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Commit 1daf88d6 authored by Bart Van Assche's avatar Bart Van Assche
Browse files

init: Fix signalfd support in WaitToBeReaped() 



Add an Epoll::Open() call such that the Epoll::Wait() calls wait for the
signalfd. Rename DiscardSiginfo() into HandleSignal(). Handle Epoll method
call failures. Test whether alive_pids is empty once per loop iteration.

Test: CtsInitTestCases:ServiceStopTest
Change-Id: I16c27aa74d61f889b304f3e59cd3c5255c299ce1
Signed-off-by: default avatarBart Van Assche <bvanassche@google.com>
parent c93c5eff

init/sigchld_handler.cpp

+26 −11
Original line number Diff line number Diff line
@@ -138,7 +138,7 @@ static void ReapAndRemove(std::vector<pid_t>& alive_pids) { 
    }

}



static void DiscardSiginfo(int signal_fd) {

static void HandleSignal(int signal_fd) {

    signalfd_siginfo siginfo;

    ssize_t bytes_read = TEMP_FAILURE_RETRY(read(signal_fd, &siginfo, sizeof(siginfo)));

    if (bytes_read != sizeof(siginfo)) {
@@ -151,21 +151,36 @@ void WaitToBeReaped(int sigchld_fd, const std::vector<pid_t>& pids, 
                    std::chrono::milliseconds timeout) {

    Timer t;

    Epoll epoll;

    // The init process passes a valid sigchld_fd argument but unit tests do not.

    if (sigchld_fd >= 0) {

        epoll.RegisterHandler(sigchld_fd, [sigchld_fd]() { DiscardSiginfo(sigchld_fd); });

        if (auto result = epoll.Open(); result.ok()) {

            result =

                    epoll.RegisterHandler(sigchld_fd, [sigchld_fd]() { HandleSignal(sigchld_fd); });

            if (!result.ok()) {

                LOG(WARNING) << __func__

                             << " RegisterHandler() failed. Falling back to sleep_for(): "

                             << result.error();

                sigchld_fd = -1;

            }

    std::vector<pid_t> alive_pids(pids.begin(), pids.end());

    while (!alive_pids.empty() && t.duration() < timeout) {

        ReapAndRemove(alive_pids);

        if (alive_pids.empty()) {

            break;

        } else {

            LOG(WARNING) << __func__ << " Epoll::Open() failed. Falling back to sleep_for(): "

                         << result.error();

            sigchld_fd = -1;

        }

    }

    std::vector<pid_t> alive_pids(pids);

    ReapAndRemove(alive_pids);

    while (!alive_pids.empty() && t.duration() < timeout) {

        if (sigchld_fd >= 0) {

            epoll.Wait(std::max(timeout - t.duration(), 0ms));

            auto result = epoll.Wait(std::max(timeout - t.duration(), 0ms));

            if (result.ok()) {

                ReapAndRemove(alive_pids);

                continue;

            } else {

            std::this_thread::sleep_for(50ms);

                LOG(WARNING) << "Epoll::Wait() failed " << result.error();

            }

        }

        std::this_thread::sleep_for(50ms);

        ReapAndRemove(alive_pids);

    }

    LOG(INFO) << "Waiting for " << pids.size() << " pids to be reaped took " << t << " with "

              << alive_pids.size() << " of them still running";