Bug#765577: netboot install writes duplicates to 70-persistent-net.rules

[Michael Biebl]

Control: tags -1 confirmed

Am 18.03.2015 um 19:50 schrieb Michael Biebl:
> Am 18.03.2015 um 18:52 schrieb Michael Biebl:
>> Am 18.03.2015 um 18:15 schrieb Faidon Liambotis:
>>> Another less arbitrary/racy workaround I suggesed was a grep near the
>>> top of write_net_rules' write_rule() function.  Since write_rule()
>>> operates under a lock, this would completely eliminate any kind of race
>>> here. I pitched this to Marco but he wasn't thrilled with the idea -- he
>>> said he'd prefer finding the root cause. I've done the change and tested
>>> it anyway, though, and it successfully aleviates this issue:
>>
>> I'm with Marco here. Before adding any workarounds, we need to
>> understand what the underlying problem is. Otherwise we are adding cruft
>> which nobody understands anymore a few years from now.
>>
>> Since I can't reproduce the issue and already have trouble keeping up
>> with other bug reports, further investigation needs to be done by
>> someone else.
> 
> Btw, thanks for looking into this.
> Would be awesome if you can dig further and get to the bottom of this.

Looks like a found a simple reproducer (this is on my work laptop) done
during normal runtime of the system:

$ rm /etc/udev/rules.d/70-persistent-net.rules
$ while  true ; do echo add > /sys/class/net/eth0/uevent ; done

I let this run for one or two seconds and had over 100 entries in
70-persistent-net.rules.
udevd went totally nuts and consumed almost 100% CPU, but a simple
systemctl restart systemd-udevd.service fixed that.


So, while I don't have a solution yet, at least I have now a simple way
to reproduce it reliably. Therefor marking the bug accordingly.

-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?

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