Bug 1663747: Part 1 - Fix sCurrentShutdownPhase and add PastShutdownPhase() API. r=nika

Differential Revision: https://phabricator.services.mozilla.com/D89809

dom/ipc/ContentParent.cpp

@@ -2565,6 +2565,14 @@ ContentParent::~ContentParent() {
 }
 
 bool ContentParent::InitInternal(ProcessPriority aInitialPriority) {
+  // We can't access the locale service after shutdown has started. Since we
+  // can't init the process without it, and since we're going to be canceling
+  // whatever load attempt that initiated this process creation anyway, just
+  // bail out now if shutdown has already started.
+  if (PastShutdownPhase(ShutdownPhase::Shutdown)) {
+    return false;
+  }
+
   XPCOMInitData xpcomInit;
 
   MOZ_LOG(ContentParent::GetLog(), LogLevel::Debug,

gfx/vr/VRServiceHost.cpp

@@ -237,7 +237,10 @@ void VRServiceHost::SendPuppetSubmitToVRProcess(
 }
 
 void VRServiceHost::PuppetReset() {
-  if (!mVRProcessEnabled) {
+  // If we're already into ShutdownFinal, the VRPuppetCommandBuffer instance
+  // will have been cleared, so don't try to access it after that point.
+  if (!mVRProcessEnabled &&
+      !(NS_IsMainThread() && PastShutdownPhase(ShutdownPhase::ShutdownFinal))) {
     // Puppet is running in this process, tell it to reset directly.
     VRPuppetCommandBuffer::Get().Reset();
   }

intl/strres/nsStringBundle.cpp

@@ -26,6 +26,7 @@
 #include "nsSimpleEnumerator.h"
 #include "nsStringStream.h"
 #include "mozilla/BinarySearch.h"
+#include "mozilla/ClearOnShutdown.h"
 #include "mozilla/ResultExtensions.h"
 #include "mozilla/URLPreloader.h"
 #include "mozilla/ResultExtensions.h"
@@ -483,6 +484,19 @@ nsresult SharedStringBundle::LoadProperties() {
     return NS_OK;
   }
 
+  MOZ_ASSERT(NS_IsMainThread(),
+             "String bundles must be initialized on the main thread "
+             "before they may be used off-main-thread");
+
+  // We can't access the locale service after shutdown has started, which
+  // means we can't attempt to load chrome: locale resources (which most of
+  // our string bundles come from). Since shared string bundles won't be
+  // useful after shutdown has started anyway (and we almost certainly got
+  // here from a pre-load attempt in an idle task), just bail out.
+  if (PastShutdownPhase(ShutdownPhase::Shutdown)) {
+    return NS_ERROR_ILLEGAL_DURING_SHUTDOWN;
+  }
+
   // We should only populate shared memory string bundles in the parent
   // process. Instances in the child process should always be instantiated
   // with a shared memory file descriptor sent from the parent.

xpcom/base/ClearOnShutdown.cpp

@@ -16,8 +16,7 @@ ShutdownPhase sCurrentShutdownPhase = ShutdownPhase::NotInShutdown;
 
 void InsertIntoShutdownList(ShutdownObserver* aObserver, ShutdownPhase aPhase) {
   // Adding a ClearOnShutdown for a "past" phase is an error.
-  if (!(static_cast<size_t>(sCurrentShutdownPhase) <
-        static_cast<size_t>(aPhase))) {
+  if (PastShutdownPhase(aPhase)) {
     MOZ_ASSERT(false, "ClearOnShutdown for phase that already was cleared");
     aObserver->Shutdown();
     delete aObserver;
@@ -39,8 +38,11 @@ void KillClearOnShutdown(ShutdownPhase aPhase) {
 
   MOZ_ASSERT(NS_IsMainThread());
   // Shutdown only goes one direction...
-  MOZ_ASSERT(static_cast<size_t>(sCurrentShutdownPhase) <
-             static_cast<size_t>(aPhase));
+  MOZ_ASSERT(!PastShutdownPhase(aPhase));
+
+  // Set the phase before notifying observers to make sure that they can't run
+  // any code which isn't allowed to run after the start of this phase.
+  sCurrentShutdownPhase = aPhase;
 
   // It's impossible to add an entry for a "past" phase; this is blocked in
   // ClearOnShutdown, but clear them out anyways in case there are phases

xpcom/base/ClearOnShutdown.h

@@ -129,6 +129,13 @@ inline void RunOnShutdown(CallableT&& aCallable,
       new FunctionInvoker(std::forward<CallableT>(aCallable)), aPhase);
 }
 
+inline bool PastShutdownPhase(ShutdownPhase aPhase) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  return size_t(ClearOnShutdown_Internal::sCurrentShutdownPhase) >=
+         size_t(aPhase);
+}
+
 // Called when XPCOM is shutting down, after all shutdown notifications have
 // been sent and after all threads' event loops have been purged.
 void KillClearOnShutdown(ShutdownPhase aPhase);

xpcom/threads/ThrottledEventQueue.cpp

@@ -261,8 +261,10 @@ class ThrottledEventQueue::Inner final : public nsISupports {
   static already_AddRefed<Inner> Create(nsISerialEventTarget* aBaseTarget,
                                         const char* aName, uint32_t aPriority) {
     MOZ_ASSERT(NS_IsMainThread());
-    MOZ_ASSERT(ClearOnShutdown_Internal::sCurrentShutdownPhase ==
-               ShutdownPhase::NotInShutdown);
+    // FIXME: This assertion only worked when `sCurrentShutdownPhase` was not
+    // being updated.
+    // MOZ_ASSERT(ClearOnShutdown_Internal::sCurrentShutdownPhase ==
+    //            ShutdownPhase::NotInShutdown);
 
     RefPtr<Inner> ref = new Inner(aBaseTarget, aName, aPriority);
     return ref.forget();