From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Berg Subject: Re: multicasting netlink messages to groups > 31 from userspace Date: Wed, 04 Jul 2007 16:38:03 +0200 Message-ID: <1183559883.3812.42.camel@johannes.berg> References: <1183492286.4021.21.camel@johannes.berg> <468BAADC.4030203@trash.net> <1183558702.3812.33.camel@johannes.berg> <468BAF10.6080208@trash.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-B8tNGcRz3jR/phLEYukW" Cc: netdev , jamal , Thomas Graf To: Patrick McHardy Return-path: Received: from crystal.sipsolutions.net ([195.210.38.204]:56573 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759760AbXGDOhK (ORCPT ); Wed, 4 Jul 2007 10:37:10 -0400 In-Reply-To: <468BAF10.6080208@trash.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org --=-B8tNGcRz3jR/phLEYukW Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2007-07-04 at 16:30 +0200, Patrick McHardy wrote: [...] > The kernel doesn't have any multicast listeners (yet). Right. > I wonder if thats really a good idea to use multicast for device > configuration. Unicast transmissions from userspace to kernel > are reliable when you don't use MSG_DONTWAIT. For multicasts > doing the same would mean blocking on each receiver when the > receive queue is full. That's a good point actually. Are transmissions from userspace to userspace also reliable in that case? In fact, we haven't quite decided yet whether we want all configuration to be via netlink. I strongly prefer this, but other people say that userspace<->userspace communication is nothing that nl80211 should be involved in. What I initially wanted was to publish something like "Device wlan0 is managed by netlink pid 12345" (or 0 if the kernel is doing it) and then configuration would be "send to ". However, that got me into problems when trying to determine "is the process owning netlink pid 12345 still alive" at which point Herbert suggested the use of multicast groups (and doing the exclusion "only one manager per netdev" in userspace instead of the kernel). johannes --=-B8tNGcRz3jR/phLEYukW Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Comment: Johannes Berg (powerbook) iD8DBQBGi7DL/ETPhpq3jKURAr9tAJ4l03R00QZEzcQTgKd+XHgqhPUc6QCghDNa vhvk3Pu8EfpheZ9gTVzPkQM= =SU1N -----END PGP SIGNATURE----- --=-B8tNGcRz3jR/phLEYukW--