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Commit ffa3aaac authored by Andrei Homescu's avatar Andrei Homescu
Browse files

libbinder: add build option for single-threaded RPC 

Trusty does not support threading. This adds a build option
to disable mutexes and other threading code from RpcState,
RpcSession, and RpcServer.

Bug: 224644083
Test: build Trusty
Change-Id: Iaa78caca1ddee45be7c2def2755598decc0d4d15
parent 992a405f

libs/binder/BuildFlags.h

0 → 100644
+25 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2022 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



namespace android {



#ifdef BINDER_RPC_SINGLE_THREADED

constexpr bool kEnableRpcThreads = false;

#else

constexpr bool kEnableRpcThreads = true;

#endif



} // namespace android

libs/binder/FdTrigger.cpp

+24 −2
Original line number Diff line number Diff line
@@ -28,25 +28,45 @@ namespace android { 


std::unique_ptr<FdTrigger> FdTrigger::make() {

    auto ret = std::make_unique<FdTrigger>();

#ifndef BINDER_RPC_SINGLE_THREADED

    if (!android::base::Pipe(&ret->mRead, &ret->mWrite)) {

        ALOGE("Could not create pipe %s", strerror(errno));

        return nullptr;

    }

#endif

    return ret;

}



void FdTrigger::trigger() {

#ifdef BINDER_RPC_SINGLE_THREADED

    mTriggered = true;

#else

    mWrite.reset();

#endif

}



bool FdTrigger::isTriggered() {

#ifdef BINDER_RPC_SINGLE_THREADED

    return mTriggered;

#else

    return mWrite == -1;

#endif

}



status_t FdTrigger::triggerablePoll(base::borrowed_fd fd, int16_t event) {

#ifdef BINDER_RPC_SINGLE_THREADED

    if (mTriggered) {

        return DEAD_OBJECT;

    }

#endif



    LOG_ALWAYS_FATAL_IF(event == 0, "triggerablePoll %d with event 0 is not allowed", fd.get());

    pollfd pfd[]{{.fd = fd.get(), .events = static_cast<int16_t>(event), .revents = 0},

                 {.fd = mRead.get(), .events = 0, .revents = 0}};

    pollfd pfd[]{

            {.fd = fd.get(), .events = static_cast<int16_t>(event), .revents = 0},

#ifndef BINDER_RPC_SINGLE_THREADED

            {.fd = mRead.get(), .events = 0, .revents = 0},

#endif

    };

    int ret = TEMP_FAILURE_RETRY(poll(pfd, arraysize(pfd), -1));

    if (ret < 0) {

        return -errno;
@@ -55,6 +75,7 @@ status_t FdTrigger::triggerablePoll(base::borrowed_fd fd, int16_t event) { 


    // At least one FD has events. Check them.



#ifndef BINDER_RPC_SINGLE_THREADED

    // Detect explicit trigger(): DEAD_OBJECT

    if (pfd[1].revents & POLLHUP) {

        return DEAD_OBJECT;
@@ -68,6 +89,7 @@ status_t FdTrigger::triggerablePoll(base::borrowed_fd fd, int16_t event) { 


    // pfd[1].revents is 0, hence pfd[0].revents must be set, and only possible values are

    // a subset of event | POLLHUP | POLLERR | POLLNVAL.

#endif



    // POLLNVAL: invalid FD number, e.g. not opened.

    if (pfd[0].revents & POLLNVAL) {

libs/binder/FdTrigger.h

+4 −0
Original line number Diff line number Diff line
@@ -55,7 +55,11 @@ public: 
    [[nodiscard]] status_t triggerablePoll(base::borrowed_fd fd, int16_t event);



private:

#ifdef BINDER_RPC_SINGLE_THREADED

    bool mTriggered = false;

#else

    base::unique_fd mWrite;

    base::unique_fd mRead;

#endif

};

} // namespace android

libs/binder/RpcServer.cpp

+42 −26
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <log/log.h>

#include <utils/Compat.h>



#include "BuildFlags.h"

#include "FdTrigger.h"

#include "RpcSocketAddress.h"

#include "RpcState.h"
@@ -131,27 +132,27 @@ void RpcServer::setSupportedFileDescriptorTransportModes( 
}



void RpcServer::setRootObject(const sp<IBinder>& binder) {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    mRootObjectFactory = nullptr;

    mRootObjectWeak = mRootObject = binder;

}



void RpcServer::setRootObjectWeak(const wp<IBinder>& binder) {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    mRootObject.clear();

    mRootObjectFactory = nullptr;

    mRootObjectWeak = binder;

