[systemd-devel] udev "uaccess" tag does not support "hotplug" for some devices

[Tom Yan]

Hi all!

So I added the following rules:
[tom at localhost ~]$ grep . /etc/udev/rules.d/*
/etc/udev/rules.d/uas.rules:DRIVERS=="uas", TAG+="uaccess"
/etc/udev/rules.d/usb-storage.rules:DRIVERS=="usb-storage", TAG+="uaccess"

The rules basically works, but it doesn't support "hotplug", that is,
I have to re-login for newly plugged devices to get the ACLs, and I
have to do that as well if I replugged the device after I logged in.

However, it doesn't seem to be a universal limitation, because it does
support "hotplug" for my SATA optical drive. I enabled hotplug of that
SATA port in BIOS, unplugged the SATA cable, made sure "cdrom"
(symlink) and "sr0" are no longer in /dev, then plugged it in again,
the ACLs remains. I also tried to boot without the optical drive
connected, and plugged in after login, it also works fine.

So could it be a bug of udev or logind, or something wrong with
certain kernel drivers?