Re: [PATCH 3/6][v5] Define siginfo_from_ancestor_ns()

Oleg Nesterov
2009-01-05T12:45:08Z

On 12/27, Sukadev Bhattiprolu wrote:
>
> +static inline int siginfo_from_ancestor_ns(struct task_struct *t,
> + siginfo_t *info)
> +{
> + struct pid_namespace *ns;
> +
> + /*
> + * Ensure signal is from user-space before checking pid namespace.
> + * (We maybe called from interrupt context and dereferencing
> + * pid namespace would be safe).
> + */
> + if (siginfo_from_user(info)) {
> + /*
> + * If we do not have a pid in the receiver's namespace,
> + * we must be from an ancestor namespace.
> + *
> + * Note:
> + * If receiver is exiting, ns == NULL,

Confused. I thought we alread have the patch which ensures
task_active_pid_ns() is never NULL?

If not, we can get ns from task_pid(t). See also below.

> signal will be
> + * queued but eventually ignored anyway (wants_signal()
> + * is FALSE).

This is only true for thread-specific signals, please remove
this comment,

> + ns = task_active_pid_ns(t);
> + if (!ns || task_pid_nr_ns(current, ns) <= 0)
> + return 1;

See above. In any case, we shouldn't return 1 if ns == NULL.
But afaics we always can know its namespace.

Oleg.