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libkern/c++/OSObject.cpp xnu-201.19.3 xnu-792.6.61
--- xnu/xnu-201.19.3/libkern/c++/OSObject.cpp
+++ xnu/xnu-792.6.61/libkern/c++/OSObject.cpp
@@ -23,10 +23,11 @@
 
 #include <libkern/c++/OSObject.h>
 #include <libkern/c++/OSSerialize.h>
-#include <libkern/c++/OSSymbol.h>
 #include <libkern/c++/OSLib.h>
 #include <libkern/c++/OSCPPDebug.h>
 #include <libkern/OSAtomic.h>
+
+#include <libkern/c++/OSCollection.h>
 
 __BEGIN_DECLS
 int debug_ivars_size;
@@ -91,8 +92,21 @@
 OSMetaClassDefineReservedUnused(OSObject, 30);
 OSMetaClassDefineReservedUnused(OSObject, 31);
 
-
-bool OSObject::init()			{ return true; }
+static const char *getClassName(const OSObject *obj)
+{
+    const OSMetaClass *meta = obj->getMetaClass();
+    return (meta) ? meta->getClassName() : "unknown class?";
+}
+
+bool OSObject::init()
+    { return true; }
+
+#if (!__ppc__) || (__GNUC__ < 3)
+
+// Implemented in assembler in post gcc 3.x systems as we have a problem
+// where the destructor in gcc2.95 gets 2 arguments.  The second argument
+// appears to be a flag argument.  I have copied the assembler from Puma xnu
+// to OSRuntimeSupport.c  So for 2.95 builds use the C 
 void OSObject::free()
 {
     const OSMetaClass *meta = getMetaClass();
@@ -101,26 +115,135 @@
 	meta->instanceDestructed();
     delete this;
 }
+#endif /* (!__ppc__) || (__GNUC__ < 3) */
 
 int OSObject::getRetainCount() const
 {
-    return retainCount;
+    return (int) ((UInt16) retainCount);
+}
+
+void OSObject::taggedRetain(const void *tag) const
+{
+    volatile UInt32 *countP = (volatile UInt32 *) &retainCount;
+    UInt32 inc = 1;
+    UInt32 origCount;
+    UInt32 newCount;
+
+    // Increment the collection bucket.
+    if ((const void *) OSTypeID(OSCollection) == tag)
+	inc |= (1UL<<16);
+
+    do {
+	origCount = *countP;
+        if ( ((UInt16) origCount | 0x1) == 0xffff ) {
+            const char *msg;
+            if (origCount & 0x1) {
+                // If count == 0xffff that means we are freeing now so we can
+                // just return obviously somebody is cleaning up dangling
+                // references.
+                msg = "Attempting to retain a freed object";
+            }
+            else {
+                // If count == 0xfffe then we have wrapped our reference count.
+                // We should stop counting now as this reference must be
+                // leaked rather than accidently wrapping around the clock and
+                // freeing a very active object later.
+
+#if !DEBUG
+		break;	// Break out of update loop which pegs the reference
+#else DEBUG
+                // @@@ gvdl: eventually need to make this panic optional
+                // based on a boot argument i.e. debug= boot flag
+                msg = "About to wrap the reference count, reference leak?";
+#endif /* !DEBUG */
+            }
+            panic("OSObject::refcount: %s", msg);
+        }
+
+	newCount = origCount + inc;
+    } while (!OSCompareAndSwap(origCount, newCount, (UInt32 *) countP));
+}
+
+void OSObject::taggedRelease(const void *tag) const
+{
+    taggedRelease(tag, 1);
+}
+
+void OSObject::taggedRelease(const void *tag, const int when) const
+{
+    volatile UInt32 *countP = (volatile UInt32 *) &retainCount;
+    UInt32 dec = 1;
+    UInt32 origCount;
+    UInt32 newCount;
+    UInt32 actualCount;
+
+    // Increment the collection bucket.
+    if ((const void *) OSTypeID(OSCollection) == tag)
+	dec |= (1UL<<16);
+
+    do {
+	origCount = *countP;
+        
+        if ( ((UInt16) origCount | 0x1) == 0xffff ) {
+            if (origCount & 0x1) {
+                // If count == 0xffff that means we are freeing now so we can
+                // just return obviously somebody is cleaning up some dangling
+                // references.  So we blow out immediately.
+                return;
+            }
+            else {
+                // If count == 0xfffe then we have wrapped our reference
+                // count.  We should stop counting now as this reference must be
+                // leaked rather than accidently freeing an active object later.
+
+#if !DEBUG
+		return;	// return out of function which pegs the reference
+#else DEBUG
+                // @@@ gvdl: eventually need to make this panic optional
+                // based on a boot argument i.e. debug= boot flag
+                panic("OSObject::refcount: %s",
+                      "About to unreference a pegged object, reference leak?");
+#endif /* !DEBUG */
+            }
+        }
+	actualCount = origCount - dec;
+        if ((UInt16) actualCount < when)
+            newCount = 0xffff;
+        else
+            newCount = actualCount;
+
+    } while (!OSCompareAndSwap(origCount, newCount, (UInt32 *) countP));
+
+    //
+    // This panic means that we have just attempted to release an object
+    // who's retain count has gone to less than the number of collections
+    // it is a member off.  Take a panic immediately.
+    // In Fact the panic MAY not be a registry corruption but it is 
+    // ALWAYS the wrong thing to do.  I call it a registry corruption 'cause
+    // the registry is the biggest single use of a network of collections.
+    //
+    if ((UInt16) actualCount < (actualCount >> 16))
+	panic("A driver releasing a(n) %s has corrupted the registry\n",
+	    getClassName(this));
+
+    // Check for a 'free' condition and that if we are first through
+    if (newCount == 0xffff)
+	((OSObject *) this)->free();
+}
+
+void OSObject::release() const
+{
+    taggedRelease(0);
 }
 
 void OSObject::retain() const
 {
-    OSIncrementAtomic((SInt32 *) &retainCount);
+    taggedRetain(0);
 }
 
 void OSObject::release(int when) const
 {
-    if (OSDecrementAtomic((SInt32 *) &retainCount) <= when)
-	((OSObject *) this)->free();
-}
-
-void OSObject::release() const
-{
-    release(1);
+    taggedRelease(0, when);
 }
 
 bool OSObject::serialize(OSSerialize *s) const
@@ -129,10 +252,7 @@
 
     if (!s->addXMLStartTag(this, "string")) return false;
 
-    const OSMetaClass *meta = getMetaClass();
-    const char *className = (meta)? meta->getClassName() : "unknown class?";
-
-    if (!s->addString(className)) return false;
+    if (!s->addString(getClassName(this))) return false;
     if (!s->addString(" is not serializable")) return false;
     
     return s->addXMLEndTag("string");