[Ovirt-devel] Re: [Fedora-livecd-list] [PATCH] mkliveinitrd: wait for udev queue to clear before killing udevd

[Harald Hoyer]

Alan Pevec wrote:
> Jeremy Katz wrote:
>> On Tue, 2008-04-15 at 00:51 +0200, Alan Pevec wrote:
>>> mkliveinitrd: wait for udev queue to clear before killing udevd
>>>
>>> udevd doesn't seem to cleanup on kill, so let it clear events from 
>>> /dev/.udev/queue/
>>>
>>> Or should this be filed as udevd bug (cleanup .udev/queue/ on startup 
>>> and/or kill) ?
>>
>> We've already done one udevsettle for 30 seconds -- how does this any
>> more guarantee that things are cleared?  I suspect this should probably
> 
> We do dmsetup etc. in the meantime so more udev events appear. And if 
> all is good, it won't hang 30 sec, it continues immediately.
> 
> btw, we have unconditional 5s sleep here: 
> http://git.fedorahosted.org/git/?p=mkinitrd;a=blob;f=mkliveinitrd;h=84fcc8036d47613e33c6f3c79003900ae7b6fcae;hb=HEAD#l653 
> 
> Can we remove that?
> 
>> be handled in udev.  But what exactly are you seeing as the symptom?
> 
> start_udev after switching root times out (after default 180s) on its 
> udevsettle and after boot is finished, I still see an event 
> /devices/virtual/block/dm-1 in exported queue /dev/.udev/queue/ - I 
> assume this is b/c we killed previous instance of udevd before event 
> could be cleared.
> It's a race condition - for me it shows up when PXE booting oVirt liveCD 
> (created with livecd-iso-to-pxeboot), never when booting the same ISO 
> directly (both F9 KVM guests on F8 host). If I add eshell, which pauses 
> just before killing udevd, event is cleared.
> 
> I agree this might be seen as a workaround but killing udevd just like 
> that doesn't seem polite.
> Then again udevd should prolly clear its exported queue on startup, so 
> I'm CCing Harald to weigh in.
> 

If I understand that correctly, a udevd is running in initrd, which is killed and then normal boot with 
rc.sysinit start and start_udev is called.

Since start_udev replays all events anyway, why don't you kill udevd and remove the old queue?

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 3636 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://listman.redhat.com/archives/ovirt-devel/attachments/20080415/98035d2c/attachment.bin>