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SubjectRe: [PATCH v8 1/2] fork: extend clone3() to support setting a PID
On 11/13, Adrian Reber wrote:
>
> @@ -175,23 +187,47 @@ struct pid *alloc_pid(struct pid_namespace *ns)
>
> for (i = ns->level; i >= 0; i--) {
> int pid_min = 1;

Well, this is really minor but again, pid_min is only used in the "else"
branch below, you can move this declaration there.

> +
> + if (set_tid_size) {
> + tid = set_tid[ns->level - i];
> + if (tid < 1 || tid >= pid_max)
> + return ERR_PTR(-EINVAL);
> + /* Also fail if a PID != 1 is requested and no PID 1 exists */
> + if (tid != 1 && !tmp->child_reaper)
> + return ERR_PTR(-EINVAL);
> + if (!ns_capable(tmp->user_ns, CAP_SYS_ADMIN))
> + return ERR_PTR(-EPERM);
> + }
>
> idr_preload(GFP_KERNEL);
> spin_lock_irq(&pidmap_lock);
>
> - /*
> - * init really needs pid 1, but after reaching the maximum
> - * wrap back to RESERVED_PIDS
> - */
> - if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
> - pid_min = RESERVED_PIDS;
> -
> - /*
> - * Store a null pointer so find_pid_ns does not find
> - * a partially initialized PID (see below).
> - */
> - nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
> - pid_max, GFP_ATOMIC);
> + if (tid) {
> + nr = idr_alloc(&tmp->idr, NULL, tid,
> + tid + 1, GFP_ATOMIC);
> + /*
> + * If ENOSPC is returned it means that the PID is
> + * alreay in use. Return EEXIST in that case.
> + */
> + if (nr == -ENOSPC)
> + nr = -EEXIST;
> + set_tid_size--;
^^^^^^^^^^^^^^^
May I ask you to move this decrement into the "if (set_tid_size)" block above?

Oleg.

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