From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754455Ab1HGRzS (ORCPT ); Sun, 7 Aug 2011 13:55:18 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:39160 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754213Ab1HGRzO (ORCPT ); Sun, 7 Aug 2011 13:55:14 -0400 Date: Sun, 7 Aug 2011 18:55:11 +0100 From: Al Viro To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, David Howells Subject: fix rcu annotations noise in cred.h Message-ID: <20110807175511.GZ2203@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org task->cred is declared as __rcu, and access to other tasks' ->cred is, indeed, protected. Access to current->cred does not need rcu_dereference() at all, since only the task itself can change its ->cred. sparse, of course, has no way of knowing that... Add force-cast in current_cred(), make current_fsuid() et.al. use it. Signed-off-by: Al Viro --- diff --git a/include/linux/cred.h b/include/linux/cred.h index 48e82af..98f46ef 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -265,10 +265,11 @@ static inline void put_cred(const struct cred *_cred) /** * current_cred - Access the current task's subjective credentials * - * Access the subjective credentials of the current task. + * Access the subjective credentials of the current task. RCU-safe, + * since nobody else can modify it. */ #define current_cred() \ - (current->cred) + (*(__force struct cred **)¤t->cred) /** * __task_cred - Access a task's objective credentials @@ -307,7 +308,7 @@ static inline void put_cred(const struct cred *_cred) ({ \ struct user_struct *__u; \ struct cred *__cred; \ - __cred = (struct cred *) current_cred(); \ + __cred = current_cred(); \ __u = get_uid(__cred->user); \ __u; \ }) @@ -322,7 +323,7 @@ static inline void put_cred(const struct cred *_cred) ({ \ struct group_info *__groups; \ struct cred *__cred; \ - __cred = (struct cred *) current_cred(); \ + __cred = current_cred(); \ __groups = get_group_info(__cred->group_info); \ __groups; \ }) @@ -341,7 +342,7 @@ static inline void put_cred(const struct cred *_cred) #define current_cred_xxx(xxx) \ ({ \ - current->cred->xxx; \ + current_cred()->xxx; \ }) #define current_uid() (current_cred_xxx(uid))