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SubjectRe: [RFC][v6][PATCH 0/9] clone_with_pids() syscall
On Friday 11 September 2009, Peter Zijlstra wrote:
> 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.

I would leave out the size argument. We can put a few reserved fields
and flag bits in there for possible extensions, but if we ever run out
of these, just define a new syscall.

Also, if you're passing a struct, why not put nr_pids in there, and
replace clone_pid_struct with a simple array? That would give us

struct clone_struct {
u64 flags;
u64 child_stack;
u32 child_tid;
u32 parent_tid;
u32 nr_pids;
u32 reserved1;
u64 reserved2;

int clone2(struct clone_struct *cs, pid_t *pids);

Arnd <><

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