Date: Mon, 11 Jun 2001 14:20:31 -0700 From: Brooks Davis <brooks@one-eyed-alien.net> To: Hajimu UMEMOTO <ume@mahoroba.org> Cc: hackers@FreeBSD.ORG, brian@Awfulhak.org, phk@critter.freebsd.dk, arch@FreeBSD.ORG Subject: Re: cloning network interfaces Message-ID: <20010611142030.A15283@Odin.AC.HMC.Edu> In-Reply-To: <20010610.232907.74740159.ume@mahoroba.org>; from ume@mahoroba.org on Sun, Jun 10, 2001 at 11:29:07PM %2B0900 References: <200106071119.f57BJr766008@hak.lan.Awfulhak.org> <20010607164812.A32379@Odin.AC.HMC.Edu> <20010608191904.A18847@Odin.AC.HMC.Edu> <20010610.232907.74740159.ume@mahoroba.org>
next in thread | previous in thread | raw e-mail | index | archive | help
--BOKacYhQ+x31HxR3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Jun 10, 2001 at 11:29:07PM +0900, Hajimu UMEMOTO wrote: > I think it is not BSD network way. Recent NetBSD has network > interface cloning. It uses SIOCIFCREATE and SIOCIFDESTROY. It may > good to port it to FreeBSD. I've looked it over and I generally like it. There is one problem though. That's the requirement that you use static units. The problem with this is that it forces you to implement free unit scanning in userland if you just want to create a unit and don't care what it is. If you have to do this, and things are being changed at any kind of significant rate, you have race condition between scanning the interface list for a free unit and trying to allocate it. This race can theoreticaly lead to starvation. My proposed solution is threefold. First, change the ifc_create pointer's type to: int (*ifc_create)(struct if_clone *, int *); so you can return a unit if the caller requests a wildcard unit (by passing -1). Second, move unit management in to the driver rather then just using ifunit in if_clone_create. Drivers could choose to implement wildcarding or not and if not could simply use ifunit for their test. Third, make if_clone_lookup treat names like "gif#" as a wildcard request and set unit to -1 as appropriate. These changes break compatability with NetBSD slightly, but it's just a few lines to convert an existing NetBSD clone_create handler to this style and it could easily be handled with #ifdef's. Thoughts, comments, objections? -- Brooks --=20 Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 --BOKacYhQ+x31HxR3 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE7JTYdXY6L6fI4GtQRAjwhAKCgP7XmJFS0ccQ16Dm4OLdrnXI0DwCeKb3p qJxw/Rk9OAT8cAiWx7hI3uQ= =5RL0 -----END PGP SIGNATURE----- --BOKacYhQ+x31HxR3-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20010611142030.A15283>