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init: Fix signalfd support in WaitToBeReaped()

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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: Bart Van Assche <bvanassche@google.com>
This commit is contained in:
Bart Van Assche 2023-11-16 11:19:08 -08:00
parent c93c5eff0e
commit 1daf88d6ce
1 changed files with 28 additions and 13 deletions
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41
init/sigchld_handler.cpp
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@ -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)) {
@ -151,22 +151,37 @@ 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); });
}
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;
}
if (sigchld_fd >= 0) {
epoll.Wait(std::max(timeout - t.duration(), 0ms));
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;
}
} else {
std::this_thread::sleep_for(50ms);
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) {
auto result = epoll.Wait(std::max(timeout - t.duration(), 0ms));
if (result.ok()) {
ReapAndRemove(alive_pids);
continue;
} else {
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";
for (pid_t pid : alive_pids) {