Message-ID: <19f9db0cb17f886b712f47a461b876946cd4f417.camel@sipsolutions.net>
Subject: Re: question: crda timeout in cfg80211
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Cc:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
        Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>,
        Luis Chamberlain <mcgrof@do-not-panic.com>
Date:   Tue, 23 Apr 2019 14:31:36 +0200
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Hi Sergey,

On Thu, 2019-04-11 at 12:40 +0000, Sergey Matyukevich wrote:
> Calling regulatory notifiers in parallel sounds like a good idea.
> But I haven't yet looked into the details as well. Before fixing
> the timeout issue, I was trying to figure out why that regulatory
> reset was needed at all.

:-)

> Here is a simple usecase: Linux distro sets regulatory region to US,
> STA is connected to AP. Any STA disconnect (including an attempt to
> reconnect to another AP) leads to regulatory reset cycle: US -> 00 -> US.
> This reset cycle is not supposed to be done for the wireless cards that
> specify REGULATORY_COUNTRY_IE_IGNORE flag. However regulatory reset will
> be applied anyway if at least one card in the system does not specify
> that flag.
> 
> Hence two questions:
> Do we really need this kind of reset when we remain
> in the same regulatory domain ? 

Probably doesn't make sense. If I were to guess I'd say that was a
simplification, since in many cases we'd actually be doing something
like (intersected) -> 00 -> US?

Actually, in your example, we're probably doing "US->00" and "00->US"
separately since we don't really know that we're going to connect again
to a similar AP, right?

Adding Luis, just in case he remembers anything about this ...

> Does it make sense to track when restore_regulatory_settings performs
> reset, and to skip reset for the cards that specify
> REGULATORY_COUNTRY_IE_IGNORE ?

I guess that'd make some sense anyway?

I do think ultimately we need some kind of reset every once a while when
we're disconnected, otherwise we'll just carry around intersections and
other baggage forever.

johannes