[PATCH v2] mac80211: reject/clear user rate mask if not usable

[Johannes Berg]

On Fri, 2020-11-13 at 16:14 +0800, Wen Gong wrote:
> On 2020-11-13 15:38, Johannes Berg wrote:
> > On Fri, 2020-11-13 at 10:08 +0800, Wen Gong wrote:
> > > > Which was the intent of this change, wasn't it?
> > 
> > Indeed. Permitting this leads to warnings later.
> > 
> > > We need to set the tx rate to fixed at a single rate, e.g.,
> > > 54M/48M/36M... for a test case.
> > > I do not want a clear error message, I want to the 54M rate pass/set
> > > success to lower wlan driver.
> > > Then lower wlan driver can handle it.
> > 
> > No, that will not happen. You should configure your test AP to actually
> > support 54M.
> Yes, the AP support 54M, but it is not basic rate, so 
> ieee80211_set_bitrate_mask will reject 54M
> because fail for check (mask->control[band].legacy & basic_rates).

Ah. So this is what I said in the original commit message even:

> Technically, selecting basic rates as the criterion is a bit too
> restrictive, but calculating the usable rates over all stations
> (e.g. in AP mode) is harder, and all stations must support the
> basic rates. Similarly, in client mode, the basic rates will be
> used anyway for control frames.

I guess if we really want to redefine the user rate mask to not apply to
control frames, then we can relax this?

johannes