From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ECB45C43334 for ; Mon, 20 Jun 2022 00:13:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236352AbiFTANp (ORCPT ); Sun, 19 Jun 2022 20:13:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237072AbiFTANZ (ORCPT ); Sun, 19 Jun 2022 20:13:25 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E3E5FE08 for ; Sun, 19 Jun 2022 17:13:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655684003; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=lzXXCZk15gEIaB/UXj3e2E+9WNxr1m0xkz5FrfPwLsY=; b=T8xDqm5FqIBM8HS/ix+ZuLF7wCLe+O237x2cqUy0IZAHLNh5y0XBICsK7Rkslk3f8GGCEj aCJWvRPqW2q9V/OYMe2hm90Ea+Fm0GXi4fNCRGtsvQNamJQqWnWwJnJB1md6DhTEDmbxNL bImAJr+rvbCsV5R50YHs+QHdYymDXlE= Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-210-ABB3C0itO4q51H_KxwOnkg-1; Sun, 19 Jun 2022 20:13:21 -0400 X-MC-Unique: ABB3C0itO4q51H_KxwOnkg-1 Received: by mail-qv1-f72.google.com with SMTP id t5-20020a0cb385000000b0046e63b0cef8so10301935qve.23 for ; Sun, 19 Jun 2022 17:13:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=lzXXCZk15gEIaB/UXj3e2E+9WNxr1m0xkz5FrfPwLsY=; b=H2eE/U0phfXZGQV9jUBtX/pL84gLzS0nTJu0DmLkZW1XWSo7kEI+4LSuxkZh13TiYJ mbfvyR1OS3Nmi8ivIVnPWm+Pn5OB6bT4h1hiV2j2zlYtHdIcDe23oYcUN9CoUPF1I6Se rjh9K8etdWd0gSvMvrsJ1XntS61in9p59FWNe4ojK6b6YvBR3kWYsz7MMGZsQ0D9mWoT DXyqyegwFMHPsFd2QFEc/LRy2urYgqSJR7ql8L3pMZ5VJO3/h/rNK0QLsNF+kclb/M0j fSA5GBwnTJj5QjcGlGopGB53xv29yBmdEkA5iMlK2TC8Tt1OJXXvu4rw6Y+h/cPjBF1r MFGQ== X-Gm-Message-State: AJIora9kA4dRzLpGOPxcPvq7CBoLPw7xJQWZKEb5qnYb5G0AaBWjSlG9 U/Jnw6LYOxFylHCA/L/qjrJK/LKaC3g0qWE5Lc6jCnT+Qd9UhtUX9QVnw5Ua/i6NEhZPnKoK3qo 6Nir/nLkQ3a0VONL/lrCdCrxK1JtiQXh9 X-Received: by 2002:a05:6214:21e5:b0:46d:82b5:b1a2 with SMTP id p5-20020a05621421e500b0046d82b5b1a2mr17181641qvj.116.1655684000418; Sun, 19 Jun 2022 17:13:20 -0700 (PDT) X-Google-Smtp-Source: AGRyM1u11rtrLY+g5M2nCrOAG+de9EQor4S+jtJsK4ufq12Bslo6XKYHwYbk+2okXdqgEXXhSaZqNjZta9YrIegta5M= X-Received: by 2002:a05:6214:21e5:b0:46d:82b5:b1a2 with SMTP id p5-20020a05621421e500b0046d82b5b1a2mr17181630qvj.116.1655684000127; Sun, 19 Jun 2022 17:13:20 -0700 (PDT) MIME-Version: 1.0 References: <20220603182143.692576-1-miquel.raynal@bootlin.com> <20220603182143.692576-2-miquel.raynal@bootlin.com> <20220606174319.0924f80d@xps-13> <20220607181608.609429cb@xps-13> <20220608154749.06b62d59@xps-13> <20220609175217.21a9acee@xps-13> <20220617171256.2261a99e@xps-13> In-Reply-To: <20220617171256.2261a99e@xps-13> From: Alexander Aring Date: Sun, 19 Jun 2022 20:13:08 -0400 Message-ID: Subject: Re: [PATCH wpan-next 1/6] net: ieee802154: Drop coordinator interface type To: Miquel Raynal Cc: Stefan Schmidt , Alexander Aring , linux-wpan - ML , David Girault , Romuald Despres , Frederic Blain , Nicolas Schodet , Thomas Petazzoni , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Network Development Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, On Fri, Jun 17, 2022 at 11:13 AM Miquel Raynal wrote: > > Hi Alex, > > aahringo@redhat.com wrote on Sat, 11 Jun 2022 08:23:41 -0400: > > > Hi, > > > > On Thu, Jun 9, 2022 at 11:52 AM Miquel Raynal wrote: > > > > > > Hi Alexander, > > > > > > aahringo@redhat.com wrote on Wed, 8 Jun 2022 21:56:53 -0400: > > > > > > > Hi, > > > > > > > > On Wed, Jun 8, 2022 at 9:47 AM Miquel Raynal wrote: > > > > > > > > > > Hi Alex, > > > > > > > > > > > > 3. coordinator (any $TYPE specific) userspace software > > > > > > > > > > > > > > May the main argument. Some coordinator specific user space daemon > > > > > > > does specific type handling (e.g. hostapd) maybe because some library > > > > > > > is required. It is a pain to deal with changing roles during the > > > > > > > lifetime of an interface and synchronize user space software with it. > > > > > > > We should keep in mind that some of those handlings will maybe be > > > > > > > moved to user space instead of doing it in the kernel. I am fine with > > > > > > > the solution now, but keep in mind to offer such a possibility. > > > > > > > > > > > > > > I think the above arguments are probably the same why wireless is > > > > > > > doing something similar and I would avoid running into issues or it's > > > > > > > really difficult to handle because you need to solve other Linux net > > > > > > > architecture handling at first. > > > > > > > > > > > > Yep. > > > > > > > > > > The spec makes a difference between "coordinator" and "PAN > > > > > coordinator", which one is the "coordinator" interface type supposed to > > > > > picture? I believe we are talking about being a "PAN coordinator", but > > > > > I want to be sure that we are aligned on the terms. > > > > > > > > > > > > > I think it depends