Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756100Ab1BUQVD (ORCPT ); Mon, 21 Feb 2011 11:21:03 -0500 Received: from casper.infradead.org ([85.118.1.10]:57644 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755950Ab1BUQVB convert rfc822-to-8bit (ORCPT ); Mon, 21 Feb 2011 11:21:01 -0500 Subject: Re: [PATCH v2 1/1] headers: fix circular dependency between linux/sched.h and linux/wait.h From: Peter Zijlstra To: David Cohen Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, linux-omap@vger.kernel.org, linux-media@vger.kernel.org, Alexey Dobriyan , Oleg Nesterov In-Reply-To: References: <1298299131-17695-1-git-send-email-dacohen@gmail.com> <1298299131-17695-2-git-send-email-dacohen@gmail.com> <1298303677.24121.1.camel@twins> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Mon, 21 Feb 2011 17:20:45 +0100 Message-ID: <1298305245.24121.7.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2539 Lines: 50 On Mon, 2011-02-21 at 18:03 +0200, David Cohen wrote: > On Mon, Feb 21, 2011 at 5:54 PM, Peter Zijlstra wrote: > > On Mon, 2011-02-21 at 16:38 +0200, David Cohen wrote: > >> Currently sched.h and wait.h have circular dependency between both. > >> wait.h defines macros wake_up*() which use macros TASK_* defined by > >> sched.h. But as sched.h indirectly includes wait.h, such wait.h header > >> file can't include sched.h too. The side effect is when some file > >> includes wait.h and tries to use its wake_up*() macros, it's necessary > >> to include sched.h also. > >> This patch moves all TASK_* macros from linux/sched.h to a new header > >> file linux/task_state.h. This way, both sched.h and wait.h can include > >> task_state.h and fix the circular dependency. No need to include sched.h > >> anymore when wake_up*() macros are used. > > > > I think Alexey already told you what you done wrong. > > > > Also, I really don't like the task_state.h header, it assumes a lot of > > things it doesn't include itself and only works because its using macros > > and not inlines at it probably should. > > Like wait.h I'd say. The main issue is wait.h uses TASK_* macros but > cannot properly include sched.h as it would create a circular > dependency. So a file including wait.h is able to compile because the > dependency of sched.h relies on wake_up*() macros and it's not always > used. > We can still drop everything else from task_state.h but the TASK_* > macros and then the problem you just pointed out won't exist anymore. > What do you think about it? I'd much rather see a real cleanup.. eg. remove the need for sched.h to include wait.h. afaict its needed because struct signal_struct and struct sighand_struct include a wait_queue_head_t. The inclusion seems to come through completion.h, but afaict we don't actually need to include completion.h because all we have is a pointer to a completion, which is perfectly fine with an incomplete type. This all would suggest we move the signal bits into their own header (include/linux/signal.h already exists and seems inviting). And then make sched.c include signal.h and completion.h. But then, there might be a 'good' reason these signal bits live in sched.h and not on their own, but I wouldn't know.. -- 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/