binder: remove mutex from transaction processing loop
atomic ops are enough for the various count fields, we don't need a
completely consistent view of them.
Bug: 333946800
Test: atest --test-mapping frameworks/native/libs/binder/TEST_MAPPING
Change-Id: I01f55a36f7421e4955e2b0d3a6500b183573d765
diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index fb2781b..4f7cbad 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -407,9 +407,7 @@
ALOGV("Spawning new pooled thread, name=%s\n", name.c_str());
sp<Thread> t = sp<PoolThread>::make(isMain);
t->run(name.c_str());
- pthread_mutex_lock(&mThreadCountLock);
mKernelStartedThreads++;
- pthread_mutex_unlock(&mThreadCountLock);
}
// TODO: if startThreadPool is called on another thread after the process
// starts up, the kernel might think that it already requested those
@@ -432,19 +430,19 @@
}
size_t ProcessState::getThreadPoolMaxTotalThreadCount() const {
- pthread_mutex_lock(&mThreadCountLock);
- auto detachGuard = make_scope_guard([&]() { pthread_mutex_unlock(&mThreadCountLock); });
-
if (mThreadPoolStarted) {
- LOG_ALWAYS_FATAL_IF(mKernelStartedThreads > mMaxThreads + 1,
- "too many kernel-started threads: %zu > %zu + 1", mKernelStartedThreads,
- mMaxThreads);
+ size_t kernelStarted = mKernelStartedThreads;
+ size_t max = mMaxThreads;
+ size_t current = mCurrentThreads;
+
+ LOG_ALWAYS_FATAL_IF(kernelStarted > max + 1,
+ "too many kernel-started threads: %zu > %zu + 1", kernelStarted, max);
// calling startThreadPool starts a thread
size_t threads = 1;
// the kernel is configured to start up to mMaxThreads more threads
- threads += mMaxThreads;
+ threads += max;
// Users may call IPCThreadState::joinThreadPool directly. We don't
// currently have a way to count this directly (it could be added by
@@ -454,8 +452,8 @@
// in IPCThreadState, temporarily forget about the extra join threads.
// This is okay, because most callers of this method only care about
// having 0, 1, or more threads.
- if (mCurrentThreads > mKernelStartedThreads) {
- threads += mCurrentThreads - mKernelStartedThreads;
+ if (current > kernelStarted) {
+ threads += current - kernelStarted;
}
return threads;
@@ -463,10 +461,9 @@
// must not be initialized or maybe has poll thread setup, we
// currently don't track this in libbinder
- LOG_ALWAYS_FATAL_IF(mKernelStartedThreads != 0,
- "Expecting 0 kernel started threads but have"
- " %zu",
- mKernelStartedThreads);
+ size_t kernelStarted = mKernelStartedThreads;
+ LOG_ALWAYS_FATAL_IF(kernelStarted != 0, "Expecting 0 kernel started threads but have %zu",
+ kernelStarted);
return mCurrentThreads;
}
@@ -553,10 +550,7 @@
: mDriverName(String8(driver)),
mDriverFD(-1),
mVMStart(MAP_FAILED),
- mThreadCountLock(PTHREAD_MUTEX_INITIALIZER),
- mThreadCountDecrement(PTHREAD_COND_INITIALIZER),
mExecutingThreadsCount(0),
- mWaitingForThreads(0),
mMaxThreads(DEFAULT_MAX_BINDER_THREADS),
mCurrentThreads(0),
mKernelStartedThreads(0),