From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753196AbdHNLus (ORCPT ); Mon, 14 Aug 2017 07:50:48 -0400 Received: from terminus.zytor.com ([65.50.211.136]:34071 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752823AbdHNLuq (ORCPT ); Mon, 14 Aug 2017 07:50:46 -0400 Date: Mon, 14 Aug 2017 04:46:06 -0700 From: tip-bot for Byungchul Park Message-ID: Cc: hpa@zytor.com, byungchul.park@lge.com, peterz@infradead.org, boqun.feng@gmail.com, torvalds@linux-foundation.org, mingo@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org Reply-To: peterz@infradead.org, byungchul.park@lge.com, boqun.feng@gmail.com, hpa@zytor.com, torvalds@linux-foundation.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, mingo@kernel.org In-Reply-To: <1502694052-16085-3-git-send-email-byungchul.park@lge.com> References: <1502694052-16085-3-git-send-email-byungchul.park@lge.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease Git-Commit-ID: 907dc16d7e23ec81a126c9585435494fa1b3a4b7 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 907dc16d7e23ec81a126c9585435494fa1b3a4b7 Gitweb: http://git.kernel.org/tip/907dc16d7e23ec81a126c9585435494fa1b3a4b7 Author: Byungchul Park AuthorDate: Mon, 14 Aug 2017 16:00:52 +0900 Committer: Ingo Molnar CommitDate: Mon, 14 Aug 2017 12:52:17 +0200 locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease As Boqun Feng pointed out, current->hist_id should be aligned with the latest valid xhlock->hist_id so that hist_id_save[] storing current->hist_id can be comparable with xhlock->hist_id. Fix it. Additionally, the condition for overwrite-detection should be the opposite. Fix the code and the comments as well. <- direction to visit hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh (h: history) ^^ ^ || start from here |previous entry current entry Reported-by: Boqun Feng Signed-off-by: Byungchul Park Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: akpm@linux-foundation.org Cc: kernel-team@lge.com Cc: kirill@shutemov.name Cc: linux-mm@kvack.org Cc: npiggin@gmail.com Cc: walken@google.com Cc: willy@infradead.org Link: http://lkml.kernel.org/r/1502694052-16085-3-git-send-email-byungchul.park@lge.com [ Improve the comments some more. ] Signed-off-by: Ingo Molnar --- kernel/locking/lockdep.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 257931e..66011c9 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -4853,7 +4853,7 @@ static void add_xhlock(struct held_lock *hlock) /* Initialize hist_lock's members */ xhlock->hlock = *hlock; - xhlock->hist_id = current->hist_id++; + xhlock->hist_id = ++current->hist_id; xhlock->trace.nr_entries = 0; xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES; @@ -5029,12 +5029,12 @@ static void commit_xhlocks(struct cross_lock *xlock) break; /* - * Filter out the cases that the ring buffer was - * overwritten and the previous entry has a bigger - * hist_id than the following one, which is impossible - * otherwise. + * Filter out the cases where the ring buffer was + * overwritten and the current entry has a bigger + * hist_id than the previous one, which is impossible + * otherwise: */ - if (unlikely(before(xhlock->hist_id, prev_hist_id))) + if (unlikely(before(prev_hist_id, xhlock->hist_id))) break; prev_hist_id = xhlock->hist_id;