Messages in this thread | | | Date | Mon, 20 Feb 2006 18:04:48 +0100 | From | Herbert Poetzl <> | Subject | Re: [RFC][PATCH 04/20] pspace: Allow multiple instaces of the process id namespace |
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On Mon, Feb 20, 2006 at 12:27:03PM +0300, Kirill Korotaev wrote: >>>> I also don't understand why you are eager to introduce new sys >>>> calls like pkill(path_to_process), but is trying to use waitpid() >>>> for pspace die notifications? Maybe it is simply better to >>>> introduce container specific syscalls which should be clean and >>>> tidy, instead of messing things up with clone()/waitpid() and so >>>> on? The more simple code we have, the better it is for all of us.
>>> now that you mention it, maybe we should have a few >>> rounds how those 'generic' container syscalls would >>> look like?
>> I still like the following: >> >> clone(): extended with flags for asking a private copy of various >> namespaces. For the CLONE_NEWPIDSPACE flag, the pid which >> is returned to the parent process is it's handle to the >> new pidspace.
> - clone has limited number of flags. > - sooner or later you will need to add flags about what and how > you want to close (e.g. pspace with weak or strong isolation > and so on)
I still do not see a need to do that at clone() time but I assume you have your reasons for postulating this ...
>> sys_execpid(pid, argv, envp): exec a new syscall with the requested >> pid, if the pid is available. Else either return an error, >> or pick a random pid. Error makes sense to me, but that's >> probably debatable. > the problem is that in real life environments where executables can be > substitutes this is kind of a security issue. Also I really hate the > idea of using exec() for changing something.
> In OpenVZ we successfully do context changes without exec()'s.
here I agree, changes between *spaces should be independant from exex(), but IMHO there is no need to reuse existing interfaces for that, a syscall will do fine here ...
>> sys_fork_slide(pid): fork and slide into the pidspace belong to pid. >> This way we can do things like >> >> p = sys_fork_slide(2794); >> if (p == 0) { >> kill(2974); >> } else { >> waitpid(p, 0, 0); >> } >> Ok, this last one in particular needs to be improved, but these two >> syscalls and the clone flags together give us all we need. Right? > Again, you concentrate on PIDspaces forgeting about all the other > namespaces. > > I would prefer: > > - sys_ns_create() > creates namespace and makes a task to inherit this namespace. > If _needed_, it _can_ fork inside.
I don't see why not have both, the auto-created *space on clone() and the ability to create empty *spaces which can be populated and/or entered
> - sys_ns_inherit() > change active namespace.
hmm, sounds like a misnomer to me ...
> But how should we reference namespace? by globabl ID?
definitely by some system-unique identifier ...
best, Herbert
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