Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752670AbdGGT6b (ORCPT ); Fri, 7 Jul 2017 15:58:31 -0400 Received: from mail-oi0-f44.google.com ([209.85.218.44]:36548 "EHLO mail-oi0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751089AbdGGT61 (ORCPT ); Fri, 7 Jul 2017 15:58:27 -0400 MIME-Version: 1.0 In-Reply-To: <20170705020635.GD11168@linux-80c1.suse> References: <20170614222017.14653-1-mcgrof@kernel.org> <20170614222017.14653-3-mcgrof@kernel.org> <20170629125402.GH26046@kroah.com> <20170629133530.GA14747@kroah.com> <20170629174046.GC3954@linux-80c1.suse> <20170629183339.GD3954@linux-80c1.suse> <20170705020635.GD11168@linux-80c1.suse> From: Linus Torvalds Date: Fri, 7 Jul 2017 12:58:26 -0700 X-Google-Sender-Auth: Rws5rV0MdWaBZDG28luaddn7Lzg Message-ID: Subject: Re: [PATCH 2/4] swait: add the missing killable swaits To: Davidlohr Bueso Cc: Thomas Gleixner , Greg KH , "Luis R. Rodriguez" , Martin Fuzzey , "Eric W. Biederman" , Dmitry Torokhov , Daniel Wagner , David Woodhouse , jewalt@lgsinnovations.com, =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , Arend Van Spriel , "Rafael J. Wysocki" , "Li, Yi" , atull@kernel.org, Moritz Fischer , Petr Mladek , Johannes Berg , Emmanuel Grumbach , "Coelho, Luciano" , Kalle Valo , Andrew Lutomirski , Kees Cook , "AKASHI, Takahiro" , David Howells , Peter Jones , Hans de Goede , Alan Cox , "Theodore Ts'o" , Michael Kerrisk , Paul Gortmaker , Marcelo Tosatti , Matthew Wilcox , Linux API , linux-fsdevel , Linux Kernel Mailing List , "stable # 4 . 6" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1467 Lines: 47 On Tue, Jul 4, 2017 at 7:06 PM, Davidlohr Bueso wrote: > > So here's something that boots and builds a kernel. Any thoughts? This patch ios just nasty crap. Sorry. It has random whitespace changfes that look entirely unrelated to trhe actual real meat of the patch, and that actually make whitespace *worse*. WHY? That alone should just mean that this patch needs to be thrown away and never ever looked at again. But also, this is fundamentally garbage. Exactly for the same reasons that the swait interfaces were fundamentally broken. It *looks* like it works on regular wait queues, and people can start using it that way, but it actually doesn't have the right semantics at all. The new "lockless" function ONLY works if you don't have a private wakeup function. So it completely changes the semantics of "wake_up_all()". It used to be that "wake_up_all()" did what the name suggested. With this patch, "wake_up_all()" will not cause random kernel oopses or memory corruption if you use any of the more specialized wakeup functions Guys, STOP DOING SHIT LIKE THIS! The swake interface was incredible crap, with bad semantics that confused people, and bad performance too. Don't make the normal wait-queues have similar idiotic problems. So no, this is not only NAK'ed, the whole approach is pure and utter shit and this needs to be buried deep and forgotten about so that it never ever comes back to life. Linus