DeliverEventsToWindow(mouse, pWin, (xEvent*)event, 1, filter,
                               NullGrab);
diff --git a/include/input.h b/include/input.h
index 87bb2aa01..8e7b47a4c 100644
--- a/include/input.h
+++ b/include/input.h
@@ -535,7 +535,7 @@ extern _X_EXPORT void FreeInputAttributes(InputAttributes *attrs);
 /* misc event helpers */
 extern Mask GetEventMask(DeviceIntPtr dev, xEvent* ev, InputClientsPtr clients);
 extern Mask GetEventFilter(DeviceIntPtr dev, xEvent *event);
-extern Mask GetWindowXI2Mask(DeviceIntPtr dev, WindowPtr win, xEvent* ev);
+extern Bool WindowXI2MaskIsset(DeviceIntPtr dev, WindowPtr win, xEvent* ev);
 void FixUpEventFromWindow(SpritePtr pSprite,
                           xEvent *xE,
                           WindowPtr pWin,
diff --git a/include/inputstr.h b/include/inputstr.h
index 0a2128732..f482a2294 100644
--- a/include/inputstr.h
+++ b/include/inputstr.h
@@ -72,7 +72,7 @@ extern _X_EXPORT int CountBits(const uint8_t *mask, int len);
  * this number here is bumped.
  */
 #define XI2LASTEVENT    17 /* XI_RawMotion */
-#define XI2MASKSIZE     ((XI2LASTEVENT + 7)/8) /* no of bits for masks */
+#define XI2MASKSIZE     ((XI2LASTEVENT >> 3) + 1) /* no of bytes for masks */
 
 /**
  * Scroll types for ::SetScrollValuator and the scroll type in the
diff --git a/include/misc.h b/include/misc.h
index 2e8dd1b89..ef86fa539 100644
--- a/include/misc.h
+++ b/include/misc.h
@@ -359,4 +359,11 @@ typedef struct _CharInfo *CharInfoPtr; /* also in fonts/include/font.h */
 extern _X_EXPORT unsigned long globalSerialNumber;
 extern _X_EXPORT unsigned long serverGeneration;
 
+#define BUG_WARN(cond)                                                    \
+          do { if (cond) {                                                \
+              ErrorF("BUG: triggered 'if (" #cond ")'\nBUG: %s:%d in %s()\n",     \
+                      __FILE__, __LINE__, __func__);                      \
+              xorg_backtrace();                                           \
+          } } while(0)
+
 #endif /* MISC_H */
diff --git a/test/misc.c b/test/misc.c
index d98449ba0..1f6cb9a94 100644
--- a/test/misc.c
+++ b/test/misc.c
@@ -76,7 +76,6 @@ static void dix_update_desktop_dimensions(void)
 
 #define assert_dimensions(_x, _y, _w, _h) \
     update_desktop_dimensions();          \
-    printf("%d %d %d %d\n", screenInfo.x, screenInfo.y, screenInfo.width, screenInfo.height); \
     assert(screenInfo.x == _x);           \
     assert(screenInfo.y == _y);           \
     assert(screenInfo.width == _w);       \
@@ -88,8 +87,6 @@ static void dix_update_desktop_dimensions(void)
     screenInfo.screens[idx]->width = _w;  \
     screenInfo.screens[idx]->height = _h; \
 
-    printf("Testing\n");
-
     /* single screen */
     screenInfo.numScreens = 1;
     set_screen(0, x, y, w, h);