From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755538Ab0AMK2n (ORCPT ); Wed, 13 Jan 2010 05:28:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755496Ab0AMK2l (ORCPT ); Wed, 13 Jan 2010 05:28:41 -0500 Received: from hera.kernel.org ([140.211.167.34]:58761 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755532Ab0AMK2j (ORCPT ); Wed, 13 Jan 2010 05:28:39 -0500 Date: Wed, 13 Jan 2010 10:27:58 GMT From: "tip-bot for Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <12626498423064-git-send-email-> References: <12626498423064-git-send-email-> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/rcu] rcu: Add debug check for too many rcu_read_unlock() Message-ID: Git-Commit-ID: cba8244a0f1c277b6b1e48ed6504fa434119e24d X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Wed, 13 Jan 2010 10:27:58 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: cba8244a0f1c277b6b1e48ed6504fa434119e24d Gitweb: http://git.kernel.org/tip/cba8244a0f1c277b6b1e48ed6504fa434119e24d Author: Paul E. McKenney AuthorDate: Mon, 4 Jan 2010 16:04:01 -0800 Committer: Ingo Molnar CommitDate: Wed, 13 Jan 2010 09:06:06 +0100 rcu: Add debug check for too many rcu_read_unlock() TREE_PREEMPT_RCU maintains an rcu_read_lock_nesting counter in the task structure, which happens to be a signed int. So this patch adds a check for this counter being negative at the end of __rcu_read_unlock(). This check is under CONFIG_PROVE_LOCKING, so can be thought of as being part of lockdep. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12626498423064-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcutree_plugin.h | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index f11ebd4..e77cdf3 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -304,6 +304,9 @@ void __rcu_read_unlock(void) if (--ACCESS_ONCE(t->rcu_read_lock_nesting) == 0 && unlikely(ACCESS_ONCE(t->rcu_read_unlock_special))) rcu_read_unlock_special(t); +#ifdef CONFIG_PROVE_LOCKING + WARN_ON_ONCE(ACCESS_ONCE(t->rcu_read_lock_nesting) < 0); +#endif /* #ifdef CONFIG_PROVE_LOCKING */ } EXPORT_SYMBOL_GPL(__rcu_read_unlock);