Messages in this thread | | | Date | Thu, 16 Aug 2007 07:13:54 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH 19/20] Changes to show virtual ids to user |
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Quoting Andrew Morton (akpm@linux-foundation.org): > On Fri, 10 Aug 2007 15:48:28 +0400 > xemul@openvz.org wrote: > > > This is the largest patch in the set. Make all (I hope) the places where > > the pid is shown to or get from user operate on the virtual pids. > > > > The idea is: > > - all in-kernel data structures must store either struct pid itself > > or the pid's global nr, obtained with pid_nr() call; > > - when seeking the task from kernel code with the stored id one > > should use find_task_by_pid() call that works with global pids; > > - when showing pid's numerical value to the user the virtual one > > should be used, but however when one shows task's pid outside this > > task's namespace the global one is to be used; > > - when getting the pid from userspace one need to consider this as > > the virtual one and use appropriate task/pid-searching functions. > > > > ... > > > > - si.si_pid = current->pid; > > + si.si_pid = task_pid_vnr(current); > > This is going to be an ongoing maintenance problem: people will sneak > new references to current->pid into the tree and nobody will notice. > > It'd be best to rename task_struct.pid to something else to catch such > problems and to force people to use the right accessors. Is that feasible?
It's certainly feasible, and something we'd previously done for instance in http://marc.info/?l=linux-kernel&m=113751118609597&w=2
> Generally this is a tactic which should be used whenever things like this > are virtualised.
Ok, it's a big invasive patchset, but there's no reason we can't do it.
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