From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752338AbdIFIcX (ORCPT ); Wed, 6 Sep 2017 04:32:23 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:37754 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752261AbdIFIcS (ORCPT ); Wed, 6 Sep 2017 04:32:18 -0400 X-Google-Smtp-Source: ADKCNb4Dd+klr/zGe08jcs7gq8DXCMu7w1AgrM3n/zU6Y0Mv1OKqS7NM26y2rRbsh/NI9WEzFohMTA== From: Boqun Feng To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , Gautham R Shenoy , Byungchul Park , Boqun Feng Subject: [RFC tip/locking v2 07/13] lockdep: Support deadlock detection for recursive read in check_noncircular() Date: Wed, 6 Sep 2017 16:28:18 +0800 Message-Id: <20170906082824.16078-8-boqun.feng@gmail.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170906082824.16078-1-boqun.feng@gmail.com> References: <20170906082824.16078-1-boqun.feng@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, lockdep only has limit support for deadlock detection for recursive read locks. The basic idea of the detection is: Since we make __bfs() able to traverse only the strong dependency paths, so we report a circular deadlock if we could find a circle of a strong dependency path. Signed-off-by: Boqun Feng --- kernel/locking/lockdep.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index d9959f25247a..8a09b1a02342 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1345,6 +1345,14 @@ static inline int hlock_equal(struct lock_list *entry, void *data) (hlock->read == 2 || !entry->is_rr); } +static inline int hlock_conflict(struct lock_list *entry, void *data) +{ + struct held_lock *hlock = (struct held_lock *)data; + + return hlock_class(hlock) == entry->class && + (hlock->read != 2 || !entry->is_rr); +} + static noinline int print_circular_bug(struct lock_list *this, struct lock_list *target, struct held_lock *check_src, @@ -1459,18 +1467,18 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) } /* - * Prove that the dependency graph starting at can not + * Prove that the dependency graph starting at can not * lead to . Print an error and return BFS_RMATCH if it does. */ static noinline enum bfs_result -check_noncircular(struct lock_list *root, struct lock_class *target, +check_noncircular(struct lock_list *root, struct held_lock *target, struct lock_list **target_entry) { enum bfs_result result; debug_atomic_inc(nr_cyclic_checks); - result = __bfs_forwards(root, target, class_equal, target_entry); + result = __bfs_forwards(root, target, hlock_conflict, target_entry); return result; } -- 2.14.1