From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50013) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bxWH6-0004FP-Ly for qemu-devel@nongnu.org; Fri, 21 Oct 2016 05:38:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bxWH2-0008PJ-TG for qemu-devel@nongnu.org; Fri, 21 Oct 2016 05:38:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54394) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1bxWH2-0008Oz-NY for qemu-devel@nongnu.org; Fri, 21 Oct 2016 05:38:00 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ED36A3F1F0 for ; Fri, 21 Oct 2016 09:37:59 +0000 (UTC) Date: Fri, 21 Oct 2016 10:37:56 +0100 From: "Daniel P. Berrange" Message-ID: <20161021093756.GC6585@redhat.com> Reply-To: "Daniel P. Berrange" References: <20161019122158.GS11194@redhat.com> <20161019180616.GF2035@work-vm> <87oa2fwg9z.fsf@dusky.pond.sub.org> <20161020090356.GD12145@redhat.com> <20161020095835.GC2039@work-vm> <87funrti86.fsf@dusky.pond.sub.org> <20161020110832.GG12145@redhat.com> <87insnqllc.fsf@dusky.pond.sub.org> <20161020175648.GN2039@work-vm> <8760omm5pu.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8760omm5pu.fsf@dusky.pond.sub.org> Subject: Re: [Qemu-devel] chardev's and fd's in monitors List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: "Dr. David Alan Gilbert" , qemu-devel@nongnu.org On Fri, Oct 21, 2016 at 11:06:21AM +0200, Markus Armbruster wrote: > "Dr. David Alan Gilbert" writes: > > > * Markus Armbruster (armbru@redhat.com) wrote: > >> "Daniel P. Berrange" writes: > [...] > >> > Realistically all the major backend subsystems (chardev, network, block, > >> > ui and migration) need to be converted to Error ** propagation, since > >> > they all ultimately call into some common code that reports Error **. > >> > >> Infrastucture generally doesn't know how it's used, which means > >> error_report() is generally wrong there. Sufficiently simple functions > >> can keep returning -errno, null, whatever, but the interesting stuff > >> needs to use Error. > >> > Very few places will end up being able to stick with -errno, or plain > >> > error_report in the long term. > >> > >> Not sure about "very few". Less than now. We'll see. > > > > I'd also prefer we got the very-few level; Migration used to be > > characterised by getting a 'load of migration failed -22' and having > > no clue in the logs to why; I've slowly fought back to be able > > to get an error from the lowest level that caused the failure. > > I want more of that, so that when someone gets a rare failure in the field > > I can see why. > > When it's about details that are only useful for debugging, logging > might be a practical alternative. No excuse for shoddy error reporting, > of course. FWIW, I would very much like it if incoming migration were able to report the error failing to load migration stream back via the monitor, instead of spitting them to stderr - the latter makes it hard for libvirt to provide good error report to the users. On the outgoing side we've now fed the errors back via the query-migrate command - the same approach could be used on the incoming side. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|