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Commit 1e19ac97 authored by Ady Abraham's avatar Ady Abraham
Browse files

SurfaceFlinger: fix OneShotTimer timespec overflow 

struct timespec::tv_nsec must be < 1s to be considered as valid
input to sem_clockwait.

Test: interact with device and observe systraces
Bug: 170665374
Change-Id: I4aa5b86cd55fd89adb12cd5a28ce599c8a1c0c93
parent b8871072

services/surfaceflinger/Scheduler/OneShotTimer.cpp

+25 −9
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 


#include "OneShotTimer.h"



#include <utils/Log.h>

#include <utils/Timers.h>

#include <chrono>

#include <sstream>

#include <thread>
@@ -29,9 +31,9 @@ constexpr int64_t kNsToSeconds = std::chrono::duration_cast<std::chrono::nanosec 
// (tv_sec) is the whole count of seconds. The second (tv_nsec) is the

// nanosecond part of the count. This function takes care of translation.

void calculateTimeoutTime(std::chrono::nanoseconds timestamp, timespec* spec) {

    clock_gettime(CLOCK_MONOTONIC, spec);

    spec->tv_sec += static_cast<__kernel_time_t>(timestamp.count() / kNsToSeconds);

    spec->tv_nsec += timestamp.count() % kNsToSeconds;

    const nsecs_t timeout = systemTime(CLOCK_MONOTONIC) + timestamp.count();

    spec->tv_sec = static_cast<__kernel_time_t>(timeout / kNsToSeconds);

    spec->tv_nsec = timeout % kNsToSeconds;

}

} // namespace
@@ -47,7 +49,8 @@ OneShotTimer::~OneShotTimer() { 
}



void OneShotTimer::start() {

    sem_init(&mSemaphore, 0, 0);

    int result = sem_init(&mSemaphore, 0, 0);

    LOG_ALWAYS_FATAL_IF(result, "sem_init failed");



    if (!mThread.joinable()) {

        // Only create thread if it has not been created.
@@ -57,11 +60,13 @@ void OneShotTimer::start() { 


void OneShotTimer::stop() {

    mStopTriggered = true;

    sem_post(&mSemaphore);

    int result = sem_post(&mSemaphore);

    LOG_ALWAYS_FATAL_IF(result, "sem_post failed");



    if (mThread.joinable()) {

        mThread.join();

        sem_destroy(&mSemaphore);

        result = sem_destroy(&mSemaphore);

        LOG_ALWAYS_FATAL_IF(result, "sem_destroy failed");

    }

}
@@ -77,7 +82,12 @@ void OneShotTimer::loop() { 
        }



        if (state == TimerState::IDLE) {

            sem_wait(&mSemaphore);

            int result = sem_wait(&mSemaphore);

            if (result && errno != EINTR) {

                std::stringstream ss;

                ss << "sem_wait failed (" << errno << ")";

                LOG_ALWAYS_FATAL("%s", ss.str().c_str());

            }

            continue;

        }
@@ -101,7 +111,12 @@ void OneShotTimer::loop() { 
            // Wait for mInterval time for semaphore signal.

            struct timespec ts;

            calculateTimeoutTime(std::chrono::nanoseconds(mInterval), &ts);

            sem_clockwait(&mSemaphore, CLOCK_MONOTONIC, &ts);

            int result = sem_clockwait(&mSemaphore, CLOCK_MONOTONIC, &ts);

            if (result && errno != ETIMEDOUT && errno != EINTR) {

                std::stringstream ss;

                ss << "sem_clockwait failed (" << errno << ")";

                LOG_ALWAYS_FATAL("%s", ss.str().c_str());

            }



            state = checkForResetAndStop(state);

            if (state == TimerState::RESET) {
@@ -135,7 +150,8 @@ OneShotTimer::TimerState OneShotTimer::checkForResetAndStop(TimerState state) { 


void OneShotTimer::reset() {

    mResetTriggered = true;

    sem_post(&mSemaphore);

    int result = sem_post(&mSemaphore);

    LOG_ALWAYS_FATAL_IF(result, "sem_post failed");

}



std::string OneShotTimer::dump() const {