Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API

Gargi Sharma
2017-10-01T10:36:31Z

On Sun, Oct 1, 2017 at 2:45 PM, Christoph Hellwig <hch@infradead.org> wrote:
>> - task_active_pid_ns(current)->last_pid);
>> + task_active_pid_ns(current)->idr.idr_next-1);
>
> I think we want a well documented helper for this pattern instead
> of poking into the internals.
idr_get_cursor() get can be used instead of idr.idr_next, so that we do not
expose the internals.
>
> Also is last - 1 always the correct answer? Even with idr_alloc_cyclic
> we could wrap around, couldn't we?
-1 will be incorrect when the pids wrap around. Should we go back to
setting up last_pid as it was done before? Or should we use idr_get_cursor
and determine if pid was rolled over and then perform necessary action?

Thanks!
Gargi