Merge "Avoid deadlock in EventThread::onNewVsyncSchedule" into udc-dev (e6cfeaad) · Commits · e / devices / smdk4412 / android_frameworks_native

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.