Re: [RFC][v6][PATCH 0/9] clone_with_pids() syscall

[Peter Zijlstra <peterz@infradead.org>]

On Wed, 2009-09-09 at 23:06 -0700, Sukadev Bhattiprolu wrote:

> Based on these requirements and constraints, we have been exploring a couple
> of system call interfaces and appreciate any iput.  

Why not have something like:

struct clone_struct {
	u32 size;
	u32 __reserved;
	u64 flags;
	u64 child_stack;
	u32 child_tid;
	u32 parent_tid;
};

struct clone_pid_struct {
	u32 nr;
	pid_t pids[];
};

int clone2(struct clone_struct *cs, struct clone_pid_struct *cps);

If you then get passed a longer clone_struct than you know about, all is
well IFF the tail is 0, otherwise fail with -E2BIG.

If you get passed a short clone_struct, zero out the tail.