Workers do not timeout when udev_log="err"

[ardrabczyk]

Steps to reproduce:

/etc/udev/rules.d/50-test.rules:

ACTION=="add",KERNEL=="sd?[0-9]",RUN+="/home/ja/udev/udev-script.sh"

/home/ja/udev/udev-script.sh:

#!/usr/bin/env sh

echo $$ > /tmp/UDEV
/home/ja/udev/sleep.sh &

/home/ja/udev/sleep.sh:

#!/usr/bin/env sh
sleep 9999

/etc/udev/udev.conf:

# see udev.conf(5) for details

udev_log="err"

Start udevd in daemon mode:

$ /sbin/udevd --daemon

What happens:

Insert an USB stick, /tmp/UDEV gets created but udev-script.sh is
quickly reaped:

$ ps   $(cat /tmp/UDEV)
PID TTY      STAT   TIME COMMAND

even though sleep.sh is still running:

$ ps aux | grep '[s]leep'
root     21787  0.0  0.0   4080  3072 ?        S    01:41   0:00 sh /home/ja/udev/sleep.sh
root     21788  0.0  0.0   2452   684 ?        S    01:41   0:00 sleep 9999

What should happen:

When udev_log is set to debug, info or is not set udev-script.sh
becomes zombie process:

$ ps $(cat /tmp/UDEV)
PID TTY      STAT   TIME COMMAND
23462 ?        Z      0:00 [sh] <defunct>

and after some time you can see this in /var/log/syslog:

May  3 01:49:36 darkstar kernel: [324524.629614] udevd[23327]: worker [23427] /devices/pci0000:00/0000:00:14.0/usb2/2-6/2-6:1.0/host7/target7:0:0/7:0:0:0/block/sdc/sdc1 is taking a long time
May  3 01:51:36 darkstar kernel: [324644.684026] udevd[23327]: worker [23427] /devices/pci0000:00/0000:00:14.0/usb2/2-6/2-6:1.0/host7/target7:0:0/7:0:0:0/block/sdc/sdc1 timeout; kill it
May  3 01:51:36 darkstar kernel: [324644.684047] udevd[23327]: seq 38047 '/devices/pci0000:00/0000:00:14.0/usb2/2-6/2-6:1.0/host7/target7:0:0/7:0:0:0/block/sdc/sdc1' killed
May  3 01:51:36 darkstar kernel: [324644.684449] udevd[23327]: worker [23427] terminated by signal 9 (Killed)
May  3 01:51:36 darkstar kernel: [324644.684452] udevd[23327]: worker [23427] failed while handling '/devices/pci0000:00/0000:00:14.0/usb2/2-6/2-6:1.0/host7/target7:0:0/7:0:0:0/block/sdc/sdc1'

In this case udev waits not only for death of its own children but
also children of children and so on before reaping udev-script.sh by
passing a file descriptor that will be inherited by all descendant
processes. Why doesn't it work like that with udev_log="err"?

[ardrabczyk]

It looks like a feature - pipes from child to parent are created in udev_event_spawn() only if udev_log is >= LOG_INFO.