Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760669Ab1D1P1L (ORCPT ); Thu, 28 Apr 2011 11:27:11 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:41263 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755156Ab1D1P1I (ORCPT ); Thu, 28 Apr 2011 11:27:08 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: LKML , Andrew Morton Subject: [PATCH v2] cpumask: add cpumask_var_t documentation Cc: kosaki.motohiro@jp.fujitsu.com Message-Id: <20110429002847.3D77.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.56.05 [ja] Date: Fri, 29 Apr 2011 00:27:06 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1378 Lines: 43 cpumask_var_t has one nortable difference against cpumask_t. This patch adds the explanation. Signed-off-by: KOSAKI Motohiro --- include/linux/cpumask.h | 14 ++++++++++++++ 1 files changed, 14 insertions(+), 0 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index 1e40dd0..471c98a 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -617,6 +617,20 @@ static inline size_t cpumask_size(void) * ... use 'tmpmask' like a normal struct cpumask * ... * * free_cpumask_var(tmpmask); + * + * + * However, one notable exception is there. cpumask_var_t is allocated + * only nr_cpu_ids bits (in the other hand, real cpumask_t always has + * NR_CPUS bits). therefore You don't have to dereference cpumask_var_t. + * + * cpumask_var_t tmpmask; + * if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) + * return -ENOMEM; + * + * var = *tmpmask; + * + * This code makes NR_CPUS length memcopy and bring memroy corruption. + * You have to use cpumask_copy() instead. */ #ifdef CONFIG_CPUMASK_OFFSTACK typedef struct cpumask *cpumask_var_t; -- 1.7.3.1 -- 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/