Bug 323195 - XPCAutoUnlock messes with detection of potential deadlocks, patch by Matthew Gertner, r=brendan

js/src/xpconnect/src/xpcprivate.h

@@ -336,20 +336,10 @@ private:
 
 /************************************************/
 
-class XPCAutoUnlock : public nsAutoLockBase {
+class XPCAutoUnlock : public nsAutoUnlockBase {
 public:
-
-    static XPCLock* NewLock(const char* name)
-                        {return nsAutoMonitor::NewMonitor(name);}
-    static void     DestroyLock(XPCLock* lock)
-                        {nsAutoMonitor::DestroyMonitor(lock);}
-
     XPCAutoUnlock(XPCLock* lock)
-#ifdef DEBUG
-        : nsAutoLockBase(lock ? (void*) lock : (void*) this, eAutoMonitor),
-#else
-        : nsAutoLockBase(lock, eAutoMonitor),
-#endif
+        : nsAutoUnlockBase(lock),
           mLock(lock)
     {
         if(mLock)

xpcom/threads/nsAutoLock.cpp

@@ -349,6 +349,29 @@ void nsAutoLockBase::Hide()
         prev->mDown = mDown;
 }
 
+nsAutoUnlockBase::nsAutoUnlockBase(void* addr)
+{
+    if (addr)
+    {
+        nsAutoLockBase* curr = (nsAutoLockBase*) PR_GetThreadPrivate(LockStackTPI);
+        while (curr && curr->mAddr != addr)
+            curr = curr->mDown;
+
+        mLock = curr;
+    }
+    else
+        mLock = nsnull;
+
+    if (mLock)
+        mLock->Hide();
+}
+
+nsAutoUnlockBase::~nsAutoUnlockBase()
+{
+    if (mLock)
+        mLock->Show();
+}
+
 #endif /* DEBUG */
 
 PRMonitor* nsAutoMonitor::NewMonitor(const char* name)

xpcom/threads/nsAutoLock.h

@@ -116,6 +116,8 @@
  * Clients of derived classes need not play with this superclass.
  **/
 class NS_COM nsAutoLockBase {
+    friend class nsAutoUnlockBase;
+
 protected:
     nsAutoLockBase() {}
     enum nsAutoLockType {eAutoLock, eAutoMonitor, eAutoCMonitor};
@@ -139,6 +141,26 @@ protected:
 #endif
 };
 
+/**
+ * nsAutoUnlockBase
+ * This is the base class for stack-based unlocking objects.
+ * It unlocks locking objects based on nsAutoLockBase.
+ **/
+class NS_COM nsAutoUnlockBase {
+protected:
+    nsAutoUnlockBase() {}
+
+#ifdef DEBUG
+    nsAutoUnlockBase(void* addr);
+    ~nsAutoUnlockBase();
+
+    nsAutoLockBase* mLock;
+#else
+    nsAutoUnlockBase(void* addr) {}
+    ~nsAutoUnlockBase() {}
+#endif
+};
+
 /** 
  * nsAutoLock
  * Stack-based locking object for PRLock.