Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754410AbbG3SgD (ORCPT ); Thu, 30 Jul 2015 14:36:03 -0400 Received: from e06smtp11.uk.ibm.com ([195.75.94.107]:49159 "EHLO e06smtp11.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752999AbbG3SgB (ORCPT ); Thu, 30 Jul 2015 14:36:01 -0400 X-Helo: d06dlp01.portsmouth.uk.ibm.com X-MailFrom: holzheu@linux.vnet.ibm.com X-RcptTo: linux-s390@vger.kernel.org From: Michael Holzheu To: Greg Kroah-Hartman Cc: Martin Schwidefsky , Heiko Carstens , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: [RFC PATCH] drivers/base: use cpu->node_id for from_nid Date: Thu, 30 Jul 2015 20:35:51 +0200 Message-Id: <1438281351-56556-1-git-send-email-holzheu@linux.vnet.ibm.com> X-Mailer: git-send-email 2.3.8 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15073018-0041-0000-0000-00000545D510 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1835 Lines: 56 Hello Greg, Is it possible to use "from_nid = cpu->node_id"? Background: I am currently working on (fake) NUMA support for s390. At startup, for "deconfigured" CPUs, we don't know to which nodes the CPUs belong. Therefore we always return node 0 for cpu_to_node(). For each present CPU the register_cpu() function is called which sets an initial NUMA node via cpu_to_node(), which is then first node 0 for "deconfigured" CPUs on s390. After we "configure" a CPU we know to which node it belongs. Then when setting a CPU online, the following is done in cpu_subsys_online(): from_nid = cpu_to_node(cpuid); -> we return node x cpu_up(cpuid); to_nid = cpu_to_node(cpuid); -> we return node x if (from_nid != to_nid) -> x != x -> false change_cpu_under_node(cpu, from_nid, to_nid); The result is that each CPU that was deconfigured at boot time stays in node 0 because cpu_to_node() returns the same node before and after setting the CPU online. Using "cpu->node_id" for "from_nid" instead of calling cpu_to_node() would help in our case. Signed-off-by: Michael Holzheu --- drivers/base/cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index f160ea4..2dd889c 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -47,7 +47,7 @@ static int __ref cpu_subsys_online(struct device *dev) int from_nid, to_nid; int ret; - from_nid = cpu_to_node(cpuid); + from_nid = cpu->node_id; if (from_nid == NUMA_NO_NODE) return -ENODEV; -- 2.3.8 -- 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/