Re: port-xen/50659: Xen4.5 crash with vnds

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

The following reply was made to PR kern/50659; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: Christoph Badura <bad%bsd.de@localhost>
Cc: gnats-bugs%netbsd.org@localhost, kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
        netbsd-bugs%netbsd.org@localhost, sebastian%xenoserver.net@localhost
Subject: Re: port-xen/50659: Xen4.5 crash with vnds
Date: Thu, 24 Mar 2016 21:38:06 +0100

 On Thu, Mar 24, 2016 at 06:53:20PM +0100, Christoph Badura wrote:
 > On Wed, Mar 23, 2016 at 09:23:22AM +0100, Manuel Bouyer wrote:
 > > I think it is Xen's problem.
 > > I noticed that xen 4.5 starts domUs concurently (/etc/rc.d/xendomains start)
 > > which prevented be from upgrading to 4.5 because of concurency problems
 > > in my network scripts (local change).
 > > 
 > > Now if it runs scripts for each block device (or, I guess, each
 > > network device) in parallel, then we have a problem.
 > 
 > xl does indeed run the device hotplug scripts in parallel.  c.f.
 > libxl/libxl_device.c:device_hotplug().
 > 
 > If you looks at the linux hotplug scripts, they do their own serialization
 > as appropriate.  "grep -r _lock hotplug/Linux".
 
 I tried to do something with shlock(1) but it doens't work, it's too
 slow and xl times out. 
 Maybe flock would work but older NetBSD don't have it ...
 
 -- 
 Manuel Bouyer <bouyer%antioche.eu.org@localhost>
      NetBSD: 26 ans d'experience feront toujours la difference
 --