[Bug 1819108] Re: qemu-bridge-helper failure but qemu not exit

[Thomas Huth <1819108@bugs.launchpad.net>]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/166


** Changed in: qemu
       Status: New => Expired

** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #166
   https://gitlab.com/qemu-project/qemu/-/issues/166

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https://bugs.launchpad.net/bugs/1819108

Title:
  qemu-bridge-helper failure but qemu not exit

Status in QEMU:
  Expired

Bug description:
  When qemu-bridge-helper run failed, its parent process qemu is still alive.
  This is my command line:

  qemu-system-x86_64 -curses -enable-kvm -cpu host -smp 4 -m 4096 \
    -vnc :1 \
    -kernel /data/xugang_vms/boot/vmlinuz \
    -initrd /data/xugang_vms/boot/initram \
    -append 'module_blacklist=drm,evbug net.ifnames=0 biosdevname=0 ROOTDEV=rootfs' \
    -drive file=/data/xugang_vms/instances/vn7/rootfs.img,format=qcow2,if=virtio \
    -monitor unix:/data/xugang_vms/var/monitor/vn7.sock,server,nowait \
    -netdev bridge,br=vmbr99,helper="/root/bridgehelper --ns=kvm_1 ",id=n1 -device virtio-net,netdev=n1,mac=92:99:98:76:01:07

  "/root/bridgehelper" is self defined helper binary by me. But after
  bridge-helper exited with failure(not send fd to qemu process yet),
  the linux vm's console will be messed up. I checked the qemu source
  code(at net/tap.c) and found following snip:

  ===>
  do {
              fd = recv_fd(sv[0]);
          } while (fd == -1 && errno == EINTR);
          saved_errno = errno;

          close(sv[0]);

          while (waitpid(pid, &status, 0) != pid) {
              /* loop */
          }
  <=========

  why recv_fd will infinitely wait for recv? Maybe it shall waitpid and
  then recv_fd ?

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