From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757048Ab3JKH0c (ORCPT ); Fri, 11 Oct 2013 03:26:32 -0400 Received: from mail-ea0-f181.google.com ([209.85.215.181]:60480 "EHLO mail-ea0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752945Ab3JKH0b (ORCPT ); Fri, 11 Oct 2013 03:26:31 -0400 Date: Fri, 11 Oct 2013 09:26:27 +0200 From: Ingo Molnar To: "Paul E. McKenney" Cc: Peter Zijlstra , Ingo Molnar , Oleg Nesterov , Linus Torvalds , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/16] sched/wait: Collapse __wait_event macros -v5 Message-ID: <20131011072627.GA9514@gmail.com> References: <20131008204056.GR5790@linux.vnet.ibm.com> <20131009032843.GA12970@linux.vnet.ibm.com> <20131009033502.GA14017@linux.vnet.ibm.com> <20131009060806.GC7664@gmail.com> <20131009142123.GT5790@linux.vnet.ibm.com> <20131010025904.GA4891@linux.vnet.ibm.com> <20131010080501.GA18481@gmail.com> <20131010171135.GL5790@linux.vnet.ibm.com> <20131010173937.GD26430@gmail.com> <20131010185819.GP5790@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131010185819.GP5790@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Paul E. McKenney wrote: > > So, I think this code lives within kernel/params.c. Might be fixable? > > But of course! I was just trying to be lazy. ;-) > > I could imagine adding a filename field to struct kernel_param that was > initialized with __FILE__, then making something like parameq() that did > the appropriate comparison allowing any match starting after a "/" and > ignoring the trailing ".h" or ".c", and then calling that from > parse_one() along with current parameq(). There doesn't seem to be any > point for doing the same to do_early_param(). > > There would be a few surprises with this approach, for example, > rcu_idle_gp_delay and rcu_idle_lazy_gp_delay, which are defined in > kernel/rcu/tree_plugin.h, would be: > > tree_plugin.rcu_idle_gp_delay=4 > tree_plugin.rcu_idle_lazy_gp_delay=6000 > > or: > > rcu/tree_plugin.rcu_idle_gp_delay=4 > rcu/tree_plugin.rcu_idle_lazy_gp_delay=6000 > > or: > > kernel/rcu/tree_plugin.rcu_idle_gp_delay=4 > kernel/rcu/tree_plugin.rcu_idle_lazy_gp_delay=6000 > > or I suppose even: > > linux-rcu/kernel/rcu/tree_plugin.rcu_idle_gp_delay=4 > linux-rcu/kernel/rcu/tree_plugin.rcu_idle_lazy_gp_delay=6000 > > instead of (say): > > kernel/rcu/tree.rcu_idle_gp_delay=4 > kernel/rcu/tree.rcu_idle_lazy_gp_delay=6000 > > This could of course also be fixed by comparing the filename up to the > last "/" followed by the current parameter name. Or, as Peter Zijlstra > suggested, by manually expanding kernel/rcu/tree_plugin.h into > kernel/rcu/tree.c. > > Or I could use the non-standard __BASE_FILE__ instead of __FILE__, which > expands to .../kernel/rcu/tree.c. LLVM seems to define this as well, so > should be OK to use. > > So it doesn't look too horrible. (Famous last words...) Hm, I'm not so sure about the long names, for the following reasons: strings like 'kernel/rcu/tree_plugin.' might mean a lot to us kernel developers - less to sysadmins and users who would want to utilize them. There's also a typo danger with overly long parameters and the parameter parser is not very intelligent about seeing the intent of the user. So I think while rcu/tree.val would be useful syntax, going above that, especially with auto-generated file names (and file names can change) would be overdoing it a bit :-/ Thanks, Ingo