It's best practice to run as little code as possible as root (especially
when listening to network ports). When not itself running as root
already, remote-fw-service.py has always tried to invoke cavstool.py
with "sudo". Unfortunately this looks like it never worked; at least not
on Ubuntu 22 where this commit was tested. Moreover it did not fail
immediately but mysteriously timed out without any useful error message.
- The first, most obvious bug was that "sudo" does not propagate
SIGKILL (and a few other signals), see "man sudo". Compare:
```
$ sudo sleep 30 &
$ kill $! # sudo propagates the TERM signal and sleep is terminated
$ sudo sleep 30 & sudoPID=$!
$ kill -KILL $sudoPID
$ ps xfao pid,ppid,pgid,sid,comm | grep -C 5 -e PID -e sleep -e sudo
```
Fix this by invoking proc.terminate() first before proc.kill().
proc.terminate() is more "polite" with cavstool even when not using
sudo.
- Second issue: when signals are sent to sudo, strace shows that its
signal handler invokes `getpgid()` and then ignores signals coming from
its own process group. `man sudo` states: "sudo will not relay signals
that were sent by the command it is running...", which seems related.
`start_new_session=True` option moves sudo to a different PGID which
stops sudo from ignoring signals from its remote-fw-service.py parent.
Signed-off-by: Marc Herbert <marc.herbert@intel.com>
67f7b43136