libbinder: log when threads requested, not started

Few bugs about this over the years, so adding a log for
it.

Bug: 383234630
Test: no logs added on CF boot:
    `adb logcat -d | grep "Thread pool configuration"`
Change-Id: I14382ee5d7e9cd56c245eb6d3883e7db14ff935b

3 files changed, 18 insertions, 0 deletions

diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp
index 6698d0c0cd..623e7b9139 100644
--- a/libs/binder/IPCThreadState.cpp
+++ b/libs/binder/IPCThreadState.cpp
@@ -775,6 +775,7 @@ void IPCThreadState::joinThreadPool(bool isMain)
 {
     LOG_THREADPOOL("**** THREAD %p (PID %d) IS JOINING THE THREAD POOL\n", (void*)pthread_self(),
                    getpid());
+    mProcess->checkExpectingThreadPoolStart();
     mProcess->mCurrentThreads++;
     mOut.writeInt32(isMain ? BC_ENTER_LOOPER : BC_REGISTER_LOOPER);
 
diff --git a/libs/binder/ProcessState.cpp b/libs/binder/ProcessState.cpp
index 5e7f1510bc..0e1e9b4127 100644
--- a/libs/binder/ProcessState.cpp
+++ b/libs/binder/ProcessState.cpp
@@ -501,6 +501,21 @@ bool ProcessState::isThreadPoolStarted() const {
     return mThreadPoolStarted;
 }
 
+void ProcessState::checkExpectingThreadPoolStart() const {
+    if (mThreadPoolStarted) return;
+
+    // this is also racey, but you should setup the threadpool in the main thread. If that is an
+    // issue, we can check if we are the process leader, but haven't seen the issue in practice.
+    size_t requestedThreads = mMaxThreads.load();
+
+    // if it's manually set to the default, we do ignore it here...
+    if (requestedThreads == DEFAULT_MAX_BINDER_THREADS) return;
+    if (requestedThreads == 0) return;
+
+    ALOGW("Thread pool configuration of size %zu requested, but startThreadPool was not called.",
+          requestedThreads);
+}
+
 #define DRIVER_FEATURES_PATH "/dev/binderfs/features/"
 bool ProcessState::isDriverFeatureEnabled(const DriverFeature feature) {
     // Use static variable to cache the results.
diff --git a/libs/binder/include/binder/ProcessState.h b/libs/binder/include/binder/ProcessState.h
index 21bfd42fcc..ced49c19c2 100644
--- a/libs/binder/include/binder/ProcessState.h
+++ b/libs/binder/include/binder/ProcessState.h
@@ -141,6 +141,8 @@ public:
 private:
     static sp<ProcessState> init(const char* defaultDriver, bool requireDefault);
 
+    void checkExpectingThreadPoolStart() const;
+
     static void onFork();
     static void parentPostFork();
     static void childPostFork();