Re: [BK PATCH] SCSI host num allocation improvement

[Andrew Morton <akpm@osdl.org>]

Ben Collins <bcollins@debian.org> wrote:
>
> +next_host_num_try:
> +	list_for_each_entry(cdev, &class->children, node) {
> +		shost = class_to_shost(cdev);
> +		if (shost->host_no == host_num) {
> +			host_num++;
> +			goto next_host_num_try;

yitch.  I realise this is called rarely, for realtively small numbers of N
(which gets squared), but.

This allocate-me-the-lowest-available-number is a common idiom in the
kernel and we really should do it better.  Seems we need to convert the
dynamic pty allocation to do it as well - it has yet another open-coded
ad-hoc allocator.

The lib/idr.c code is a bit clumsy but it does do the job relatively
efficiently.  If it needs some helper wrappers or API simplification then
let's add those.