Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751615AbaANRJF (ORCPT ); Tue, 14 Jan 2014 12:09:05 -0500 Received: from mail-qe0-f51.google.com ([209.85.128.51]:63778 "EHLO mail-qe0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751351AbaANRJC (ORCPT ); Tue, 14 Jan 2014 12:09:02 -0500 MIME-Version: 1.0 In-Reply-To: <20140114110307.GW7572@laptop.programming.kicks-ass.net> References: <52D353C8.4000000@numascale.com> <52D4172E.6030706@hp.com> <52D4A0C7.5070601@numascale.com> <20140114110307.GW7572@laptop.programming.kicks-ass.net> From: Matt Turner Date: Tue, 14 Jan 2014 09:08:41 -0800 Message-ID: Subject: Re: [PATCH v8 4/4] qrwlock: Use smp_store_release() in write_unlock() To: Peter Zijlstra Cc: Daniel J Blueman , Waiman Long , "Paul E. McKenney" , Linux Kernel , Richard Henderson , Ivan Kokshaysky , Linus Torvalds Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 14, 2014 at 3:03 AM, Peter Zijlstra wrote: > On Tue, Jan 14, 2014 at 10:28:23AM +0800, Daniel J Blueman wrote: >> >Peter, >> > >> >I found out that the build failure was caused by the fact that the >> >__native_word() macro (used internally by compiletime_assert_atomic()) >> >allows only a size of 4 or 8 for x86-64. The data type that I used is a >> >byte. Is there a reason why byte and short are not considered native? >> >> It seems likely it was implemented like that since there was no existing >> need; long can be relied on as the largest native type, so this should >> suffice and works here: > > There's Alphas that cannot actually atomically adres a byte; I do not > konw if Linux cares about them, but if it does, we cannot in fact rely > on this in generic primitives like this. That's right, and thanks for the heads-up. Alpha can only address 4 and 8 bytes atomically. (LDL_L, LDQ_L, STL_C, STQ_C). The Byte-Word extension in EV56 doesn't add new atomics, so in fact no Alphas can address < 4 bytes atomically. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/