[systemd-devel] Unable to override systemd-udevd.service

[Andrey Borzenkov]

В Thu, 24 Apr 2014 12:07:37 +0200
David Gstir <david at sigma-star.at> пишет:

> [Resend to mailing list, because my client somehow swallowed half the Cc fields - sorry about that.]
> 
> Hi!
> 
> I encountered the same issue, running version 195-13.45.1 from opensuse in a container:
> 
> On 23.04.2014, at 19:26, Andrey Borzenkov (by way of Andrey Borzenkov <arvidjaar at gmail.com>) <arvidjaar at gmail.com> wrote:
> 
> > В Wed, 23 Apr 2014 06:43:04 +0200
> > Lennart Poettering <lennart at poettering.net> пишет:
> > 
> >> On Sun, 30.03.14 19:23, Andrey Borzenkov (arvidjaar at gmail.com) wrote:
> >> 
> >>> linux-qbc6:~ # systemctl show systemd-udevd.service -p FragmentPath
> >>> FragmentPath=/usr/lib/systemd/system/systemd-udevd.service
> >>> linux-qbc6:~ # cp /usr/lib/systemd/system/systemd-udevd.service /etc/systemd/system
> >>> linux-qbc6:~ # systemctl daemon-reload 
> >>> linux-qbc6:~ # cp /usr/lib/systemd/system/systemd-udevd.service /etc/systemd/system
> >>> linux-qbc6:~ # systemctl show systemd-udevd.service -p FragmentPath
> >>> FragmentPath=/usr/lib/systemd/system/systemd-udevd.service
> >>> linux-qbc6:~ # exit
> >>> 
> >>>> From non-exhaustive testing it appears to be the only unit showing this
> >>> property. Enabling systemd debug does not add any useful information
> >>> (no output about unit discovery). Any way to debug it?
> >>> 
> >>> The version is systemd-208-19.1.x86_64 from openSUSE.
> >> 
> >> Hmm, that's weird. Is /etc on some weird mount point or so?
> >> 
> > 
> > Not really. Just plain disk in QEMU VM.
> > 
> > 17 21 0:5 / /dev rw,relatime shared:2 - devtmpfs devtmpfs rw,size=380164k,nr_inodes=95041,mode=755
> > 18 17 0:15 / /dev/shm rw,relatime shared:3 - tmpfs tmpfs rw
> > 19 21 0:16 / /run rw,nosuid,nodev,relatime shared:6 - tmpfs tmpfs rw,mode=755
> > 20 17 0:11 / /dev/pts rw,relatime shared:4 - devpts devpts rw,gid=5,mode=620,ptmxmode=000
> > 21 1 8:2 / / rw,relatime shared:1 - ext4 /dev/sda2 rw,data=ordered
> > ... etc
> > 
> 
> Similar situation here.
> 
> 
> >> It might be interesting to run "strace -o log -e open -p 1" and then trigger a
> >> reload, and then look at the generate log file "log". It should show you
> >> where systemd is looking for the udev service file, and might contain a
> >> hint, why it skips the file in /etc?
> >> 
> > 
> > Actually, it does not :)
> > 
> > 1     open("/usr/lib/systemd/system/systemd-udevd.service", O_RDONLY|O_NOCTTY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC) = 17
> > 1     open("/usr/lib/systemd/system/systemd-udevd-kernel.socket", O_RDONLY|O_NOCTTY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC) = 17
> > 1     open("/usr/lib/systemd/system/systemd-udevd-control.socket", O_RDONLY|O_NOCTTY|O_LARGEFILE|O_NOFOLLOW|O_CLOEXEC) = 17
> > 1     open("/etc/systemd/system/systemd-udevd.service", O_RDONLY|O_NOCTTY|O_LARGEFILE|O_CLOEXEC) = 18
> > 1     openat(AT_FDCWD, "/etc/systemd/system/systemd-udevd.service.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> > 1     openat(AT_FDCWD, "/run/systemd/system/systemd-udevd.service.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> > 1     openat(AT_FDCWD, "/run/systemd/generator/systemd-udevd.service.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> > 1     openat(AT_FDCWD, "/usr/local/lib/systemd/system/systemd-udevd.service.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> > 1     openat(AT_FDCWD, "/usr/lib/systemd/system/systemd-udevd.service.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> > 1     openat(AT_FDCWD, "/lib/systemd/system/systemd-udevd.service.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
> > 
> 
> Systemd does not even try to open the override in /etc here either. However, I noticed an error with /usr/lib/systemd/system/udev.service: 
> <snip>
> open("/usr/lib/systemd/system/udev.service", O_RDONLY|O_NOCTTY|O_NOFOLLOW|O_CLOEXEC) = -1 ELOOP (Too many levels of symbolic links)
> open("/usr/lib/systemd/system/systemd-udevd.service", O_RDONLY|O_NOCTTY|O_NOFOLLOW|O_CLOEXEC) = 15
> <snip>
> 
> Interestingly, removing /usr/lib/systemd/system/udev.service (which is just a symlink to systemd-udevd.service) makes the override work:
> <snip>
> open("/etc/systemd/system/systemd-udevd.service", O_RDONLY|O_NOCTTY|O_NOFOLLOW|O_CLOEXEC) = 15
> <snip>
> 
> Could it be that this symlink somehow causes systemd to ignore the override?
> Andrey, do you have similar behavior with /usr/lib/systemd/system/udev.service?
> 

Yes, I have the same link and the same ELOOP behavior ... and yes,
removing link makes it work.

Looks like systemd bug at the end ...