ARM-software
Invalid PID when trying to kill BackgroundCommand
I have started a background task as follows:
self._process = self._target.background(f"poller -l {','.join([str(x) for x in self._files.keys()])} {' '.join(self._files.values())}", as_root=self._as_root)
When I then try to run:
self._process.cancel()
I see the following error:
Command '/home/appa/devlib-target/bin/busybox kill -15 -329893' returned non-zero exit status 1.
OUTPUT: kill: can't kill pid -329893: No such process
Checking on the device I can see that the PID does exist:
root 329893 0.0 0.0 2060 500 ? S 10:44 0:00 sh -c sh -c 'export PATH=/home/appa/devlib-target/bin:$PATH && export LC_ALL=C && poller -l 0 /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq'
root 329894 0.0 0.0 2060 472 ? S 10:44 0:00 sh -c export PATH=/home/appa/devlib-target/bin:$PATH && export LC_ALL=C && poller -l 0 /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
root 329895 0.0 0.0 936 4 ? S 10:44 0:00 poller -l 0 /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
appa 330021 0.0 0.0 8576 648 pts/0 S+ 10:45 0:00 grep --color=auto poller
~It seems the issue is the preceding -, if I run the command manually without it (/home/appa/devlib-target/bin/busybox kill -15 329893) the process is killed as expected~
It seems that when it is being wrapped by sudo, the PID returned is not the PGID.
$ ps -efj | grep 373747
UID PID PPID PGID SID C STIME TTY TIME CMD
root 373747 370822 373747 373747 0 11:43 ? 00:00:00 sudo -k -p -S -- sh -c printf '%s ' $$; exec sh -c 'sh -c '"'"'export PATH=/home/appa/devlib-target/bin:$PATH && export LC_ALL=C && poller -l 0 /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq'"'"' '
root 373748 373747 373747 373747 0 11:43 ? 00:00:00 sh -c sh -c 'export PATH=/home/appa/devlib-target/bin:$PATH && export LC_ALL=C && poller -l 0 /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq'
root 373749 373748 373747 373747 0 11:43 ? 00:00:00 sh -c export PATH=/home/appa/devlib-target/bin:$PATH && export LC_ALL=C && poller -l 0 /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
root 373750 373749 373747 373747 0 11:43 ? 00:00:00 poller -l 0 /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
appa 373769 352164 373768 352164 0 11:43 pts/0 00:00:00 grep --color=auto 373747
The PID sent to the kill command in this case was 373748, but you can see the PGID is actually 373747 which is the the outer sudo call
Interesting, thanks for reporting.
In case someone has the same idea, this PR https://github.com/ARM-software/devlib/pull/689 does not provide a workaround, since SIGTERM, SIGQUIT and SIGKILL are still handled in the same way as currently.
