Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752249AbdHGHOn (ORCPT ); Mon, 7 Aug 2017 03:14:43 -0400 Received: from LGEAMRELO11.lge.com ([156.147.23.51]:36912 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752060AbdHGHOO (ORCPT ); Mon, 7 Aug 2017 03:14:14 -0400 X-Original-SENDERIP: 156.147.1.126 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com From: Byungchul Park To: peterz@infradead.org, mingo@kernel.org Cc: tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org, npiggin@gmail.com, kernel-team@lge.com Subject: [PATCH v8 04/14] lockdep: Make check_prev_add() able to handle external stack_trace Date: Mon, 7 Aug 2017 16:12:51 +0900 Message-Id: <1502089981-21272-5-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1502089981-21272-1-git-send-email-byungchul.park@lge.com> References: <1502089981-21272-1-git-send-email-byungchul.park@lge.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3591 Lines: 115 Currently, a space for stack_trace is pinned in check_prev_add(), that makes us not able to use external stack_trace. The simplest way to achieve it is to pass an external stack_trace as an argument. A more suitable solution is to pass a callback additionally along with a stack_trace so that callers can decide the way to save or whether to save. Actually crossrelease needs to do other than saving a stack_trace. So pass a stack_trace and callback to handle it, to check_prev_add(). Signed-off-by: Byungchul Park --- kernel/locking/lockdep.c | 40 +++++++++++++++++++--------------------- 1 file changed, 19 insertions(+), 21 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index b23e930..22a13f9 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1813,20 +1813,13 @@ static inline void inc_chains(void) */ static int check_prev_add(struct task_struct *curr, struct held_lock *prev, - struct held_lock *next, int distance, int *stack_saved) + struct held_lock *next, int distance, struct stack_trace *trace, + int (*save)(struct stack_trace *trace)) { struct lock_list *entry; int ret; struct lock_list this; struct lock_list *uninitialized_var(target_entry); - /* - * Static variable, serialized by the graph_lock(). - * - * We use this static variable to save the stack trace in case - * we call into this function multiple times due to encountering - * trylocks in the held lock stack. - */ - static struct stack_trace trace; /* * Prove that the new -> dependency would not @@ -1874,11 +1867,8 @@ static inline void inc_chains(void) } } - if (!*stack_saved) { - if (!save_trace(&trace)) - return 0; - *stack_saved = 1; - } + if (save && !save(trace)) + return 0; /* * Ok, all validations passed, add the new lock @@ -1886,14 +1876,14 @@ static inline void inc_chains(void) */ ret = add_lock_to_list(hlock_class(next), &hlock_class(prev)->locks_after, - next->acquire_ip, distance, &trace); + next->acquire_ip, distance, trace); if (!ret) return 0; ret = add_lock_to_list(hlock_class(prev), &hlock_class(next)->locks_before, - next->acquire_ip, distance, &trace); + next->acquire_ip, distance, trace); if (!ret) return 0; @@ -1901,8 +1891,6 @@ static inline void inc_chains(void) * Debugging printouts: */ if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) { - /* We drop graph lock, so another thread can overwrite trace. */ - *stack_saved = 0; graph_unlock(); printk("\n new dependency: "); print_lock_name(hlock_class(prev)); @@ -1926,8 +1914,9 @@ static inline void inc_chains(void) check_prevs_add(struct task_struct *curr, struct held_lock *next) { int depth = curr->lockdep_depth; - int stack_saved = 0; struct held_lock *hlock; + struct stack_trace trace; + int (*save)(struct stack_trace *trace) = save_trace; /* * Debugging checks. @@ -1952,9 +1941,18 @@ static inline void inc_chains(void) * added: */ if (hlock->read != 2 && hlock->check) { - if (!check_prev_add(curr, hlock, next, - distance, &stack_saved)) + int ret = check_prev_add(curr, hlock, next, + distance, &trace, save); + if (!ret) return 0; + + /* + * Stop saving stack_trace if save_trace() was + * called at least once: + */ + if (save && ret == 2) + save = NULL; + /* * Stop after the first non-trylock entry, * as non-trylock entries have added their -- 1.9.1