commit d62b89be28994b5be57b0b1587e201a11b99c97e
author Steven Moreland <smoreland@google.com> Wed Mar 22 21:05:13 2023 +0000
committer Steven Moreland <smoreland@google.com> Wed Mar 22 21:08:50 2023 +0000
tree 568d7e4635690a9464b9f2f5ce913117186cd576
parent 00be693277ce4d26ab98589abb01ac5a628cb835

libbinderthreadstateutils: don't init binder

Don't initialize binder/hwbinder thread state if they
aren't already initialized. This is fine - if we
know they aren't initialized, then there is no binder
call going.

Bug: 205282403
Test: libbinderthreadstateutils_test
TesT: binderRpcTest (because it uses these APIs in a special way)
Change-Id: Id67010bb15559e85dd764746525562acc7e1f13c

libs/binderthreadstate/include/binderthreadstate/CallerUtils.h

diff --git a/libs/binderthreadstate/include/binderthreadstate/CallerUtils.h b/libs/binderthreadstate/include/binderthreadstate/CallerUtils.h
index a3e5026..54259d2 100644
--- a/libs/binderthreadstate/include/binderthreadstate/CallerUtils.h
+++ b/libs/binderthreadstate/include/binderthreadstate/CallerUtils.h
@@ -36,8 +36,12 @@
 // Based on where we are in recursion of nested binder/hwbinder calls, determine
 // which one we are closer to.
 inline static BinderCallType getCurrentServingCall() {
-    const void* hwbinderSp = android::hardware::IPCThreadState::self()->getServingStackPointer();
-    const void* binderSp = android::IPCThreadState::self()->getServingStackPointer();
+    auto* hwState = android::hardware::IPCThreadState::selfOrNull();
+    auto* state = android::IPCThreadState::selfOrNull();
+
+    // getServingStackPointer can also return nullptr
+    const void* hwbinderSp = hwState ? hwState->getServingStackPointer() : nullptr;
+    const void* binderSp = state ? state->getServingStackPointer() : nullptr;
 
     if (hwbinderSp == nullptr && binderSp == nullptr) return BinderCallType::NONE;
     if (hwbinderSp == nullptr) return BinderCallType::BINDER;

libs/binderthreadstate/test.cpp

diff --git a/libs/binderthreadstate/test.cpp b/libs/binderthreadstate/test.cpp
index df1f35d..b5c4010 100644
--- a/libs/binderthreadstate/test.cpp
+++ b/libs/binderthreadstate/test.cpp
@@ -16,11 +16,16 @@
 
 #include <BnAidlStuff.h>
 #include <android-base/logging.h>
+#include <binder/IPCThreadState.h>
 #include <binder/IServiceManager.h>
 #include <binderthreadstate/CallerUtils.h>
 #include <binderthreadstateutilstest/1.0/IHidlStuff.h>
 #include <gtest/gtest.h>
 #include <hidl/HidlTransportSupport.h>
+#include <hwbinder/IPCThreadState.h>
+
+#include <thread>
+
 #include <linux/prctl.h>
 #include <sys/prctl.h>
 
@@ -154,6 +159,20 @@
     EXPECT_TRUE(server->callLocal().isOk());
 }
 
+TEST(BinderThreadState, DoesntInitializeBinderDriver) {
+    // this is on another thread, because it's testing thread-specific
+    // state and we expect it not to be initialized.
+    std::thread([&] {
+        EXPECT_EQ(nullptr, android::IPCThreadState::selfOrNull());
+        EXPECT_EQ(nullptr, android::hardware::IPCThreadState::selfOrNull());
+
+        (void)getCurrentServingCall();
+
+        EXPECT_EQ(nullptr, android::IPCThreadState::selfOrNull());
+        EXPECT_EQ(nullptr, android::hardware::IPCThreadState::selfOrNull());
+    }).join();
+}
+
 TEST(BindThreadState, RemoteHidlCall) {
     auto stuff = IHidlStuff::getService(id2name(kP1Id));
     ASSERT_NE(nullptr, stuff);