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Commit d39f9d46 authored by Leon Scroggins's avatar Leon Scroggins Committed by Automerger Merge Worker
Browse files

Merge "Avoid deadlock in EventThread::onNewVsyncSchedule" into udc-dev am: e6cfeaad 

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/native/+/22125708



Change-Id: Ibe1c7c0b7e3b3885dae67a58bc34bc5cbab94fb4
Signed-off-by: default avatarAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
parents b22eaaa6 e6cfeaad

services/surfaceflinger/Scheduler/Scheduler.cpp

+41 −14
Original line number Diff line number Diff line
@@ -109,7 +109,6 @@ void Scheduler::startTimers() { 
void Scheduler::setPacesetterDisplay(std::optional<PhysicalDisplayId> pacesetterIdOpt) {

    demotePacesetterDisplay();



    std::scoped_lock lock(mDisplayLock);

    promotePacesetterDisplay(pacesetterIdOpt);

}
@@ -123,16 +122,22 @@ void Scheduler::registerDisplayInternal(PhysicalDisplayId displayId, 
                                        std::shared_ptr<VsyncSchedule> vsyncSchedule) {

    demotePacesetterDisplay();



    std::shared_ptr<VsyncSchedule> pacesetterVsyncSchedule;

    {

        std::scoped_lock lock(mDisplayLock);

        mRefreshRateSelectors.emplace_or_replace(displayId, std::move(selectorPtr));

        mVsyncSchedules.emplace_or_replace(displayId, std::move(vsyncSchedule));



    promotePacesetterDisplay();

        pacesetterVsyncSchedule = promotePacesetterDisplayLocked();

    }

    applyNewVsyncSchedule(std::move(pacesetterVsyncSchedule));

}



void Scheduler::unregisterDisplay(PhysicalDisplayId displayId) {

    demotePacesetterDisplay();



    std::shared_ptr<VsyncSchedule> pacesetterVsyncSchedule;

    {

        std::scoped_lock lock(mDisplayLock);

        mRefreshRateSelectors.erase(displayId);

        mVsyncSchedules.erase(displayId);
@@ -142,7 +147,9 @@ void Scheduler::unregisterDisplay(PhysicalDisplayId displayId) { 
        // headless virtual display.)

        LOG_ALWAYS_FATAL_IF(mRefreshRateSelectors.empty(), "Cannot unregister all displays!");



    promotePacesetterDisplay();

        pacesetterVsyncSchedule = promotePacesetterDisplayLocked();

    }

    applyNewVsyncSchedule(std::move(pacesetterVsyncSchedule));

}



void Scheduler::run() {
@@ -678,6 +685,18 @@ bool Scheduler::updateFrameRateOverrides(GlobalSignals consideredSignals, Fps di 
}



void Scheduler::promotePacesetterDisplay(std::optional<PhysicalDisplayId> pacesetterIdOpt) {

    std::shared_ptr<VsyncSchedule> pacesetterVsyncSchedule;



    {

        std::scoped_lock lock(mDisplayLock);

        pacesetterVsyncSchedule = promotePacesetterDisplayLocked(pacesetterIdOpt);

    }



    applyNewVsyncSchedule(std::move(pacesetterVsyncSchedule));

}



std::shared_ptr<VsyncSchedule> Scheduler::promotePacesetterDisplayLocked(

        std::optional<PhysicalDisplayId> pacesetterIdOpt) {

    // TODO(b/241286431): Choose the pacesetter display.

    mPacesetterDisplayId = pacesetterIdOpt.value_or(mRefreshRateSelectors.begin()->first);

    ALOGI("Display %s is the pacesetter", to_string(*mPacesetterDisplayId).c_str());
@@ -697,13 +716,21 @@ void Scheduler::promotePacesetterDisplay(std::optional<PhysicalDisplayId> pacese 
        vsyncSchedule->startPeriodTransition(mSchedulerCallback, refreshRate.getPeriod(),

                                             true /* force */);

    }

    return vsyncSchedule;

}



void Scheduler::applyNewVsyncSchedule(std::shared_ptr<VsyncSchedule> vsyncSchedule) {

    onNewVsyncSchedule(vsyncSchedule->getDispatch());

    std::vector<android::EventThread*> threads;

    {

        std::lock_guard<std::mutex> lock(mConnectionsLock);

        threads.reserve(mConnections.size());

        for (auto& [_, connection] : mConnections) {

            connection.thread->onNewVsyncSchedule(vsyncSchedule);

            threads.push_back(connection.thread.get());

        }

    }

    for (auto* thread : threads) {

        thread->onNewVsyncSchedule(vsyncSchedule);

    }

}

services/surfaceflinger/Scheduler/Scheduler.h

+11 −0
Original line number Diff line number Diff line
@@ -321,7 +321,18 @@ private: 
    // Chooses a pacesetter among the registered displays, unless `pacesetterIdOpt` is specified.

    // The new `mPacesetterDisplayId` is never `std::nullopt`.

    void promotePacesetterDisplay(std::optional<PhysicalDisplayId> pacesetterIdOpt = std::nullopt)

            REQUIRES(kMainThreadContext) EXCLUDES(mDisplayLock);



    // Changes to the displays (e.g. registering and unregistering) must be made

    // while mDisplayLock is locked, and the new pacesetter then must be promoted while

    // mDisplayLock is still locked. However, a new pacesetter means that

    // MessageQueue and EventThread need to use the new pacesetter's

    // VsyncSchedule, and this must happen while mDisplayLock is *not* locked,

    // or else we may deadlock with EventThread.

    std::shared_ptr<VsyncSchedule> promotePacesetterDisplayLocked(

            std::optional<PhysicalDisplayId> pacesetterIdOpt = std::nullopt)

            REQUIRES(kMainThreadContext, mDisplayLock);

    void applyNewVsyncSchedule(std::shared_ptr<VsyncSchedule>) EXCLUDES(mDisplayLock);



    // Blocks until the pacesetter's idle timer thread exits. `mDisplayLock` must not be locked by

    // the caller on the main thread to avoid deadlock, since the timer thread locks it before exit.