}

void RpcServer::setPerSessionRootObject(

        std::function<sp<IBinder>(const void*, size_t)>&& makeObject) {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    mRootObject.clear();

    mRootObjectWeak.clear();

    mRootObjectFactory = std::move(makeObject);

}



sp<IBinder> RpcServer::getRootObject() {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    bool hasWeak = mRootObjectWeak.unsafe_get();

    sp<IBinder> ret = mRootObjectWeak.promote();

    ALOGW_IF(hasWeak && ret == nullptr, "RpcServer root object is freed, returning nullptr");
@@ -159,7 +160,7 @@ sp<IBinder> RpcServer::getRootObject() { 
}



std::vector<uint8_t> RpcServer::getCertificate(RpcCertificateFormat format) {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    return mCtx->getCertificate(format);

}
@@ -168,15 +169,17 @@ static void joinRpcServer(sp<RpcServer>&& thiz) { 
}



void RpcServer::start() {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    LOG_ALWAYS_FATAL_IF(mJoinThread.get(), "Already started!");

    mJoinThread = std::make_unique<std::thread>(&joinRpcServer, sp<RpcServer>::fromExisting(this));

    mJoinThread =

            std::make_unique<RpcMaybeThread>(&joinRpcServer, sp<RpcServer>::fromExisting(this));

    rpcJoinIfSingleThreaded(*mJoinThread);

}



void RpcServer::join() {



    {

        std::lock_guard<std::mutex> _l(mLock);

        RpcMutexLockGuard _l(mLock);

        LOG_ALWAYS_FATAL_IF(!mServer.ok(), "RpcServer must be setup to join.");

        LOG_ALWAYS_FATAL_IF(mShutdownTrigger != nullptr, "Already joined");

        mJoinThreadRunning = true;
@@ -204,24 +207,31 @@ void RpcServer::join() { 
        LOG_RPC_DETAIL("accept4 on fd %d yields fd %d", mServer.get(), clientFd.get());



        {

            std::lock_guard<std::mutex> _l(mLock);

            std::thread thread =

                    std::thread(&RpcServer::establishConnection, sp<RpcServer>::fromExisting(this),

            RpcMutexLockGuard _l(mLock);

            RpcMaybeThread thread = RpcMaybeThread(&RpcServer::establishConnection,

                                                   sp<RpcServer>::fromExisting(this),

                                                   std::move(clientFd), addr, addrLen);

            mConnectingThreads[thread.get_id()] = std::move(thread);



            auto& threadRef = mConnectingThreads[thread.get_id()];

            threadRef = std::move(thread);

            rpcJoinIfSingleThreaded(threadRef);

        }

    }

    LOG_RPC_DETAIL("RpcServer::join exiting with %s", statusToString(status).c_str());



    {

        std::lock_guard<std::mutex> _l(mLock);

    if constexpr (kEnableRpcThreads) {

        RpcMutexLockGuard _l(mLock);

        mJoinThreadRunning = false;

    } else {

        // Multi-threaded builds clear this in shutdown(), but we need it valid

        // so the loop above exits cleanly

        mShutdownTrigger = nullptr;

    }

    mShutdownCv.notify_all();

}



bool RpcServer::shutdown() {

    std::unique_lock<std::mutex> _l(mLock);

    RpcMutexUniqueLock _l(mLock);

    if (mShutdownTrigger == nullptr) {

        LOG_RPC_DETAIL("Cannot shutdown. No shutdown trigger installed (already shutdown?)");

        return false;
@@ -232,10 +242,16 @@ bool RpcServer::shutdown() { 
    for (auto& [id, session] : mSessions) {

        (void)id;

        // server lock is a more general lock

        std::lock_guard<std::mutex> _lSession(session->mMutex);

        RpcMutexLockGuard _lSession(session->mMutex);

        session->mShutdownTrigger->trigger();

    }



    if constexpr (!kEnableRpcThreads) {

        // In single-threaded mode we're done here, everything else that

        // needs to happen should be at the end of RpcServer::join()

        return true;

    }



    while (mJoinThreadRunning || !mConnectingThreads.empty() || !mSessions.empty()) {

        if (std::cv_status::timeout == mShutdownCv.wait_for(_l, std::chrono::seconds(1))) {

