From b34e6f5815ab838667a77bfcd1d59794c54c58ac Mon Sep 17 00:00:00 2001
From: Benjamin Bouvier <benj@benj.me>
Date: Tue, 22 Sep 2015 19:26:21 +0200
Subject: [PATCH] Bug 1207232: Let lockOwner be Atomic; r=terrence

--HG--
extra : commitid : FFrGdIRgTdY
extra : rebase_source : c04b2c8ed994fd3d74f3a4467015199d03e130ee
---
 js/src/gc/GCRuntime.h       | 14 ++++++++------
 js/src/jsgc.cpp             |  5 ++---
 js/src/vm/HelperThreads.cpp | 13 +++++--------
 js/src/vm/HelperThreads.h   |  4 +---
 4 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/js/src/gc/GCRuntime.h b/js/src/gc/GCRuntime.h
index c7376b22a4f0..e9521ce09e3c 100644
--- a/js/src/gc/GCRuntime.h
+++ b/js/src/gc/GCRuntime.h
@@ -673,7 +673,7 @@ class GCRuntime
     bool onBackgroundThread() { return helperState.onBackgroundThread(); }
 
     bool currentThreadOwnsGCLock() {
-        return lockOwner == PR_GetCurrentThread();
+        return lockOwner.value == PR_GetCurrentThread();
     }
 
 #endif // DEBUG
@@ -684,15 +684,17 @@ class GCRuntime
 
     void lockGC() {
         PR_Lock(lock);
-        MOZ_ASSERT(!lockOwner);
 #ifdef DEBUG
-        lockOwner = PR_GetCurrentThread();
+        MOZ_ASSERT(!lockOwner.value);
+        lockOwner.value = PR_GetCurrentThread();
 #endif
     }
 
     void unlockGC() {
-        MOZ_ASSERT(lockOwner == PR_GetCurrentThread());
-        lockOwner = nullptr;
+#ifdef DEBUG
+        MOZ_ASSERT(lockOwner.value == PR_GetCurrentThread());
+        lockOwner.value = nullptr;
+#endif
         PR_Unlock(lock);
     }
 
@@ -1298,7 +1300,7 @@ class GCRuntime
 
     /* Synchronize GC heap access between main thread and GCHelperState. */
     PRLock* lock;
-    mozilla::DebugOnly<PRThread*> lockOwner;
+    mozilla::DebugOnly<mozilla::Atomic<PRThread*>> lockOwner;
 
     BackgroundAllocTask allocTask;
     GCHelperState helperState;
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index e12a7d8b913c..f945eb60bf61 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -1176,7 +1176,6 @@ GCRuntime::GCRuntime(JSRuntime* rt) :
     noGCOrAllocationCheck(0),
 #endif
     lock(nullptr),
-    lockOwner(nullptr),
     allocTask(rt, emptyChunks_),
     helperState(rt)
 {
@@ -3409,11 +3408,11 @@ GCHelperState::waitForBackgroundThread()
     MOZ_ASSERT(CurrentThreadCanAccessRuntime(rt));
 
 #ifdef DEBUG
-    rt->gc.lockOwner = nullptr;
+    rt->gc.lockOwner.value = nullptr;
 #endif
     PR_WaitCondVar(done, PR_INTERVAL_NO_TIMEOUT);
 #ifdef DEBUG
-    rt->gc.lockOwner = PR_GetCurrentThread();
+    rt->gc.lockOwner.value = PR_GetCurrentThread();
 #endif
 }
 
diff --git a/js/src/vm/HelperThreads.cpp b/js/src/vm/HelperThreads.cpp
index 37a0988d2735..6c6cc9fe73ad 100644
--- a/js/src/vm/HelperThreads.cpp
+++ b/js/src/vm/HelperThreads.cpp
@@ -492,9 +492,6 @@ GlobalHelperThreadState::GlobalHelperThreadState()
    threads(nullptr),
    asmJSCompilationInProgress(false),
    helperLock(nullptr),
-#ifdef DEBUG
-   lockOwner(nullptr),
-#endif
    consumerWakeup(nullptr),
    producerWakeup(nullptr),
    pauseWakeup(nullptr),
@@ -545,7 +542,7 @@ GlobalHelperThreadState::lock()
     AssertCurrentThreadCanLock(HelperThreadStateLock);
     PR_Lock(helperLock);
 #ifdef DEBUG
-    lockOwner = PR_GetCurrentThread();
+    lockOwner.value = PR_GetCurrentThread();
 #endif
 }
 
@@ -554,7 +551,7 @@ GlobalHelperThreadState::unlock()
 {
     MOZ_ASSERT(isLocked());
 #ifdef DEBUG
-    lockOwner = nullptr;
+    lockOwner.value = nullptr;
 #endif
     PR_Unlock(helperLock);
 }
@@ -563,7 +560,7 @@ GlobalHelperThreadState::unlock()
 bool
 GlobalHelperThreadState::isLocked()
 {
-    return lockOwner == PR_GetCurrentThread();
+    return lockOwner.value == PR_GetCurrentThread();
 }
 #endif
 
@@ -572,14 +569,14 @@ GlobalHelperThreadState::wait(CondVar which, uint32_t millis)
 {
     MOZ_ASSERT(isLocked());
 #ifdef DEBUG
-    lockOwner = nullptr;
+    lockOwner.value = nullptr;
 #endif
     DebugOnly<PRStatus> status =
         PR_WaitCondVar(whichWakeup(which),
                        millis ? PR_MillisecondsToInterval(millis) : PR_INTERVAL_NO_TIMEOUT);
     MOZ_ASSERT(status == PR_SUCCESS);
 #ifdef DEBUG
-    lockOwner = PR_GetCurrentThread();
+    lockOwner.value = PR_GetCurrentThread();
 #endif
 }
 
diff --git a/js/src/vm/HelperThreads.h b/js/src/vm/HelperThreads.h
index 30fcfc49371d..0c22485f43a5 100644
--- a/js/src/vm/HelperThreads.h
+++ b/js/src/vm/HelperThreads.h
@@ -242,9 +242,7 @@ class GlobalHelperThreadState
      * used by all condition variables.
      */
     PRLock* helperLock;
-#ifdef DEBUG
-    PRThread* lockOwner;
-#endif
+    mozilla::DebugOnly<mozilla::Atomic<PRThread*>> lockOwner;
 
     /* Condvars for threads waiting/notifying each other. */
     PRCondVar* consumerWakeup;