rate control vs. bands

[Johannes Berg <johannes@sipsolutions.net>]

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Hi,

During my rate control work I noticed that the band handling there is
somewhat awkward, and I wanted to collect opinions.

Currently, much of the code assumes that neither we nor station in our
bSS change bands; the PID algorithm even says:

        /* We can safely assume that sband won't change unless we get
         * reinitialized. */

which doesn't really seem true.

For the rate control algorithms, I was just thinking about removing the
rate_init() callback because this can just as well be done when
allocating the station. However, currently we don't pass the band to the
alloc_sta function, so that isn't possible right now.


It seems like it's well possible that say in an IBSS we have two
stations both dual-band capable and one manually switches them to a
different channel on a different band. This seems to totally throw off
everything we do, it'll be beaconing with an entirely bogus supported
rate set etc. However, it seems that it might also crash the rate
control algorithms.

Any ideas? Should we remove the rate_init function entirely and require
the RC algorithm to initialise for bands the hardware supports? (Those
can be checked via the 'hw' pointer argument we give to the alloc()
callback on the RC API.)

I'm currently leaning towards that, but what about HT stuff? Will that
change between bands? Is there anything band-specific? Why doesn't
anybody but me think about these corner cases?

johannes

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