what exactly the difference is. So far I see for > > > > address filtering it should be the same. Maybe this is an interface > > > > option then? > > > > > > The difference is that the PAN coordinator can decide to eg. refuse an > > > association, while the other coordinators, are just FFDs with no > > > specific decision making capability wrt the PAN itself, but have some > > > routing capabilities available for the upper layers. > > > > > > > As I said, if there is a behaviour "it can do xxx, but the spec > > doesn't give more information about it" this smells for me like things > > moving into the user space. This can also be done e.g. by a filtering > > mechanism, _just_ the user will configure how this filtering will look > > like. > > > > > The most I look into this, the less likely it is that the Linux stack > > > will drive an RFD. Do you think it's worth supporting them? Because if > > > we don't: > > > * NODE == FFD which acts as coordinator > > > * COORD == FFD which acts as the PAN coordinator > > > > > > > I thought that this is a kind of "transceiver type capability " e.g. I > > can imagine if it's only a "RFD" transceiver then you would be e.g. > > not able to set the address filter to coordinator capability. However > > I think that will never happen for a SoftMAC transceiver because why > > not adding a little bit silicon to provide that? People also can > > always have a co-processor and run the transceiver in promiscuous > > mode. E.g. atusb (which makes this transceiver poweful, because we > > have control over the firmware). > > > > For me node != coord, because the address filtering is different. As I > > mentioned in another mail "coordinator" vs "PAN coordinator" as > > described is what the user is doing here on top of it. > > > > > > > > > > > You are mixing things here with "role in the network" and what > > > > > > > > > the transceiver capability (RFD, FFD) is, which are two > > > > > > > > > different things. > > > > > > > > > > > > > > > > I don't think I am, however maybe our vision differ on what an > > > > > > > > interface should be. > > > > > > > > > > > > > > > > > You should use those defines and the user needs to create a new > > > > > > > > > interface type and probably have a different extended address > > > > > > > > > to act as a coordinator. > > > > > > > > > > > > > > > > Can't we just simply switch from coordinator to !coordinator > > > > > > > > (that's what I currently implemented)? Why would we need the user > > > > > > > > to create a new interface type *and* to provide a new address? > > > > > > > > > > > > > > > > Note that these are real questions that I am asking myself. I'm > > > > > > > > fine adapting my implementation, as long as I get the main idea. > > > > > > > > > > > > > > > > > > > > > > See above. > > > > > > > > > > > > That's okay for me. I will adapt my implementation to use the > > > > > > interface thing. In the mean time additional details about what a > > > > > > coordinator interface should do differently (above question) is > > > > > > welcome because this is not something I am really comfortable with. > > > > > > > > > > I've updated the implementation to use the IFACE_COORD interface and it > > > > > works fine, besides one question below. > > > > > > > > > > Also, I read the spec once again (soon I'll sleep with it) and > > > > > actually what I extracted is that: > > > > > > > > > > * A FFD, when turned on, will perform a scan, then associate to any PAN > > > > > it found (algorithm is beyond the spec) or otherwise create a PAN ID > > > > > and start its own PAN. In both cases, it finishes its setup by > > > > > starting to send beacons. > > > > > > > > > > > > > What does it mean "algorithm is beyond the spec" - build your own? > > > > > > This is really what is in the spec, I suppose it means "do what you > > > want in your use case". > > > > > > What I have in mind: when a device is powered on and detects two PANs, > > > well, it can join whichever it wants, but perhaps we should make the > > > decision based on the LQI information we have (the closer the better). > > > > > > > As I said in the other mail, this smells more and more for me to move > > this handling to user space. The kernel therefore supports operations > > to trigger the necessary steps (scan/assoc/etc.) > > > > > > > * A RFD will behave more or less the same, without the PAN creation > > > > > possibility of course. RFD-RX and RFD-TX are not required to support > > > > > any of that, I'll assume none of the scanning features is suitable > > > > > for them. > > > > > > > > > > I have a couple of questions however: > > > > > > > > > > - Creating