From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753255AbaHNGTO (ORCPT ); Thu, 14 Aug 2014 02:19:14 -0400 Received: from gate.crashing.org ([63.228.1.57]:48517 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751078AbaHNGTN (ORCPT ); Thu, 14 Aug 2014 02:19:13 -0400 Message-ID: <1407997135.5490.58.camel@pasglop> Subject: Re: [git pull] Please pull powerpc.git next branch From: Benjamin Herrenschmidt To: Linus Torvalds Cc: linuxppc-dev , Linux Kernel list , Michael Ellerman Date: Thu, 14 Aug 2014 16:18:55 +1000 In-Reply-To: <1407996977.5490.56.camel@pasglop> References: <1407996977.5490.56.camel@pasglop> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2014-08-14 at 16:16 +1000, Benjamin Herrenschmidt wrote: > Another interesting one in the "OMG" category is the series from Michael > adding memory barriers to spin_is_locked(). That's also the result of many > days of debugging to figure out why the semaphore code would occasionally > crash in ways that made no sense. It ended up being some creative lock > stacking that was defeated by the fact that our locks allow a load inside > the locked section to be re-ordered with the load of the lock value itself > (I'm still of two mind about whether to kill that once and for all by putting > a heavier barrier back into our lock implementation...). The fixes come with > a long explanation in the cset comments, feel free to read it if you feel > like having a headache today. Talking of which, I should have tagged that for stable... I'll forward them separately when you've pulled. Michael: If I miss this while I'm away next week, can you take care of it ? Cheers, Ben.