From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755601Ab1IGG0I (ORCPT ); Wed, 7 Sep 2011 02:26:08 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:46550 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755736Ab1IGGVB (ORCPT ); Wed, 7 Sep 2011 02:21:01 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org, Michal Hocko , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 24/55] rcu: Not necessary to pass rcu_read_lock_held() to rcu_dereference_protected() Date: Tue, 6 Sep 2011 11:00:18 -0700 Message-Id: <1315332049-2604-24-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <20110906180015.GA2560@linux.vnet.ibm.com> References: <20110906180015.GA2560@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michal Hocko Since ca5ecddf (rcu: define __rcu address space modifier for sparse) rcu_dereference_check() use rcu_read_lock_held() as a part of condition automatically. Therefore, callers of rcu_dereference_check() no longer need to pass rcu_read_lock_held() to rcu_dereference_check(). Signed-off-by: Michal Hocko Signed-off-by: Paul E. McKenney --- Documentation/RCU/lockdep.txt | 10 ++++------ 1 files changed, 4 insertions(+), 6 deletions(-) diff --git a/Documentation/RCU/lockdep.txt b/Documentation/RCU/lockdep.txt index d7a49b2..4998c63 100644 --- a/Documentation/RCU/lockdep.txt +++ b/Documentation/RCU/lockdep.txt @@ -48,13 +48,11 @@ checking of rcu_dereference() primitives: value of the pointer itself, for example, against NULL. The rcu_dereference_check() check expression can be any boolean -expression, but would normally include one of the rcu_read_lock_held() -family of functions and a lockdep expression. However, any boolean -expression can be used. For a moderately ornate example, consider -the following: +expression, but would normally include a lockdep expression. However, +any boolean expression can be used. For a moderately ornate example, +consider the following: file = rcu_dereference_check(fdt->fd[fd], - rcu_read_lock_held() || lockdep_is_held(&files->file_lock) || atomic_read(&files->count) == 1); @@ -62,7 +60,7 @@ This expression picks up the pointer "fdt->fd[fd]" in an RCU-safe manner, and, if CONFIG_PROVE_RCU is configured, verifies that this expression is used in: -1. An RCU read-side critical section, or +1. An RCU read-side critical section (implicit), or 2. with files->file_lock held, or 3. on an unshared files_struct. -- 1.7.3.2