[PATCH 2/2] ath10k: support MAC address randomization in scan

Brian Norris briannorris at chromium.org
Tue Apr 17 15:26:06 PDT 2018

On Tue, Apr 17, 2018 at 2:49 PM, Arend van Spriel
<arend.vanspriel at broadcom.com> wrote:
> On 4/17/2018 6:07 PM, Brian Norris wrote:
>> On Tue, Apr 17, 2018 at 10:22:13AM +0200, Arend van Spriel wrote:
>>> I believe checking command support is not really recommended. Instead, you
>>> better check NL80211_ATTR_SCHED_SCAN_MAX_REQS being non-zero (since kernel
>>> 4.12 that is).
>> Why not? Command support checking is what wpa_supplicant is doing.
> That's not really a good argument. A couple (or more) years ago wpa_supplicant was not doing nl80211 but wext and some other using driver private ioctls, but that did not make it the best approach.

I see what you're saying (though your comparison doesn't seem that
fair either; private ioctls are nothing like a well-defined nl80211
support list), and I'm totally good on looking at the new flag
eventually. But you still haven't answered my question ("why not?").
Is there a problem with the "supported commands" list?

> The START_SCHED_SCAN command is indeed still provided to user-space:

And as I see it, it probably needs to be for essentially forever. Or
at least a significant amount of time after wpa_supplicant stops
relying on it. (Hint: it's still using it today, with no reference to
NL80211_ATTR_SCHED_SCAN_MAX_REQS.) There's a reason the kernel has ABI
guarantees. I suspect you only get a chance to rewrite the world (WEXT
-> nl80211) a few times in the life of kernel ABIs.


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