Guard against racy ComposerClient reconnection (38d3da23) · Commits · e / os / android_hardware_interfaces

graphics/composer/2.1/default/Hwc.cpp

+22 −1

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@

		#include "Hwc.h"

		#include <chrono>
		#include <type_traits>
		#include <log/log.h>

		@@ -25,6 +26,8 @@
		#include "hardware/hwcomposer.h"
		#include "hwc2on1adapter/HWC2On1Adapter.h"

		using namespace std::chrono_literals;

		namespace android {
		namespace hardware {
		namespace graphics {
		@@ -218,7 +221,24 @@ Return<void> HwcHal::createClient(createClient_cb hidl_cb)
		sp<ComposerClient> client;

		{
		std::lock_guard<std::mutex> lock(mClientMutex);
		std::unique_lock<std::mutex> lock(mClientMutex);

		if (mClient != nullptr) {
		// In surface flinger we delete a composer client on one thread and
		// then create a new client on another thread. Although surface
		// flinger ensures the calls are made in that sequence (destroy and
		// then create), sometimes the calls land in the composer service
		// inverted (create and then destroy). Wait for a brief period to
		// see if the existing client is destroyed.
		ALOGI("HwcHal::createClient: Client already exists. Waiting for"
		" it to be destroyed.");
		mClientDestroyedWait.wait_for(lock, 1s,
		[this] { return mClient == nullptr; });
		std::string doneMsg = mClient == nullptr ?
		"Existing client was destroyed." :
		"Existing client was never destroyed!";
		ALOGI("HwcHal::createClient: Done waiting. %s", doneMsg.c_str());
		}

		// only one client is allowed
		if (mClient == nullptr) {
		@@ -245,6 +265,7 @@ void HwcHal::removeClient()
		{
		std::lock_guard<std::mutex> lock(mClientMutex);
		mClient = nullptr;
		mClientDestroyedWait.notify_all();
		}

		void HwcHal::hotplugHook(hwc2_callback_data_t callbackData,

graphics/composer/2.1/default/Hwc.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -17,8 +17,9 @@
		#ifndef ANDROID_HARDWARE_GRAPHICS_COMPOSER_V2_1_HWC_H
		#define ANDROID_HARDWARE_GRAPHICS_COMPOSER_V2_1_HWC_H

		#include <mutex>
		#include <condition_variable>
		#include <memory>
		#include <mutex>
		#include <unordered_set>
		#include <vector>

		@@ -211,6 +212,7 @@ private:
		} mDispatch;

		std::mutex mClientMutex;
		std::condition_variable mClientDestroyedWait;
		wp<ComposerClient> mClient;

		// If the HWC implementation version is < 2.0, use an adapter to interface