Commit e52a3b60 authored Feb 18, 2020 by Steven Moreland

Disallow shrinking threadpool size once started.

If a larger threadpool is started, and concurrent binder transactions
are cause these threads to actually be started, and then we shrink
the threadpool, these extra threads won't be shut down. So, when we
detect that this race may happen, we abort with an error.

It's best practice to setup a threadpool at process startup time.

Bug: 147699567
Test: TH
Change-Id: I12d2e6e6b1ebf92c2b2abbfccffb011c4248d8ec

parent f2a15e87

libs/binder/ProcessState.cpp

+2 −0

Original line number	Diff line number	Diff line
		@@ -324,6 +324,8 @@ void ProcessState::spawnPooledThread(bool isMain)
		}

		status_t ProcessState::setThreadPoolMaxThreadCount(size_t maxThreads) {
		LOG_ALWAYS_FATAL_IF(mThreadPoolStarted && maxThreads < mMaxThreads,
		"Binder threadpool cannot be shrunk after starting");
		status_t result = NO_ERROR;
		if (ioctl(mDriverFD, BINDER_SET_MAX_THREADS, &maxThreads) != -1) {
		mMaxThreads = maxThreads;