From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750900AbWJKJf0 (ORCPT ); Wed, 11 Oct 2006 05:35:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751024AbWJKJf0 (ORCPT ); Wed, 11 Oct 2006 05:35:26 -0400 Received: from nic.NetDirect.CA ([216.16.235.2]:64458 "EHLO rubicon.netdirect.ca") by vger.kernel.org with ESMTP id S1750900AbWJKJfZ (ORCPT ); Wed, 11 Oct 2006 05:35:25 -0400 X-Originating-Ip: 72.57.81.197 Date: Wed, 11 Oct 2006 05:34:12 -0400 (EDT) From: "Robert P. J. Day" X-X-Sender: rpjday@localhost.localdomain To: Steven Rostedt cc: Linux Kernel Mailing List Subject: Re: thoughts on potential cleanup of semaphores? In-Reply-To: <1160534524.13097.7.camel@localhost.localdomain> Message-ID: References: <1160534524.13097.7.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Net-Direct-Inc-MailScanner-Information: Please contact the ISP for more information X-Net-Direct-Inc-MailScanner: Found to be clean X-MailScanner-From: rpjday@mindspring.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Oct 2006, Steven Rostedt wrote: > > On Tue, 2006-10-10 at 12:00 -0400, Robert P. J. Day wrote: > > 1) can all instances of sema_init() in the header files be simplified > > based on the comment you can see in some of those header files? > > > > ======================== > > static inline void sema_init (struct semaphore *sem, int val) > > { > > /* > > * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); > > * > > * i'd rather use the more flexible initialization above, but sadly > > * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well. > > */ > > atomic_set(&sem->count, val); > > sem->sleepers = 0; > > init_waitqueue_head(&sem->wait); > > } > > ======================== > > > > one would think there's little value in retaining code that > > accommodates something as old as GCC 2.7.2.3, but i'm not the expert > > here. > > Well, I believe it's official, that we don't support GCC 2.7.2.3 anymore > anyway. ok, so a patch to simplify *all* of the above implementations of sema_init() to a single call to __SEMAPHORE_INITIALIZER() would not be out of line. i'll resubmit my earlier one, making sure it's based on the latest "git pull". > > and stepping back and looking at the bigger picture, it seems that > > the semaphore.h files across all architectures are *almost* identical, > > with a small number of differences, such as: > > All those asm statements :-) well, ok, i worded that badly. let me try again. at least the semaphore *interfaces* across all architectures seem to be almost identical, with the exception, of course, of the inline "asm" routines. but (and i know this idea is not going *anywhere*) when a routine in a header file is defined as inline and consists of a dozen assembler statements, wouldn't it make more sense to (dons asbestos suit here) have those routines be part of the *source* file and not the header file? i'm probably making more of this than it's worth but, as i was digging around in the semaphore implementations, it struck me that there was a lot of unnecessary duplication across the numerous semaphore.h files. is there no reasonable way to get rid of at least *some* of that? > > p.s. trying to condense all of the separate semaphore.h files > > into a single, configurable one would also solve the problem of > > incorrect documentation in some of them that is clearly the result > > of cut-and-paste. but i'm interested in what the experts have to > > say. > > But the meat in those files are in the down and up functions. Which > are all pretty much drastically different. All you would accomplish > is some standard initialization of the structure and sema_init. so perhaps the up and down functions represent the stuff that can be kept in arch-specific files, while the rest of semaphore.h is condensed to a single, cross-arch file. it still seems like there's lots of redundancy that can be eliminated here with very little effort. in defense of minimalism, rday