Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752005AbbKIMvy (ORCPT ); Mon, 9 Nov 2015 07:51:54 -0500 Received: from casper.infradead.org ([85.118.1.10]:46153 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751161AbbKIMvx (ORCPT ); Mon, 9 Nov 2015 07:51:53 -0500 Date: Mon, 9 Nov 2015 13:51:47 +0100 From: Peter Zijlstra To: Vineet Gupta Cc: "gilf@ezchip.com" , "talz@ezchip.com" , "linux-kernel@vger.kernel.org" , "cmetcalf@ezchip.com" , Noam Camus , "linux-snps-arc@lists.infradead.org" Subject: Re: [PATCH v2 16/19] ARC: [plat-eznps] Use dedicated cpu_relax() Message-ID: <20151109125147.GU3604@twins.programming.kicks-ass.net> References: <1446297327-16298-1-git-send-email-noamc@ezchip.com> <1446893557-29748-17-git-send-email-noamc@ezchip.com> <20151109100503.GH17308@twins.programming.kicks-ass.net> <20151109104533.GT3604@twins.programming.kicks-ass.net> <5640912D.3010504@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5640912D.3010504@synopsys.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1541 Lines: 43 On Mon, Nov 09, 2015 at 05:57:25PM +0530, Vineet Gupta wrote: > From e29de8efa621b825891dcc744c84965b38f6b868 Mon Sep 17 00:00:00 2001 > From: Vineet Gupta > Date: Mon, 9 Nov 2015 17:48:34 +0530 > Subject: [PATCH] ARC: cpu_relax() to be compiler barrier even for UP > > cpu_relax() on ARC has been barrier only for SMP (and no-op for UP). Per > recent discussions, it is safer to make it a compiler barrier > unconditionally. > > Link: http://lkml.kernel.org/r/53A7D3AA.9020100@synopsys.com Acked-by: Peter Zijlstra (Intel) > Signed-off-by: Vineet Gupta > --- > arch/arc/include/asm/processor.h | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h > index 44545354e9e8..1d694c1ef6d6 100644 > --- a/arch/arc/include/asm/processor.h > +++ b/arch/arc/include/asm/processor.h > @@ -57,11 +57,7 @@ struct task_struct; > * A lot of busy-wait loops in SMP are based off of non-volatile data otherwise > * get optimised away by gcc > */ > -#ifdef CONFIG_SMP > #define cpu_relax() __asm__ __volatile__ ("" : : : "memory") > -#else > -#define cpu_relax() do { } while (0) > -#endif > > #define cpu_relax_lowlatency() cpu_relax() > > -- > 1.9.1 > -- 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/