Changeset 39487 in webkit for trunk/JavaScriptCore/wtf/ThreadingQt.cpp

Timestamp:

Dec 27, 2008, 6:54:12 PM (16 years ago)

Author:

[email protected]

Message:

<rdar://problem/6467376> Race condition in WTF::currentThread can lead to a thread using two different identifiers during its lifetime

If a newly-created thread calls WTF::currentThread() before WTF::createThread calls establishIdentifierForPthreadHandle
then more than one identifier will be used for the same thread. We can avoid this by adding some extra synchronization
during thread creation that delays the execution of the thread function until the thread identifier has been set up, and
an assertion to catch this problem should it reappear in the future.

Reviewed by Alexey Proskuryakov.

• wtf/Threading.cpp: Added.

(WTF::NewThreadContext::NewThreadContext):
(WTF::threadEntryPoint):
(WTF::createThread): Add cross-platform createThread function that delays the execution of the thread function until
after the thread identifier has been set up.

• wtf/Threading.h:
• wtf/ThreadingGtk.cpp:

(WTF::establishIdentifierForThread):
(WTF::createThreadInternal):

• wtf/ThreadingNone.cpp:

(WTF::createThreadInternal):

• wtf/ThreadingPthreads.cpp:

(WTF::establishIdentifierForPthreadHandle):
(WTF::createThreadInternal):

• wtf/ThreadingQt.cpp:

(WTF::identifierByQthreadHandle):
(WTF::establishIdentifierForThread):
(WTF::createThreadInternal):

• wtf/ThreadingWin.cpp:

(WTF::storeThreadHandleByIdentifier):
(WTF::createThreadInternal):

Add Threading.cpp to the build.

• GNUmakefile.am:
• JavaScriptCore.pri:
• JavaScriptCore.scons:
• JavaScriptCore.vcproj/WTF/WTF.vcproj:
• JavaScriptCore.xcodeproj/project.pbxproj:
• JavaScriptCoreSources.bkl:

File:

• trunk/JavaScriptCore/wtf/ThreadingQt.cpp (modified) (3 diffs)

trunk/JavaScriptCore/wtf/ThreadingQt.cpp

@@ -81 +81 @@
 }
 
-static ThreadIdentifier establishIdentifierForThread(QThread*& thread)
-{
-    MutexLocker locker(threadMapMutex());
-
-    static ThreadIdentifier identifierCount = 1;
-
-    threadMap().add(identifierCount, thread);
-
-    return identifierCount++;
-}
-
-static void clearThreadForIdentifier(ThreadIdentifier id)
-{
-    MutexLocker locker(threadMapMutex());
-
-    ASSERT(threadMap().contains(id));
-
-    threadMap().remove(id);
-}
-
 static ThreadIdentifier identifierByQthreadHandle(QThread*& thread)
 {
@@ -112 +92 @@
 
     return 0;
+}
+
+static ThreadIdentifier establishIdentifierForThread(QThread*& thread)
+{
+    ASSERT(!identifierByQthreadHandle(thread));
+
+    MutexLocker locker(threadMapMutex());
+
+    static ThreadIdentifier identifierCount = 1;
+
+    threadMap().add(identifierCount, thread);
+
+    return identifierCount++;
+}
+
+static void clearThreadForIdentifier(ThreadIdentifier id)
+{
+    MutexLocker locker(threadMapMutex());
+
+    ASSERT(threadMap().contains(id));
+
+    threadMap().remove(id);
 }
 
@@ -146 +148 @@
 }
 
-ThreadIdentifier createThread(ThreadFunction entryPoint, void* data, const char*)
+ThreadIdentifier createThreadInternal(ThreadFunction entryPoint, void* data, const char*)
 {
     ThreadPrivate* thread = new ThreadPrivate(entryPoint, data);