Re: changing dev->needed_headroom/needed_tailroom?

Ben Hutchings
2013-08-02T08:55:58Z

On Fri, 2013-07-26 at 16:50 +0200, Johannes Berg wrote:
> Does it seem reasonable to change dev->needed_headroom and
> dev->needed_tailroom on the fly?
>
> We currently set needed_headroom to the max of what we need, but we
> could do better like making it depend on the interface type (e.g. only
> asking for mesh space on mesh interfaces). This would be done only when
> the interface isn't connected, I can't promise it would be down but the
> carrier would be off.
[...]

I don't think this is safe when the interface is running (even if
carrier is off). Some functions may read dev->needed_headroom twice and
rely on getting the same value each time.

Also, stacked devices would need to adjust their own needed_headroom
accordingly.

Ben.

--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.