Modified: trunk/Source/WebCore/ChangeLog (221082 => 221083)
--- trunk/Source/WebCore/ChangeLog 2017-08-23 17:16:51 UTC (rev 221082)
+++ trunk/Source/WebCore/ChangeLog 2017-08-23 17:41:39 UTC (rev 221083)
@@ -1,3 +1,22 @@
+2017-08-23 Yusuke Suzuki <[email protected]>
+
+ Race condition in StartWebThread causing crash
+ https://bugs.webkit.org/show_bug.cgi?id=175852
+
+ Reviewed by Mark Lam.
+
+ When starting web thread, the main thread waits for completion of web thread initialization
+ by using pthread_cond_t. However, the main thread may be woken up due to the existence of
+ the spurious wake up of pthread_cond_t.
+
+ Instead, we should use WTF::Lock and WTF::Condition. Since our StartWebThread already calls
+ WTF::initializeThreading, it is safe to use WTF::Lock and WTF::Condition. And our WTF::Condition
+ does not have the spurious wake up problem as described in Condition.h.
+
+ * platform/ios/wak/WebCoreThread.mm:
+ (RunWebThread):
+ (StartWebThread):
+
2017-08-23 Brent Fulgham <[email protected]>
Ensure media controls host exists before using it
Modified: trunk/Source/WebCore/platform/ios/wak/WebCoreThread.mm (221082 => 221083)
--- trunk/Source/WebCore/platform/ios/wak/WebCoreThread.mm 2017-08-23 17:16:51 UTC (rev 221082)
+++ trunk/Source/WebCore/platform/ios/wak/WebCoreThread.mm 2017-08-23 17:41:39 UTC (rev 221083)
@@ -127,8 +127,8 @@
static CFRunLoopObserverRef mainRunLoopAutoUnlockObserver;
-static pthread_mutex_t startupLock = PTHREAD_MUTEX_INITIALIZER;
-static pthread_cond_t startupCondition = PTHREAD_COND_INITIALIZER;
+static StaticLock startupLock;
+static StaticCondition startupCondition;
static WebThreadContext *webThreadContext;
static pthread_key_t threadContextKey;
@@ -681,15 +681,11 @@
WebThreadReleaseSource = CFRunLoopSourceCreate(NULL, -1, &ReleaseSourceContext);
CFRunLoopAddSource(webThreadRunLoop, WebThreadReleaseSource, kCFRunLoopDefaultMode);
- int result = pthread_mutex_lock(&startupLock);
- ASSERT_WITH_MESSAGE(result == 0, "startup lock failed with code:%d", result);
+ {
+ LockHolder locker(startupLock);
+ startupCondition.notifyOne();
+ }
- result = pthread_cond_signal(&startupCondition);
- ASSERT_WITH_MESSAGE(result == 0, "startup signal failed with code:%d", result);
-
- result = pthread_mutex_unlock(&startupLock);
- ASSERT_WITH_MESSAGE(result == 0, "startup unlock failed with code:%d", result);
-
while (1)
CFRunLoopRunInMode(kCFRunLoopDefaultMode, DistantFuture, true);
@@ -758,21 +754,18 @@
pthread_attr_setschedparam(&tattr, ¶m);
// Wait for the web thread to startup completely before we continue.
- int result = pthread_mutex_lock(&startupLock);
- ASSERT_WITH_MESSAGE(result == 0, "startup lock failed with code:%d", result);
+ {
+ LockHolder locker(startupLock);
- // Propagate the mainThread's fenv to workers & the web thread.
- FloatingPointEnvironment::singleton().saveMainThreadEnvironment();
+ // Propagate the mainThread's fenv to workers & the web thread.
+ FloatingPointEnvironment::singleton().saveMainThreadEnvironment();
- pthread_create(&webThread, &tattr, RunWebThread, NULL);
- pthread_attr_destroy(&tattr);
+ pthread_create(&webThread, &tattr, RunWebThread, NULL);
+ pthread_attr_destroy(&tattr);
- result = pthread_cond_wait(&startupCondition, &startupLock);
- ASSERT_WITH_MESSAGE(result == 0, "startup wait failed with code:%d", result);
+ startupCondition.wait(startupLock);
+ }
- result = pthread_mutex_unlock(&startupLock);
- ASSERT_WITH_MESSAGE(result == 0, "startup unlock failed with code:%d", result);
-
initializeApplicationUIThreadIdentifier();
}
