From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88E71C388F2 for ; Fri, 6 Nov 2020 07:18:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D7A720936 for ; Fri, 6 Nov 2020 07:18:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726419AbgKFHSk (ORCPT ); Fri, 6 Nov 2020 02:18:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:45598 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725830AbgKFHSk (ORCPT ); Fri, 6 Nov 2020 02:18:40 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C69A8AB8F; Fri, 6 Nov 2020 07:18:38 +0000 (UTC) Date: Thu, 5 Nov 2020 22:56:42 -0800 From: Davidlohr Bueso To: paulmck@kernel.org Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org Subject: Re: [PATCH tip/core/rcu 03/28] locktorture: Track time of last ->writeunlock() Message-ID: <20201106065642.ti7mgrll7mbrndja@linux-p48b.lan> References: <20201105234658.GA23142@paulmck-ThinkPad-P72> <20201105234719.23307-3-paulmck@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20201105234719.23307-3-paulmck@kernel.org> User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 05 Nov 2020, paulmck@kernel.org wrote: >From: "Paul E. McKenney" > >This commit adds a last_lock_release variable that tracks the time of >the last ->writeunlock() call, which allows easier diagnosing of lock >hangs when using a kernel debugger. This makes sense to have. Acked-by: Davidlohr Bueso > >Cc: Davidlohr Bueso >Signed-off-by: Paul E. McKenney >--- > kernel/locking/locktorture.c | 2 ++ > 1 file changed, 2 insertions(+) > >diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c >index 62d215b..316531d 100644 >--- a/kernel/locking/locktorture.c >+++ b/kernel/locking/locktorture.c >@@ -60,6 +60,7 @@ static struct task_struct **reader_tasks; > > static bool lock_is_write_held; > static bool lock_is_read_held; >+static unsigned long last_lock_release; > > struct lock_stress_stats { > long n_lock_fail; >@@ -632,6 +633,7 @@ static int lock_torture_writer(void *arg) > lwsp->n_lock_acquired++; > cxt.cur_ops->write_delay(&rand); > lock_is_write_held = false; >+ WRITE_ONCE(last_lock_release, jiffies); > cxt.cur_ops->writeunlock(); > > stutter_wait("lock_torture_writer"); >-- >2.9.5 >