--- xnu/xnu-792.25.20/iokit/Kernel/IODataQueue.cpp
+++ xnu/xnu-201/iokit/Kernel/IODataQueue.cpp
@@ -71,7 +71,7 @@
         return false;
     }
 
-    dataQueue = (IODataQueueMemory *)IOMallocAligned(round_page_32(size + DATA_QUEUE_MEMORY_HEADER_SIZE), PAGE_SIZE);
+    dataQueue = (IODataQueueMemory *)IOMallocAligned(round_page(size + DATA_QUEUE_MEMORY_HEADER_SIZE), PAGE_SIZE);
     if (dataQueue == 0) {
         return false;
     }
@@ -91,7 +91,7 @@
 void IODataQueue::free()
 {
     if (dataQueue) {
-        IOFreeAligned(dataQueue, round_page_32(dataQueue->queueSize + DATA_QUEUE_MEMORY_HEADER_SIZE));
+        IOFreeAligned(dataQueue, round_page(dataQueue->queueSize + DATA_QUEUE_MEMORY_HEADER_SIZE));
     }
 
     super::free();
@@ -105,39 +105,24 @@
     const UInt32       tail      = dataQueue->tail;
     const UInt32       entrySize = dataSize + DATA_QUEUE_ENTRY_HEADER_SIZE;
     IODataQueueEntry * entry;
-
+    
     if ( tail >= head )
     {
-        // Is there enough room at the end for the entry?
-        if ( (tail + entrySize) <= dataQueue->queueSize )
+        if ( (tail + entrySize) < dataQueue->queueSize )
         {
             entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
 
             entry->size = dataSize;
             memcpy(&entry->data, data, dataSize);
-
-            // The tail can be out of bound when the size of the new entry
-            // exactly matches the available space at the end of the queue.
-            // The tail can range from 0 to dataQueue->queueSize inclusive.
-
             dataQueue->tail += entrySize;
         }
-        else if ( head > entrySize ) 	// Is there enough room at the beginning?
+        else if ( head > entrySize )
         {
             // Wrap around to the beginning, but do not allow the tail to catch
             // up to the head.
 
             dataQueue->queue->size = dataSize;
-
-            // We need to make sure that there is enough room to set the size before
-            // doing this. The user client checks for this and will look for the size
-            // at the beginning if there isn't room for it at the end.
-
-            if ( ( dataQueue->queueSize - tail ) >= DATA_QUEUE_ENTRY_HEADER_SIZE )
-            {
-                ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
-            }
-
+            ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
             memcpy(&dataQueue->queue->data, data, dataSize);
             dataQueue->tail = entrySize;
         }