            ALOGE("Waiting for RpcServer to shut down (1s w/o progress). Join thread running: %d, "
@@ -263,7 +279,7 @@ bool RpcServer::shutdown() { 
}



std::vector<sp<RpcSession>> RpcServer::listSessions() {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    std::vector<sp<RpcSession>> sessions;

    for (auto& [id, session] : mSessions) {

        (void)id;
@@ -273,7 +289,7 @@ std::vector<sp<RpcSession>> RpcServer::listSessions() { 
}



size_t RpcServer::numUninitializedSessions() {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    return mConnectingThreads.size();

}
@@ -354,12 +370,12 @@ void RpcServer::establishConnection(sp<RpcServer>&& server, base::unique_fd clie 
        }

    }



    std::thread thisThread;

    RpcMaybeThread thisThread;

    sp<RpcSession> session;

    {

        std::unique_lock<std::mutex> _l(server->mLock);

        RpcMutexUniqueLock _l(server->mLock);



        auto threadId = server->mConnectingThreads.find(std::this_thread::get_id());

        auto threadId = server->mConnectingThreads.find(rpc_this_thread::get_id());

        LOG_ALWAYS_FATAL_IF(threadId == server->mConnectingThreads.end(),

                            "Must establish connection on owned thread");

        thisThread = std::move(threadId->second);
@@ -505,7 +521,7 @@ void RpcServer::onSessionAllIncomingThreadsEnded(const sp<RpcSession>& session) 
    LOG_RPC_DETAIL("Dropping session with address %s",

                   base::HexString(id.data(), id.size()).c_str());



    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    auto it = mSessions.find(id);

    LOG_ALWAYS_FATAL_IF(it == mSessions.end(), "Bad state, unknown session id %s",

                        base::HexString(id.data(), id.size()).c_str());
@@ -519,17 +535,17 @@ void RpcServer::onSessionIncomingThreadEnded() { 
}



bool RpcServer::hasServer() {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    return mServer.ok();

}



unique_fd RpcServer::releaseServer() {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    return std::move(mServer);

}



status_t RpcServer::setupExternalServer(base::unique_fd serverFd) {

    std::lock_guard<std::mutex> _l(mLock);

    RpcMutexLockGuard _l(mLock);

    if (mServer.ok()) {

        ALOGE("Each RpcServer can only have one server.");

        return INVALID_OPERATION;

libs/binder/RpcSession.cpp

+36 −31
Original line number Diff line number Diff line
@@ -21,7 +21,6 @@ 
#include <dlfcn.h>

#include <inttypes.h>

#include <poll.h>

#include <pthread.h>

#include <unistd.h>



#include <string_view>
@@ -60,7 +59,7 @@ RpcSession::RpcSession(std::unique_ptr<RpcTransportCtx> ctx) : mCtx(std::move(ct 
RpcSession::~RpcSession() {

    LOG_RPC_DETAIL("RpcSession destroyed %p", this);



    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);

    LOG_ALWAYS_FATAL_IF(mConnections.mIncoming.size() != 0,

                        "Should not be able to destroy a session with servers in use.");

}
@@ -77,7 +76,7 @@ sp<RpcSession> RpcSession::make(std::unique_ptr<RpcTransportCtxFactory> rpcTrans 
}



void RpcSession::setMaxIncomingThreads(size_t threads) {

    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);

    LOG_ALWAYS_FATAL_IF(!mConnections.mOutgoing.empty() || !mConnections.mIncoming.empty(),

                        "Must set max incoming threads before setting up connections, but has %zu "

                        "client(s) and %zu server(s)",
@@ -86,12 +85,12 @@ void RpcSession::setMaxIncomingThreads(size_t threads) { 
}



size_t RpcSession::getMaxIncomingThreads() {

    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);

    return mMaxIncomingThreads;

}



void RpcSession::setMaxOutgoingThreads(size_t threads) {

    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);

    LOG_ALWAYS_FATAL_IF(!mConnections.mOutgoing.empty() || !mConnections.mIncoming.empty(),

                        "Must set max outgoing threads before setting up connections, but has %zu "

                        "client(s) and %zu server(s)",
@@ -100,7 +99,7 @@ void RpcSession::setMaxOutgoingThreads(size_t threads) { 
}



size_t RpcSession::getMaxOutgoingThreads() {

    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);

    return mMaxOutgoingThreads;

}
@@ -113,7 +112,7 @@ bool RpcSession::setProtocolVersion(uint32_t version) { 
        return false;

    }



    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);

    if (mProtocolVersion && version > *mProtocolVersion) {

        ALOGE("Cannot upgrade explicitly capped protocol version %u to newer version %u",

              *mProtocolVersion, version);
@@ -125,7 +124,7 @@ bool RpcSession::setProtocolVersion(uint32_t version) { 
}



std::optional<uint32_t> RpcSession::getProtocolVersion() {

    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);

    return mProtocolVersion;

