Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757797Ab1FPMRk (ORCPT ); Thu, 16 Jun 2011 08:17:40 -0400 Received: from relay1.sgi.com ([192.48.179.29]:55600 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757334Ab1FPMO7 (ORCPT ); Thu, 16 Jun 2011 08:14:59 -0400 To: linux-kernel@vger.kernel.org Subject: [PATCH 1/8 v3] x86, UV: smp_processor_id in a preemptable region Cc: mingo@elte.hu Message-Id: From: Cliff Wickman Date: Thu, 16 Jun 2011 07:16:11 -0500 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1280 Lines: 39 From: Cliff Wickman Calling smp_processor_id() from within a preemptable region will issue a warning if DEBUG_PREEMPT is set. The calls to get_cpu()/put_cpu() bound the region where the return cpu number is actually used and make it non-preemptable. A DEBUG_PREEMPT warning is prevented. UV does not support cpu hotplug yet, but this is a step toward that ability. Diffed against 3.0.0-rc3 Signed-off-by: Cliff Wickman --- arch/x86/platform/uv/tlb_uv.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) Index: linux/arch/x86/platform/uv/tlb_uv.c =================================================================== --- linux.orig/arch/x86/platform/uv/tlb_uv.c +++ linux/arch/x86/platform/uv/tlb_uv.c @@ -1334,9 +1334,10 @@ static ssize_t tunables_write(struct fil instr[count] = '\0'; - bcp = &per_cpu(bau_control, smp_processor_id()); - + cpu = get_cpu(); + bcp = &per_cpu(bau_control, cpu); ret = parse_tunables_write(bcp, instr, count); + put_cpu(); if (ret) return ret; -- 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/