From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nadia Derbey Subject: Re: [RFC][PATCH 0/4] Object creation with a specified id Date: Fri, 14 Mar 2008 17:11:34 +0100 Message-ID: <47DAA3B6.5080908@bull.net> References: <20080310135054.312992000@bull.net> <47D9B5B7.6060803@cs.columbia.edu> <47DA195B.8070704@bull.net> <47DA9EB5.8040704@cs.columbia.edu> <47DAA041.9090009@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <47DAA041.9090009-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Pavel Emelyanov Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: containers.vger.kernel.org Pavel Emelyanov wrote: > Oren Laadan wrote: > >>Nadia Derbey wrote: >> >>>Oren Laadan wrote: >>> >>>>Nadia.Derbey-6ktuUTfB/bM@public.gmane.org wrote: >>>> >>>> >>>>>A couple of weeks ago, a discussion has started after Pierre's >>>>>proposal for >>>>>a new syscall to change an ipc id (see thread >>>>>http://lkml.org/lkml/2008/1/29/209). >>>>> >>>>> >>>>>Oren's suggestion was to force an object's id during its creation, >>>>>rather >>>>>than 1. create it, 2. change its id. >>>>> >>>>>So here is an implementation of what Oren has suggested. >>>>> >>>>>2 new files are defined under /proc/self: >>>>> . next_ipcid --> next id to use for ipc object creation >>>>> . next_pids --> next upid nr(s) to use for next task to be forked >>>>> (see patch #2 for more details). >>>> >>>>Generally looks good. One meta-comment, though: >>>> >>>>I wonder why you use separate files for separate resources, >>> >>>That would be needed in a situation wheere we don't care about next, >>>say, ipc id to be created but we need a predefined pid. But I must admit >>>I don't see any pratical application to it. >> >>exactly; why set the next-ipc value so far in advance ? I think it's >>better (and less confusing) if we require that setting the next-id value >>be done right before the respective syscall. > > > And race with some other syscall caller? This will only work if the next-ipc-id > and the next-pid are on a task_struct. Are they (at least supposed to be such)? > > Yes they are. Regards, Nadia