}
@@ -209,7 +208,7 @@ status_t RpcSession::getRemoteMaxThreads(size_t* maxThreads) { 
}



bool RpcSession::shutdownAndWait(bool wait) {

    std::unique_lock<std::mutex> _l(mMutex);

    RpcMutexUniqueLock _l(mMutex);

    LOG_ALWAYS_FATAL_IF(mShutdownTrigger == nullptr, "Shutdown trigger not installed");



    mShutdownTrigger->trigger();
@@ -222,6 +221,7 @@ bool RpcSession::shutdownAndWait(bool wait) { 
    }



    _l.unlock();



    mRpcBinderState->clear();



    return true;
@@ -256,7 +256,7 @@ status_t RpcSession::sendDecStrongToTarget(uint64_t address, size_t target) { 


status_t RpcSession::readId() {

    {

        std::lock_guard<std::mutex> _l(mMutex);

        RpcMutexLockGuard _l(mMutex);

        LOG_ALWAYS_FATAL_IF(mForServer != nullptr, "Can only update ID for client.");

    }
@@ -282,7 +282,7 @@ void RpcSession::WaitForShutdownListener::onSessionIncomingThreadEnded() { 
    mCv.notify_all();

}



void RpcSession::WaitForShutdownListener::waitForShutdown(std::unique_lock<std::mutex>& lock,

void RpcSession::WaitForShutdownListener::waitForShutdown(RpcMutexUniqueLock& lock,

                                                          const sp<RpcSession>& session) {

    while (session->mConnections.mIncoming.size() > 0) {

        if (std::cv_status::timeout == mCv.wait_for(lock, std::chrono::seconds(1))) {
@@ -293,11 +293,11 @@ void RpcSession::WaitForShutdownListener::waitForShutdown(std::unique_lock<std:: 
    }

}



void RpcSession::preJoinThreadOwnership(std::thread thread) {

    LOG_ALWAYS_FATAL_IF(thread.get_id() != std::this_thread::get_id(), "Must own this thread");

void RpcSession::preJoinThreadOwnership(RpcMaybeThread thread) {

    LOG_ALWAYS_FATAL_IF(thread.get_id() != rpc_this_thread::get_id(), "Must own this thread");



    {

        std::lock_guard<std::mutex> _l(mMutex);

        RpcMutexLockGuard _l(mMutex);

        mConnections.mThreads[thread.get_id()] = std::move(thread);

    }

}
@@ -404,8 +404,8 @@ void RpcSession::join(sp<RpcSession>&& session, PreJoinSetupResult&& setupResult 


    sp<RpcSession::EventListener> listener;

    {

        std::lock_guard<std::mutex> _l(session->mMutex);

        auto it = session->mConnections.mThreads.find(std::this_thread::get_id());

        RpcMutexLockGuard _l(session->mMutex);

        auto it = session->mConnections.mThreads.find(rpc_this_thread::get_id());

        LOG_ALWAYS_FATAL_IF(it == session->mConnections.mThreads.end());

        it->second.detach();

        session->mConnections.mThreads.erase(it);
@@ -438,7 +438,7 @@ sp<RpcServer> RpcSession::server() { 
status_t RpcSession::setupClient(const std::function<status_t(const std::vector<uint8_t>& sessionId,

                                                              bool incoming)>& connectAndInit) {

    {

        std::lock_guard<std::mutex> _l(mMutex);

        RpcMutexLockGuard _l(mMutex);

        LOG_ALWAYS_FATAL_IF(mConnections.mOutgoing.size() != 0,

                            "Must only setup session once, but already has %zu clients",

                            mConnections.mOutgoing.size());
@@ -500,7 +500,11 @@ status_t RpcSession::setupClient(const std::function<status_t(const std::vector< 
        return status;

    }



#ifdef BINDER_RPC_SINGLE_THREADED

    constexpr size_t outgoingThreads = 1;

#else  // BINDER_RPC_SINGLE_THREADED

    size_t outgoingThreads = std::min(numThreadsAvailable, mMaxOutgoingThreads);

#endif // BINDER_RPC_SINGLE_THREADED

    ALOGI_IF(outgoingThreads != numThreadsAvailable,

             "Server hints client to start %zu outgoing threads, but client will only start %zu "

