Message-ID: <07e019232f1720ce70d3353ce73cd32a23e5ed2f.camel@sipsolutions.net>
Subject: Re: question: crda timeout in cfg80211
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>,
        "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Cc:     Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Date:   Mon, 08 Apr 2019 21:06:16 +0200
In-Reply-To: <20190326124209.j6tdk5cz47kc6mdj@bars> (sfid-20190326_134333_009337_40AB75D9)
References: <20190326124209.j6tdk5cz47kc6mdj@bars>
         (sfid-20190326_134333_009337_40AB75D9)
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On Tue, 2019-03-26 at 12:42 +0000, Sergey Matyukevich wrote:
> Hi all,
> 
> Linux cfg80211 regulatory subsystem uses CRDA timeout to ensure completion
> of regulatory updates, performed by user-space software. See call_crda
> functon in net/wireless/reg.c:
> 
> static int call_crda(const char *alpha2)
> {
> 	...
> 
> 	queue_delayed_work(system_power_efficient_wq,
> 			&crda_timeout, msecs_to_jiffies(3142));
> 	return 0;
> }
> 
> So regulatory update/reset operations shall be completed in 3142 msec.
> And that includes processing of regulatory notifiers for all the
> wireless cards in the system.
> 
> It is not quite clear where this specific timeout value came from.
> Original commit (a90c7a313a1c5b) doesn't go into details about it.
> 
> Any ideas where it could come from ?

No particular reason. It's just ~pi seconds, and IIRC Luis thought that
was funny :-)

Are you seeing any issues with that?

johannes