From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756759AbYHALIy (ORCPT ); Fri, 1 Aug 2008 07:08:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753265AbYHALIq (ORCPT ); Fri, 1 Aug 2008 07:08:46 -0400 Received: from viefep31-int.chello.at ([62.179.121.49]:63973 "EHLO viefep31-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753025AbYHALIp (ORCPT ); Fri, 1 Aug 2008 07:08:45 -0400 Subject: [PATCH] lockdep: lock_set_subclass - reset a held lock's subclass From: Peter Zijlstra To: David Miller Cc: mingo@elte.hu, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org In-Reply-To: <20080801.021348.233313767.davem@davemloft.net> References: <20080731.155504.167792984.davem@davemloft.net> <20080801.011122.32782916.davem@davemloft.net> <20080801090100.GA25142@elte.hu> <20080801.021348.233313767.davem@davemloft.net> Content-Type: text/plain Date: Fri, 01 Aug 2008 13:08:40 +0200 Message-Id: <1217588920.9686.6.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra Subject: lockdep: lock_set_subclass - reset a held lock's subclass this can be used to reset a held lock's subclass, for arbitrary-depth iterated data structures such as trees or lists which have per-node locks. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- include/linux/lockdep.h | 4 ++ kernel/lockdep.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 73 insertions(+) Index: linux-2.6/include/linux/lockdep.h =================================================================== --- linux-2.6.orig/include/linux/lockdep.h +++ linux-2.6/include/linux/lockdep.h @@ -300,6 +300,9 @@ extern void lock_acquire(struct lockdep_ extern void lock_release(struct lockdep_map *lock, int nested, unsigned long ip); +extern void lock_set_subclass(struct lockdep_map *lock, unsigned int subclass, + unsigned long ip); + # define INIT_LOCKDEP .lockdep_recursion = 0, #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0) @@ -316,6 +319,7 @@ static inline void lockdep_on(void) # define lock_acquire(l, s, t, r, c, i) do { } while (0) # define lock_release(l, n, i) do { } while (0) +# define lock_set_subclass(l, s, i) do { } while (0) # define lockdep_init() do { } while (0) # define lockdep_info() do { } while (0) # define lockdep_init_map(lock, name, key, sub) do { (void)(key); } while (0) Index: linux-2.6/kernel/lockdep.c =================================================================== --- linux-2.6.orig/kernel/lockdep.c +++ linux-2.6/kernel/lockdep.c @@ -2658,6 +2658,55 @@ static int check_unlock(struct task_stru return 1; } +static int +__lock_set_subclass(struct lockdep_map *lock, + unsigned int subclass, unsigned long ip) +{ + struct task_struct *curr = current; + struct held_lock *hlock, *prev_hlock; + struct lock_class *class; + unsigned int depth; + int i; + + depth = curr->lockdep_depth; + if (DEBUG_LOCKS_WARN_ON(!depth)) + return 0; + + prev_hlock = NULL; + for (i = depth-1; i >= 0; i--) { + hlock = curr->held_locks + i; + /* + * We must not cross into another context: + */ + if (prev_hlock && prev_hlock->irq_context != hlock->irq_context) + break; + if (hlock->instance == lock) + goto found_it; + prev_hlock = hlock; + } + return print_unlock_inbalance_bug(curr, lock, ip); + +found_it: + class = register_lock_class(lock, subclass, 0); + hlock->class = class; + + curr->lockdep_depth = i; + curr->curr_chain_key = hlock->prev_chain_key; + + for (; i < depth; i++) { + hlock = curr->held_locks + i; + if (!__lock_acquire(hlock->instance, + hlock->class->subclass, hlock->trylock, + hlock->read, hlock->check, hlock->hardirqs_off, + hlock->acquire_ip)) + return 0; + } + + if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) + return 0; + return 1; +} + /* * Remove the lock to the list of currently held locks in a * potentially non-nested (out of order) manner. This is a @@ -2822,6 +2871,26 @@ static void check_flags(unsigned long fl #endif } +void +lock_set_subclass(struct lockdep_map *lock, + unsigned int subclass, unsigned long ip) +{ + unsigned long flags; + + if (unlikely(current->lockdep_recursion)) + return; + + raw_local_irq_save(flags); + current->lockdep_recursion = 1; + check_flags(flags); + if (__lock_set_subclass(lock, subclass, ip)) + check_chain_key(current); + current->lockdep_recursion = 0; + raw_local_irq_restore(flags); +} + +EXPORT_SYMBOL_GPL(lock_set_subclass); + /* * We are not always called with irqs disabled - do that here, * and also avoid lockdep recursion: