From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762989AbXGaUUI (ORCPT ); Tue, 31 Jul 2007 16:20:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756074AbXGaUT4 (ORCPT ); Tue, 31 Jul 2007 16:19:56 -0400 Received: from e35.co.us.ibm.com ([32.97.110.153]:46095 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758918AbXGaUTz (ORCPT ); Tue, 31 Jul 2007 16:19:55 -0400 From: Kevin Corry Organization: IBM To: linuxppc-dev@ozlabs.org, LKML Subject: [PATCH] PowerPC: Fix num_cpus calculation in smp_call_function_map() Date: Tue, 31 Jul 2007 15:19:46 -0500 User-Agent: KMail/1.9.5 Cc: Carl Love MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707311519.48359.kevcorry@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org [POWERPC]: Fix num_cpus calculation in smp_call_function_map(). In smp_call_function_map(), num_cpus is set to the number of online CPUs minus one. However, if the CPU mask does not include all CPUs (except the one we're running on), the routine will hang in the first while() loop until the 8 second timeout occurs. The num_cpus should be set to the number of CPUs specified in the mask passed into the routine, after we've made any modifications to the mask. With this change, we can also get rid of the call to cpus_empty() and avoid adding another pass through the bitmask. Signed-off-by: Kevin Corry Signed-off-by: Carl Love Index: linux-2.6.23-rc1/arch/powerpc/kernel/smp.c =================================================================== --- linux-2.6.23-rc1.orig/arch/powerpc/kernel/smp.c +++ linux-2.6.23-rc1/arch/powerpc/kernel/smp.c @@ -212,11 +212,6 @@ int smp_call_function_map(void (*func) ( atomic_set(&data.finished, 0); spin_lock(&call_lock); - /* Must grab online cpu count with preempt disabled, otherwise - * it can change. */ - num_cpus = num_online_cpus() - 1; - if (!num_cpus) - goto done; /* remove 'self' from the map */ if (cpu_isset(smp_processor_id(), map)) @@ -224,7 +219,9 @@ int smp_call_function_map(void (*func) ( /* sanity check the map, remove any non-online processors. */ cpus_and(map, map, cpu_online_map); - if (cpus_empty(map)) + + num_cpus = cpus_weight(map); + if (!num_cpus) goto done; call_data = &data;