Merge "Remove redundant memory barrier" (04112075) · Commits · e / os / android_frameworks_base

include/utils/threads.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -526,6 +526,7 @@ private:
		Thread& operator=(const Thread&);
		static int _threadLoop(void* user);
		const bool mCanCallJava;
		// always hold mLock when reading or writing
		thread_id_t mThread;
		mutable Mutex mLock;
		Condition mThreadExitedCondition;

+5 −8

Original line number	Diff line number	Diff line
		@@ -168,6 +168,9 @@ int androidCreateRawThreadEtc(android_thread_func_t entryFunction,
		return 0;
		}

		// Note that *threadID is directly available to the parent only, as it is
		// assigned after the child starts. Use memory barrier / lock if the child
		// or other threads also need access.
		if (threadId != NULL) {
		*threadId = (android_thread_id_t)thread; // XXX: this is not portable
		}
		@@ -718,7 +721,6 @@ status_t Thread::run(const char* name, int32_t priority, size_t stack)
		res = androidCreateRawThreadEtc(_threadLoop,
		this, name, priority, stack, &mThread);
		}
		// The new thread wakes up at _threadLoop, but immediately blocks on mLock

		if (res == false) {
		mStatus = UNKNOWN_ERROR; // something happened!
		@@ -742,11 +744,6 @@ int Thread::_threadLoop(void* user)
		{
		Thread* const self = static_cast<Thread*>(user);

		// force a memory barrier before reading any fields, in particular mHoldSelf
		{
		Mutex::Autolock _l(self->mLock);
		}

		sp<Thread> strong(self->mHoldSelf);
		wp<Thread> weak(strong);
		self->mHoldSelf.clear();
		@@ -816,6 +813,7 @@ void Thread::requestExit()

		status_t Thread::requestExitAndWait()
		{
		Mutex::Autolock _l(mLock);
		if (mThread == getThreadId()) {
		LOGW(
		"Thread (this=%p): don't call waitForExit() from this "
		@@ -825,9 +823,8 @@ status_t Thread::requestExitAndWait()
		return WOULD_BLOCK;
		}

		requestExit();
		mExitPending = true;

		Mutex::Autolock _l(mLock);
		while (mRunning == true) {
		mThreadExitedCondition.wait(mLock);
		}