fcontext can't work in mips64

[pkngpkng]

• source

#include <boost/fiber/all.hpp>
#include <chrono>
#include <functional>
#include <memory>
#include <thread>

class ThreadExecutor {
public:
  ThreadExecutor()
      : m_channel(std::make_unique<
                  boost::fibers::buffered_channel<std::function<void()>>>(
            s_stackMaxCount)) {
    std::promise<void> result;
    m_thread = std::make_unique<std::thread>([this, &result] {
      auto allocator = boost::fibers::pooled_fixedsize_stack(s_stackSize);

      result.set_value();
      std::function<void()> task;
      while (boost::fibers::channel_op_status::closed != m_channel->pop(task)) {
        --m_count;
        boost::fibers::fiber{
            std::allocator_arg, allocator,
            [task = std::move(task), stackSize = s_stackSize]() { task(); }}
            .detach();
      }
    });
    result.get_future().get();
  }

  ~ThreadExecutor() noexcept {
    if (!m_channel->is_closed()) {
      m_channel->close();
    }
    if (m_thread->joinable()) {
      m_thread->join();
    }
  }

  void Stop() {
    if (!m_channel->is_closed()) {
      m_channel->close();
    }
  }

  void Join() {
    if (m_thread->joinable()) {
      m_thread->join();
    }
  }

  void PostTask(const std::function<void()> &task) {
    const auto ret = m_channel->try_push(task);
    switch (ret) {
    case boost::fibers::channel_op_status::success:
      /* likely path */
      ++m_count;
      break;
    case boost::fibers::channel_op_status::full:
      break;
    case boost::fibers::channel_op_status::closed:
      break;
    default:
      return;
    }
    return;
  }

private:
  const size_t s_stackSize = 256 * 1024;
  const size_t s_stackMaxCount = 1024;
  std::unique_ptr<boost::fibers::buffered_channel<std::function<void()>>>
      m_channel;
  std::atomic_int m_count;
  std::unique_ptr<std::thread> m_thread;
};

int main() {
  ThreadExecutor executor;

  std::promise<void> p1;
  std::promise<void> p2;
  printf("fiber task post \r\n");
  executor.PostTask([&] {
    printf("fiber task1 start \r\n");
    boost::fibers::promise<void> promise;
    std::thread t([&] {
      printf("std thread1 task start \r\n");
      std::this_thread::sleep_for(std::chrono::seconds(5));
      printf("std thread1 task stop \r\n");
      promise.set_value();
    });
    printf("fiber task1 sleep \r\n");
    promise.get_future().get();
    printf("fiber task1 stop \r\n");
    p1.set_value();
  });
  executor.PostTask([&] {
    printf("fiber task2 start \r\n");
    boost::fibers::promise<void> promise;
    std::thread t([&] {
      printf("std thread task2 start \r\n");
      std::this_thread::sleep_for(std::chrono::seconds(5));
      printf("std thread task2 stop \r\n");
      promise.set_value();
    });
    printf("fiber task2 sleep \r\n");
    promise.get_future().get();
    printf("fiber task2 stop \r\n");
    p2.set_value();
  });

  p1.get_future().get();
  p2.get_future().get();
  return 0;
}

• result

root@debian-mips64el:~# ./test_fiber 
fiber task post 
fiber task1 start 
std thread1 task start 
fiber task1 sleep 
fiber task2 start 
fiber task2 sleep 
[ 3716.428377] do_page_fault(): sending SIGSEGV to test_fiber for invalid read access from 0000000000000010
[ 3716.436963] epc = 0000000000000011 in test_fiber[aaab270000+51000]
[ 3716.439123] ra  = 0000000000000011 in test_fiber[aaab270000+51000]
std thread task2 start 
Segmentation fault

It will crash at promise.get_future().get(); returns;

[olk]

MIPS64 support was provided by other developers - I do not have access to this platform.
It would be nice if you could provide a fix via pull-request.

[olk]

should work now, see regression tests for mips64el on buster

[pkngpkng]

@olk I test the same example with boost 1.81.0 in Loongson-3A4000

It will crash, and same output.