             "because it is preconfigured to start at most %zu outgoing threads.",
@@ -655,14 +659,14 @@ status_t RpcSession::initAndAddConnection(unique_fd fd, const std::vector<uint8_ 
}



status_t RpcSession::addIncomingConnection(std::unique_ptr<RpcTransport> rpcTransport) {

    std::mutex mutex;

    std::condition_variable joinCv;

    std::unique_lock<std::mutex> lock(mutex);

    std::thread thread;

    RpcMutex mutex;

    RpcConditionVariable joinCv;

    RpcMutexUniqueLock lock(mutex);

    RpcMaybeThread thread;

    sp<RpcSession> thiz = sp<RpcSession>::fromExisting(this);

    bool ownershipTransferred = false;

    thread = std::thread([&]() {

        std::unique_lock<std::mutex> threadLock(mutex);

    thread = RpcMaybeThread([&]() {

        RpcMutexUniqueLock threadLock(mutex);

        std::unique_ptr<RpcTransport> movedRpcTransport = std::move(rpcTransport);

        // NOLINTNEXTLINE(performance-unnecessary-copy-initialization)

        sp<RpcSession> session = thiz;
@@ -678,6 +682,7 @@ status_t RpcSession::addIncomingConnection(std::unique_ptr<RpcTransport> rpcTran 


        RpcSession::join(std::move(session), std::move(setupResult));

    });

    rpcJoinIfSingleThreaded(thread);

    joinCv.wait(lock, [&] { return ownershipTransferred; });

    LOG_ALWAYS_FATAL_IF(!ownershipTransferred);

    return OK;
@@ -697,9 +702,9 @@ status_t RpcSession::initShutdownTrigger() { 
status_t RpcSession::addOutgoingConnection(std::unique_ptr<RpcTransport> rpcTransport, bool init) {

    sp<RpcConnection> connection = sp<RpcConnection>::make();

    {

        std::lock_guard<std::mutex> _l(mMutex);

        RpcMutexLockGuard _l(mMutex);

        connection->rpcTransport = std::move(rpcTransport);

        connection->exclusiveTid = base::GetThreadId();

        connection->exclusiveTid = rpcGetThreadId();

        mConnections.mOutgoing.push_back(connection);

    }
@@ -736,7 +741,7 @@ bool RpcSession::setForServer(const wp<RpcServer>& server, const wp<EventListene 


sp<RpcSession::RpcConnection> RpcSession::assignIncomingConnectionToThisThread(

        std::unique_ptr<RpcTransport> rpcTransport) {

    std::lock_guard<std::mutex> _l(mMutex);

    RpcMutexLockGuard _l(mMutex);



    if (mConnections.mIncoming.size() >= mMaxIncomingThreads) {

        ALOGE("Cannot add thread to session with %zu threads (max is set to %zu)",
@@ -754,7 +759,7 @@ sp<RpcSession::RpcConnection> RpcSession::assignIncomingConnectionToThisThread( 


    sp<RpcConnection> session = sp<RpcConnection>::make();

    session->rpcTransport = std::move(rpcTransport);

    session->exclusiveTid = base::GetThreadId();

    session->exclusiveTid = rpcGetThreadId();



    mConnections.mIncoming.push_back(session);

    mConnections.mMaxIncoming = mConnections.mIncoming.size();
@@ -763,7 +768,7 @@ sp<RpcSession::RpcConnection> RpcSession::assignIncomingConnectionToThisThread( 
}



bool RpcSession::removeIncomingConnection(const sp<RpcConnection>& connection) {

    std::unique_lock<std::mutex> _l(mMutex);

    RpcMutexUniqueLock _l(mMutex);

    if (auto it =

                std::find(mConnections.mIncoming.begin(), mConnections.mIncoming.end(), connection);

        it != mConnections.mIncoming.end()) {
@@ -781,7 +786,7 @@ bool RpcSession::removeIncomingConnection(const sp<RpcConnection>& connection) { 
}



void RpcSession::clearConnectionTid(const sp<RpcConnection>& connection) {

    std::unique_lock<std::mutex> _l(mMutex);

    RpcMutexUniqueLock _l(mMutex);

    connection->exclusiveTid = std::nullopt;

    if (mConnections.mWaitingThreads > 0) {

        _l.unlock();
@@ -799,8 +804,8 @@ status_t RpcSession::ExclusiveConnection::find(const sp<RpcSession>& session, Co 
    connection->mConnection = nullptr;

    connection->mReentrant = false;



    uint64_t tid = base::GetThreadId();

    std::unique_lock<std::mutex> _l(session->mMutex);

    uint64_t tid = rpcGetThreadId();

    RpcMutexUniqueLock _l(session->mMutex);



    session->mConnections.mWaitingThreads++;

    while (true) {