[systemd-devel] Which udev action is run on boot for my device?

[Marcin Kocur]

W dniu 26.10.2020 o 11:19, Lennart Poettering pisze:
> On So, 25.10.20 18:56, Marcin Kocur (marcin2006 at gmail.com) wrote:
>
>> W dniu 25.10.2020 o 18:36, Marcin Kocur pisze:
>>> Hello,
>>>
>>> as the topic states, I want to know which action(s) from "add",
>>> "remove", "change", "move", "online", "offline", "bind", and "unbind"
>>> were triggered on my device. Is there any way to check that?
>>>
>>> At the beginning of  /usr/lib/udev/rules.d/49-sane.rules there is:
>>>
>>> ACTION!="add", GOTO="libsane_rules_end"
>>>
>>> Udevadm info doesn't show libsane_matched property for my scanner.
>>>
>>> If I trigger the device manually with action "change", the variable is
>>> still not there, as per the rule.
>>>
>>> But if I trigger it with "add", the variable is there and also uaccess
>>> rule gets executed.
>>>
>>> So the ultimate quesiton is: what kind of trigger was executed on my
>>> device on boot time?
>>>
>> Okay, it seems that "bind" is the action executed. I just edit the ACTION
>> rule and restarted my PC until I found it.
> The introduction of "bind" and "unbind" is some major kernel API
> fuck-up btw. It's the main reason why packages should check for
> !="remove" rather than =="add|change" or so. udev rules written for
> old kernels simple didn't have to take "bind" and "unbind" into
> account. The fact that kernel just added that willy-nilly breaks rules
> all over the place. (that said, sane's apparent use of =="add" was
> always broken, i.e. the omission of "change", so even without the
> kernel bind/unbind mess the sane rules already were broken)
>
> Also see the NEWS note on the upcoming systemd version 247:
>
> https://github.com/systemd/systemd/blob/master/NEWS#L5
>
>> Is this intended? Should I report bug to systemd or sane? The scanner is
>> connected to my PC all the time.
> sane.
>
> Ask them to run their rules on ACTION!="remove", i.e. on all actions
> but "remove". And that includes add, bind, change, unbding and
> everything else that might be added one day.
>
> Lennart
>
> --
> Lennart Poettering, Berlin

Thanks Lennart and Pekka,

I drawed SANE's maintainers attention to this:

https://gitlab.com/sane-project/backends/-/issues/371

https://gitlab.com/sane-project/backends/-/merge_requests/541

-- 
Pozdrawiam / Greetings
Marcin Kocur █