From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id CAF2B1A05EC for ; Thu, 14 Aug 2014 16:19:10 +1000 (EST) Message-ID: <1407997135.5490.58.camel@pasglop> Subject: Re: [git pull] Please pull powerpc.git next branch From: Benjamin Herrenschmidt To: Linus Torvalds 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" Mime-Version: 1.0 Cc: linuxppc-dev , Linux Kernel list , Michael Ellerman List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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.