Bug 463289 - nsNativeModuleLoader doesn't protect its internal data structures, and is accessed on multiple threads (symptom is RECURSION_LEVEL assertions in pldhash.c). This patch is the simple-but-slow path: proxy all non-main-thread requests to the main thread. This is probably sufficient because asking for modules is a relatively rare activity: the component manager caches the factory objects after a lookup, r=brendan

--HG--
extra : rebase_source : 3118096536b6271886d5c35a3486bb278dc0fd86

xpcom/components/nsNativeComponentLoader.cpp

@@ -60,10 +60,12 @@
 #include "nsComponentManager.h"
 #include "nsCRTGlue.h"
 #include "nsModule.h"
+#include "nsThreadUtils.h"
 #include "nsTraceRefcntImpl.h"
 
 #include "nsILocalFile.h"
 #include "nsIModule.h"
+#include "nsIProxyObjectManager.h"
 
 #ifdef XP_WIN
 #include <windows.h>
@@ -98,6 +100,8 @@ NS_IMPL_RELEASE_USING_AGGREGATOR(nsNativeModuleLoader,
 nsresult
 nsNativeModuleLoader::Init()
 {
+    NS_ASSERTION(NS_IsMainThread(), "Startup not on main thread?");
+
     LOG(PR_LOG_DEBUG, ("nsNativeModuleLoader::Init()"));
 
     return mLibraries.Init() ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
@@ -108,6 +112,23 @@ nsNativeModuleLoader::LoadModule(nsILocalFile* aFile, nsIModule* *aResult)
 {
     nsresult rv;
 
+    if (!NS_IsMainThread()) {
+        // If this call is off the main thread, synchronously proxy it
+        // to the main thread.
+        
+        nsCOMPtr<nsIModuleLoader> proxythis;
+        rv = NS_GetProxyForObject(NS_PROXY_TO_MAIN_THREAD,
+                                  NS_GET_IID(nsIModuleLoader),
+                                  this, NS_PROXY_SYNC,
+                                  getter_AddRefs(proxythis));
+        if (NS_FAILED(rv))
+            return rv;
+
+        return proxythis->LoadModule(aFile, aResult);
+    }
+
+    NS_ASSERTION(NS_IsMainThread(), "LoadModule should always proxy to the main thread!");
+
     // Only load components that end in the proper dynamic library suffix
     nsCAutoString filePath;
     aFile->GetNativePath(filePath);
@@ -255,6 +276,8 @@ nsNativeModuleLoader::UnloaderFunc(nsIHashable* aHashedFile,
 void
 nsNativeModuleLoader::UnloadLibraries()
 {
+    NS_ASSERTION(NS_IsMainThread(), "Shutdown not on main thread?");
+
     mLibraries.Enumerate(ReleaserFunc, nsnull);
     mLibraries.Enumerate(UnloaderFunc, nsnull);
 }