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Revision 885660bd

ID885660bd48efbe3742892e06de7a8898703e0bdc

Added by Michael Roth over 12 years ago

network scripts: don't block SIGCHLD before forking

This patch fixes a bug where child processes of launch_script() can
misbehave due to SIGCHLD being blocked. In the case of `sudo`, this
causes a permanent hang.

Previously a SIGCHLD handler was added to reap fork_exec()'d zombie
processes by calling waitpid(-1, ...). This required other
fork()/waitpid() callers to temporarilly block SIGCHILD to avoid
having the final wait status being intercepted by the SIGCHLD
handler:

7c3370d4fe3fa6cda8655f109e4659afc8ca4269

Since then, the qemu_add_child_watch() interface was added to allow
registration of such processes and reap only from that specific set
of PIDs:

4d54ec7898bd951007cb6122d5315584bd41d0c4

As a result, we can now avoid blocking SIGCHLD in launch_script(), so
drop that behavior.

Reviewed-by: Jan Kiszka <>
Reviewed-by: Paolo Bonzini <>
Signed-off-by: Michael Roth <>
Signed-off-by: Anthony Liguori <>

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