From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933761Ab2DLXBw (ORCPT ); Thu, 12 Apr 2012 19:01:52 -0400 Received: from www.linutronix.de ([62.245.132.108]:39057 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932792Ab2DLXBv (ORCPT ); Thu, 12 Apr 2012 19:01:51 -0400 Date: Fri, 13 Apr 2012 01:01:46 +0200 (CEST) From: Thomas Gleixner To: Linus Torvalds cc: Sasikantha Babu , Andrew Morton , LKML , Ingo Molnar Subject: Re: [GIT pull] timer fixes for 3.4 In-Reply-To: Message-ID: References: User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 12 Apr 2012, Linus Torvalds wrote: > On Thu, Apr 12, 2012 at 3:39 PM, Thomas Gleixner wrote: > >> > >> That said, would people actually *report* those messages? > >> > >> In general, for things like this, it's probably better to just make > >> the change (especially if you have several distros you can test), and > >> then add a printk_once() for the case that changed. Then, if people > > > > I changed it to a printk_once() already. > > No, I meant that the whole message should probably have been added > when actually changing the semantics. > > If you have good reason to believe that some ABI change (a) does not > actually have any reason to break anything and (b) worth doing, then I > think it should just have been done (but during the merge window only, > of course). > > And if (a) or (b) aren't true, then we're not going to change the ABI > at all, so the whole point is moot. > > The printk_once (or, for that case WARN_ON_ONCE() may even be > worthwhile) would then just be a "oops, we were wrong" kind of > message, and would just mean that the commit would be reverted. > > I think the whole "let's deprecate this six months into the future" is > unnecessary. Yes, it may well be worth doing for something with bigger > consequences, but I think that for something like this, it's just > overthinking the issue. > > If it really is something we want to fix, I think it's much better to > just say "let's fix it, and if somebody notices, we'll have to go > back". The printk_once or WARN_ON is then just a polite way to avoid > having people have to bisect to it etc if it's subtle (and then we > would plan to remove *that* later). Fair enough. Though last time I tried to do that (IIRC, it was a sanity check on a timespec) I was forced to go the deprecation way .... Times are changing :) tglx