Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261438AbVCVQrx (ORCPT ); Tue, 22 Mar 2005 11:47:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261429AbVCVQrx (ORCPT ); Tue, 22 Mar 2005 11:47:53 -0500 Received: from keetweej.xs4all.nl ([213.84.46.114]:58854 "EHLO keetweej.vanheusden.com") by vger.kernel.org with ESMTP id S261441AbVCVQrM (ORCPT ); Tue, 22 Mar 2005 11:47:12 -0500 Date: Tue, 22 Mar 2005 17:47:10 +0100 To: linux-kernel@vger.kernel.org Subject: [PATCH] optimize check in port-allocation code Message-ID: <20050322164709.GC15960@vanheusden.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PEkEgRdBLZYkpbX2" Content-Disposition: inline Organization: www.unixexpert.nl X-Chameleon-Return-To: folkert@vanheusden.com X-Xfmail-Return-To: folkert@vanheusden.com X-Phonenumber: +31-6-41278122 X-URL: http://www.vanheusden.com/ X-PGP-KeyID: 1F28D8AE X-GPG-fingerprint: AC89 09CE 41F2 00B4 FCF2 B174 3019 0E8C 1F28 D8AE X-Key: http://pgp.surfnet.nl:11371/pks/lookup?op=get&search=0x1F28D8AE Read-Receipt-To: Reply-By: Tue Mar 22 15:34:18 CET 2005 X-MSMail-Priority: High User-Agent: Mutt/1.5.6+20040907i From: folkert@vanheusden.com (Folkert van Heusden) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3793 Lines: 107 --PEkEgRdBLZYkpbX2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi, In the 2.6.11 code, I found this: static int tcp_v6_get_port(struct sock *sk, unsigned short snum) also in: static int tcp_v4_get_port(struct sock *sk, unsigned short snum) { ... if (snum == 0) { int low = sysctl_local_port_range[0]; int high = sysctl_local_port_range[1]; spin_lock(&tcp_portalloc_lock); rover = tcp_port_rover; do { rover++; if ((rover < low) || (rover > high)) rover = low; That 'rover < low' check is redundant? ints are bigger then the maximum portnumber (65535) so when rover++ gets too high, the check for 'rover > high' will truncate it to low (in the next line) waaay before the int itself wraps. It is needed because tcp_port_rover might be < low before the function starts, in that case the check for high) + if (rover > high) rover = low; head = &tcp_bhash[tcp_bhashfn(rover)]; spin_lock(&head->lock); diff -uNr net/ipv6/tcp_ipv6.c.org net/ipv6/tcp_ipv6.c --- net/ipv6/tcp_ipv6.c.org 2005-03-04 22:41:44.043007791 +0100 +++ net/ipv6/tcp_ipv6.c 2005-03-04 22:42:17.604728073 +0100 @@ -139,9 +139,12 @@ int rover; spin_lock(&tcp_portalloc_lock); - rover = tcp_port_rover; + if (tcp_port_rover < low) + rover = low; + else + rover = tcp_port_rover; do { rover++; - if ((rover < low) || (rover > high)) + if (rover > high) rover = low; head = &tcp_bhash[tcp_bhashfn(rover)]; spin_lock(&head->lock); Signed-off-by: Folkert van Heusden Folkert van Heusden Auto te koop! Zie: http://www.vanheusden.com/daihatsu.php Op zoek naar een IT of Finance baan? Mail me voor de mogelijkheden! +------------------------------------------------------------------+ |UNIX admin? Then give MultiTail (http://vanheusden.com/multitail/)| |a try, it brings monitoring logfiles to a different level! See | |http://vanheusden.com/multitail/features.html for a feature list. | +------------------------------------------= www.unixsoftware.nl =-+ Phone: +31-6-41278122, PGP-key: 1F28D8AE Get your PGP/GPG key signed at www.biglumber.com! --PEkEgRdBLZYkpbX2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFCQEwNMBkOjB8o2K4RAgilAKCIrLEBM9wBuXk1sCrNpw6UynPPpwCfbHNh NgWJl3Ogu8tiCrVeko3GCPQ= =PTGy -----END PGP SIGNATURE----- --PEkEgRdBLZYkpbX2-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/