Re: [PATCH wireless] wifi: cfg80211: remove scan request n_channels counted_by

[Kees Cook <kees@kernel.org>]

On Mon, Jul 14, 2025 at 02:21:30PM +0200, Johannes Berg wrote:
> If we really wanted to fix it, we'd need to separately track the
> number of channels allocated and the number of channels currently
> used, but given that no bugs were found despite the numerous syzbot
> reports, that'd just be a waste of time.

This mismatch between "quantity allocated" and "quantity used from the
allocation" is repeated in more places that just wifi, and I'd agree
that it has caused some confusion. The intent of __counted_by is to
track the _allocation_, so my mistake was trying to apply it in places
where the allocation size is not retained, and to shoe-horn it into the
"used" tracking member.

Any opposition to adding such a field here, maybe "avail_channels"?

-Kees

-- 
Kees Cook