an interface (let's call it wpancoord) out of wpan0 means > > > > > that two interfaces can be used in different ways and one can use > > > > > wpan0 as a node while using wpancoord as a PAN coordinator. Is that > > > > > really allowed? How should we prevent this from happening? > > > > > > > > > > > > > When the hardware does not support it, it should be forbidden. As most > > > > transceivers have only one address filter it should be forbidden > > > > then... but there exists a way to indeed have such a setup (which you > > > > probably don't need to think about). It's better to forbid something > > > > now, with the possibility later allowing it. So it should not break > > > > any existing behaviour. > > > > > > Done, thanks to the pointer you gave in the other mail. > > > > > > > > > > > > - Should the device always wait for the user(space) to provide the PAN > > > > > to associate to after the scan procedure right after the > > > > > add_interface()? (like an information that must be provided prior to > > > > > set the interface up?) > > > > > > > > > > - How does an orphan FFD should pick the PAN ID for a PAN creation? > > > > > Should we use a random number? Start from 0 upwards? Start from > > > > > 0xfffd downwards? Should the user always provide it? > > > > > > > > > > > > > I think this can be done all with some "fallback strategies" (build > > > > your own) if it's not given as a parameter. > > > > > > Ok, In case no PAN is found, and at creation no PAN ID is provided, we > > > can default to 0. > > > > > > > See me for other mails. (user space job) > > > > > > > - Should an FFD be able to create its own PAN on demand? Shall we > > > > > allow to do that at the creation of the new interface? > > > > > > > > > > > > > I thought the spec said "or otherwise"? That means if nothing can be > > > > found, create one? > > > > > > Ok, so we assume this is only at startup, fine. But then how to handle > > > the set_pan_id() call? I believe we can forbid any set_pan_id() command > > > to be run while the interface is up. That would ease the handling. > > > Unless I am missing something? > > > > > > > See my other mails (user space job). > > Ok then, I'll go with the following constraints in mind: > > SCAN (passive/active) (all devices) > - All devices are allowed to perform scans. > - The user decides when a scan must be performed, there is no > limitation on when to do a scan (but the interface must be up for > physical reasons). Yes, I think it should not have anything to do with interface limitation.... it needs to have an operating phy. However I can say more to this when I see code (but please don't provide me with any github repository, I mean here on the mailing list and not a more than 15 patches stack, Thanks.) You probably want to say on an user level "run scan for iface $FOO" but this is just to make it simpler. > PAN ID > - The user is responsible to set the PAN ID. This is currently the case and I don't see a reason to change it. > - Like several other parameters, the PAN ID can only be changed if the > iface is down. Which means the user might need to do: > link up > scan > link down > set params > link up Yes, changing this behaviour will break other things. > BEACON > - Coordinator interfaces only can send beacons. okay. > - Beacons can only be sent when part of a PAN (PAN ID != 0xffff). I guess that 0xffff means no pan is set and if no pan is set there is no pan? > - The choice of the beacon interval is up to the user, at any moment. > OTHER PARAMETERS I would say "okay", there might be an implementation detail about when it's effective. But is this not only required if doing such "passive" mode? > - The choice of the channel (page, etc) is free until the device is > associated to another, then it becomes fixed. > I would say no here, because if the user changes it it's their problem... it's required to be root for doing it and that should be enough to do idiot things? > ASSOCIATION (to be done) > - Device association/disassociation procedure is requested by the > user. This is similar like wireless is doing with assoc/deassoc to ap. > - Accepting new associations is up to the user (coordinator only). Again implementation details how this should be realized. > - If the device has no parent (was not associated to any device) it is > PAN coordinator and has additional rights regarding associations. > No idea what a "device' here is, did we not made a difference between "coordinator" vs "PAN coordinator" before and PAN is that thing which does some automatically scan/assoc operation and the other one not? I really have no idea what "device" here means. - Alex