Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757543Ab0BLABM (ORCPT ); Thu, 11 Feb 2010 19:01:12 -0500 Received: from e1.ny.us.ibm.com ([32.97.182.141]:39379 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757409Ab0BLABG (ORCPT ); Thu, 11 Feb 2010 19:01:06 -0500 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, dvhltc@us.ibm.com, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 03/13] rcu: integrate rcu_dereference_check() message into lockdep Date: Thu, 11 Feb 2010 16:00:29 -0800 Message-Id: <1265932839-25899-3-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.6.6 In-Reply-To: <20100212000016.GA25781@linux.vnet.ibm.com> References: <20100212000016.GA25781@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2275 Lines: 72 Make rcu_dereference_check() print the list of held locks in addition to the stack dump to ease debugging. Signed-off-by: Paul E. McKenney --- include/linux/lockdep.h | 4 ++++ include/linux/rcupdate.h | 4 ++-- kernel/lockdep.c | 18 ++++++++++++++++++ 3 files changed, 24 insertions(+), 2 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 9ccf0e2..10206a8 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -534,4 +534,8 @@ do { \ # define might_lock_read(lock) do { } while (0) #endif +#ifdef CONFIG_PROVE_RCU +extern void lockdep_rcu_dereference(const char *file, const int line); +#endif + #endif /* __LINUX_LOCKDEP_H */ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 839d296..1a4de31 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -182,8 +182,8 @@ static inline int rcu_read_lock_sched_held(void) */ #define rcu_dereference_check(p, c) \ ({ \ - if (debug_locks) \ - WARN_ON_ONCE(!(c)); \ + if (debug_locks && !(c)) \ + lockdep_rcu_dereference(__FILE__, __LINE__); \ rcu_dereference_raw(p); \ }) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 5feaddc..a44c1b2 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3809,3 +3809,21 @@ void lockdep_sys_exit(void) lockdep_print_held_locks(curr); } } + +void lockdep_rcu_dereference(const char *file, const int line) +{ + struct task_struct *curr = current; + + if (!debug_locks_off()) + return; + printk("\n==============================================\n"); + printk( "[ BUG: Unsafe rcu_dereference_check() usage! ]\n"); + printk( "----------------------------------------------\n"); + printk("%s:%d invoked rcu_dereference_check() without protection!\n", + file, line); + printk("\nother info that might help us debug this:\n\n"); + lockdep_print_held_locks(curr); + printk("\nstack backtrace:\n"); + dump_stack(); +} +EXPORT_SYMBOL_GPL(lockdep_rcu_dereference); -- 1.6.6 -- 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/