From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758019Ab0BDV43 (ORCPT ); Thu, 4 Feb 2010 16:56:29 -0500 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:51454 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752139Ab0BDV40 (ORCPT ); Thu, 4 Feb 2010 16:56:26 -0500 Date: Thu, 04 Feb 2010 13:56:39 -0800 (PST) Message-Id: <20100204.135639.69720709.davem@davemloft.net> To: penguin-kernel@I-love.SAKURA.ne.jp Cc: opurdila@ixiacom.com, amwang@redhat.com, linux-kernel@vger.kernel.org, eric.dumazet@gmail.com, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, nhorman@tuxdriver.com, linux-sctp@vger.kernel.org Subject: Re: [RFC Patch] net: reserve ports for applications using fixed port numbers From: David Miller In-Reply-To: <201002050645.CEC95380.MLOtOVFFHSFOQJ@I-love.SAKURA.ne.jp> References: <20100204.094110.64247447.davem@davemloft.net> <201002042015.51092.opurdila@ixiacom.com> <201002050645.CEC95380.MLOtOVFFHSFOQJ@I-love.SAKURA.ne.jp> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tetsuo Handa Date: Fri, 5 Feb 2010 06:45:28 +0900 > Octavian Purdila wrote: >> >> int inet_is_reserved_local_port(int port) >> { >> if (test_bit(port, reserved_ports)) >> return 1; >> return 0; >> } >> > Above check is exactly what I'm doing in the LSM hook. But his version can be done inline in 2 or 3 instructions. An LSM hook will result in an indirect function call, all live registers spilled to the stack, then all of those reloaded when the function returns. It will be much more expensive.