From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753760AbcAZVPB (ORCPT ); Tue, 26 Jan 2016 16:15:01 -0500 Received: from mail.skyhub.de ([78.46.96.112]:56876 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751021AbcAZVMQ (ORCPT ); Tue, 26 Jan 2016 16:12:16 -0500 From: Borislav Petkov To: Ingo Molnar Cc: LKML Subject: [PATCH 03/10] x86/asm: Tweak the comment about wmb() use for IO Date: Tue, 26 Jan 2016 22:12:03 +0100 Message-Id: <1453842730-28463-4-git-send-email-bp@alien8.de> X-Mailer: git-send-email 2.3.5 In-Reply-To: <1453842730-28463-1-git-send-email-bp@alien8.de> References: <1453842730-28463-1-git-send-email-bp@alien8.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Michael S. Tsirkin" On x86, we *do* still use the non-nop rmb()/wmb() for IO barriers, but even that is generally questionable. Leave them around for historical reasons, unless somebody can point to a case where they care about the performance. Tweak the comment so people don't think they are strictly required in all cases. Signed-off-by: Michael S. Tsirkin Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Davidlohr Bueso Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Linus Torvalds Cc: "Paul E. McKenney" Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: virtualization Link: http://lkml.kernel.org/r/1452715911-12067-4-git-send-email-mst@redhat.com Signed-off-by: Borislav Petkov --- arch/x86/include/asm/barrier.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h index d2aa66a3a4b5..4f95b2affd88 100644 --- a/arch/x86/include/asm/barrier.h +++ b/arch/x86/include/asm/barrier.h @@ -6,8 +6,8 @@ /* * Force strict CPU ordering. - * And yes, this is required on UP too when we're talking - * to devices. + * + * And yes, this might be required on UP too when we're talking to devices. */ #ifdef CONFIG_X86_32 -- 2.3.5