From patchwork Thu Dec 31 19:09:47 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 7937611 X-Patchwork-Delegate: geert@linux-m68k.org Return-Path: X-Original-To: patchwork-linux-sh@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A50B0BEEE5 for ; Thu, 31 Dec 2015 19:11:24 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E2B542049C for ; Thu, 31 Dec 2015 19:11:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71F8D20481 for ; Thu, 31 Dec 2015 19:11:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754940AbbLaTJ7 (ORCPT ); Thu, 31 Dec 2015 14:09:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33552 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754910AbbLaTJy (ORCPT ); Thu, 31 Dec 2015 14:09:54 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 3ED3CC0B7E04; Thu, 31 Dec 2015 19:09:54 +0000 (UTC) Received: from redhat.com (vpn1-7-165.ams2.redhat.com [10.36.7.165]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id tBVJ9lnG024053; Thu, 31 Dec 2015 14:09:48 -0500 Date: Thu, 31 Dec 2015 21:09:47 +0200 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , virtualization@lists.linux-foundation.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , David Miller , linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, x86@kernel.org, user-mode-linux-devel@lists.sourceforge.net, adi-buildroot-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, xen-devel@lists.xenproject.org, Ingo Molnar Subject: [PATCH v2 31/32] sh: support a 2-byte smp_store_mb Message-ID: <1451572003-2440-32-git-send-email-mst@redhat.com> References: <1451572003-2440-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1451572003-2440-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP At the moment, xchg on sh only supports 4 and 1 byte values, so using it from smp_store_mb means attempts to store a 2 byte value using this macro fail. And happens to be exactly what virtio drivers want to do. Check size and fall back to a slower, but safe, WRITE_ONCE+smp_mb. Signed-off-by: Michael S. Tsirkin --- arch/sh/include/asm/barrier.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/sh/include/asm/barrier.h b/arch/sh/include/asm/barrier.h index f887c64..0cc5735 100644 --- a/arch/sh/include/asm/barrier.h +++ b/arch/sh/include/asm/barrier.h @@ -32,7 +32,15 @@ #define ctrl_barrier() __asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop") #endif -#define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0) +#define __smp_store_mb(var, value) do { \ + if (sizeof(var) != 4 && sizeof(var) != 1) { \ + WRITE_ONCE(var, value); \ + __smp_mb(); \ + } else { \ + (void)xchg(&var, value); \ + } \ +} while (0) + #define smp_store_mb(var, value) __smp_store_mb(var, value) #include