From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751369AbWEDFze (ORCPT ); Thu, 4 May 2006 01:55:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751401AbWEDFze (ORCPT ); Thu, 4 May 2006 01:55:34 -0400 Received: from mail2.sea5.speakeasy.net ([69.17.117.4]:33469 "EHLO mail2.sea5.speakeasy.net") by vger.kernel.org with ESMTP id S1751369AbWEDFze (ORCPT ); Thu, 4 May 2006 01:55:34 -0400 Date: Wed, 3 May 2006 22:55:32 -0700 (PDT) From: Vadim Lobanov To: linux-kernel@vger.kernel.org Subject: limits / PIPE_BUF? Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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. What's the deal with PIPE_BUF? Is its value used in the code indirectly, so that more comments would help make this fact obvious? Or is it now deprecated, and therefore a viable target for include/linux/limits.h cleanups? - Vadim Lobanov