Cedric Le Goater wrote:
> Pavel Emelyanov wrote:
>> Dave Hansen wrote:
>>> On Mon, 2008-01-14 at 16:36 -0500, Oren Laadan wrote:
>>>> I second the concern of running out of 64 bits of flags. In fact, the
>>>> problem with the flags is likely to be valid outside our context, and
>>>> general to the linux kernel soon. Should we not discuss it there
>>>> too ?
>>> It would be pretty easy to make a new one expandable:
>>>
>>> sys_newclone(int len, unsigned long *flags_array)
>>>
>>> Then you could give it a virtually unlimited number of "unsigned long"s
>>> pointed to by "flags_array".
>>>
>>> Plus, the old clone just becomes:
>>>
>>> sys_oldclone(unsigned long flags)
>>> {
>>> do_newclone(1, &flags);
>>> }
>>>
>>> We could validate the flags array address in sys_newclone(), then call
>>> do_newclone().
>> Hmm. I have an idea how to make this w/o a new system call. This might
>> look wierd, but. Why not stopple the last bit with a CLONE_NEWCLONE and
>> consider the parent_tidptr/child_tidptr in this case as the pointer to
>> an array of extra arguments/flargs?
>
> It's a bit hacky but it looks like a good idea to me !
>
> Shall we use parent_tidptr or child_tidptr to pass a extended array of
> flags only ? if we could pass the pid of the task to be cloned, it would
> be useful for c/r.
Yup. I think we can declare a
struct new_clone_arg {
unsigned int size;
};
and consider the xx_tidptr to be a pointer on it. After this we
may sen patches that add fields to this structure.
E.g. first
struct new_clone_arg {
unsigned int size;
+ unsigned long new_flags;
};
to add flags for cloning new namespaces. Later
struct new_clone_arg {
unsigned int size;
unsigned long new_flags;
+ int desired_pid;
};
and each code that needs to access the extra argument would need
to check for new_clone_arg->size to be not less than the offset
of the field he need an access to. E.g. like this:
#define clone_arg_has(arg, member) ({ \
struct new_clone_arg *__carg = arg; \
(__carg->size >= offsetof(struct new_clone_arg, member) + \
sizeof(__carg->member)) })
...
if (!clone_arg_has(arg, desired_pid))
return -EINVAL;
This would keep the API always compatible.
> C.
>
Thanks,
Pavel
_______________________________________________
Containers mailing list
[EMAIL PROTECTED]
https://lists.linux-foundation.org/mailman/listinfo/containers
_______________________________________________
Devel mailing list
Devel@openvz.org
https://openvz.org/mailman/listinfo/devel
