From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751417AbWEDG6F (ORCPT ); Thu, 4 May 2006 02:58:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751418AbWEDG6F (ORCPT ); Thu, 4 May 2006 02:58:05 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:35050 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1751417AbWEDG6D (ORCPT ); Thu, 4 May 2006 02:58:03 -0400 Subject: Re: limits / PIPE_BUF? From: Arjan van de Ven To: Vadim Lobanov Cc: linux-kernel@vger.kernel.org In-Reply-To: References: Content-Type: text/plain Date: Thu, 04 May 2006 08:58:01 +0200 Message-Id: <1146725882.3101.11.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2006-05-03 at 22:55 -0700, Vadim Lobanov wrote: > Hi, > > I was reading through the include/linux/limits.h file in order to > generate a cleanup patch for it -- a large number of #defines within > that file are no longer being used, as I surmise that they are simply > remnants of earlier implementations. > > A snippet from include/linux/limits.h: > #define PIPE_BUF 4096 /* # bytes in atomic write to a pipe */ > > PIPE_BUF is a bit of an oddity. It is defined there, then redefined in > the arm header files, even though those header files are never included > anywhere. Also, PIPE_BUF is never referenced by name in any of the Linux > code. And yet, it is still being mentioned in some Big And Scary > Warnings (tm): fs/autofs4/waitq.c or include/linux/pipe_fs_i.h, for > example. it's for userland to tell it what the size of the atomic pipe operations we can do is.