Fix process_spawned_and_wait_in_different_runtime on linux with pidfd

Signed-off-by: Jiahao XU <[email protected]>

tokio/src/io/poll_evented.rs

@@ -144,6 +144,17 @@ impl<E: Source> PollEvented<E> {
  .map_err(io::Error::from)
  .map_ok(|_| ())
  }
+
+ /// Re-register under new runtime with `interest`.
+ #[cfg(all(feature = "process", target_os = "linux"))]
+ pub(crate) fn reregister(&mut self, interest: Interest) -> io::Result<()> {
+ let io = self.io.as_mut().unwrap(); // As io shouldn't ever be None, just unwrap here.
+ let _ = self.registration.deregister(io);
+ self.registration =
+ Registration::new_with_interest_and_handle(io, interest, scheduler::Handle::current())?;
+
+ Ok(())
+ }
 }
 
 feature! {

tokio/src/process/unix/pidfd_reaper.rs

@@ -4,6 +4,7 @@ use crate::{
  imp::{orphan::Wait, OrphanQueue},
  kill::Kill,
  },
+ util::error::RUNTIME_SHUTTING_DOWN_ERROR,
 };
 
 use libc::{syscall, SYS_pidfd_open, __errno_location, ENOSYS, PIDFD_NONBLOCK};
@@ -93,6 +94,17 @@ where
  pidfd: PollEvented<Pidfd>,
 }
 
+#[allow(deprecated)]
+fn is_rt_shutdown_err(err: &io::Error) -> bool {
+ if let Some(inner) = err.get_ref() {
+ // Using `Error::description()` is more efficient than `format!("{inner}")`,
+ // so we use it here even if it is deprecated.
+ inner.source().is_none() && inner.description() == RUNTIME_SHUTTING_DOWN_ERROR
+ } else {
+ false
+ }
+}
+
 impl<W> Future for PidfdReaperInner<W>
 where
  W: Wait + Unpin,
@@ -102,7 +114,13 @@ where
  fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
  let this = Pin::into_inner(self);
 
- ready!(this.pidfd.poll_read_ready(cx))?;
+ match ready!(this.pidfd.poll_read_ready(cx)) {
+ Err(err) if err.kind() == io::ErrorKind::Other && is_rt_shutdown_err(&err) => {
+ this.pidfd.reregister(Interest::READABLE)?;
+ ready!(this.pidfd.poll_read_ready(cx))?
+ }
+ res => res?,
+ }
  Poll::Ready(Ok(this
  .inner
  .try_wait()?