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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 62C2DC43331 for ; Fri, 27 Mar 2020 22:26:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 392342073E for ; Fri, 27 Mar 2020 22:26:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585348009; bh=EC3QM1BbeU4Cs1HwMrmG+n0h5VnQjTcg8c5ioo+vBYk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=VvoP6pK4euKk0cNdvNPfNFZQo0Ua0153Xn450qK1ADc2/y+UTSOX1o4M4OvIVjHKL ddQBnzdQgXXyaHwqLAxIluSde/Dez75ENr7xL2ezyK81VPI0cnBSoC18shIZS1aqyK 0Ucmf5wgAV9Wlhx7hJ1cTH5C8tkImUOn0s95srmI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727725AbgC0WY7 (ORCPT ); Fri, 27 Mar 2020 18:24:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:42564 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727685AbgC0WY7 (ORCPT ); Fri, 27 Mar 2020 18:24:59 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D6B462076B; Fri, 27 Mar 2020 22:24:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585347899; bh=EC3QM1BbeU4Cs1HwMrmG+n0h5VnQjTcg8c5ioo+vBYk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IwmsQchjaT635fji9+oaxE6MEFjDgBK5K8ilcHgT17q2ceZf2egjAhkRjZ9SaWUvC qQHbWNrdHmbHWVw75Swcfk+hGB7+2nVxVxKRWTsK7bD57FsrAcVAK2ofWcm4VJV73/ 7kHKHZSlBS80OKISS4fghdNqPK2ltuOqp2A8sICQ= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.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, "Paul E. McKenney" Subject: [PATCH v3 tip/core/rcu 03/34] rcutorture: Add flag to produce non-busy-wait task stalls Date: Fri, 27 Mar 2020 15:24:25 -0700 Message-Id: <20200327222456.12470-3-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200327222346.GA12082@paulmck-ThinkPad-P72> References: <20200327222346.GA12082@paulmck-ThinkPad-P72> Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: "Paul E. McKenney" This commit aids testing of RCU task stall warning messages by adding an rcutorture.stall_cpu_block module parameter that results in the induced stall sleeping within the RCU read-side critical section. Spinning with interrupts disabled is still available via the rcutorture.stall_cpu_irqsoff module parameter, and specifying neither of these two module parameters will spin with preemption disabled. Note that sleeping (as opposed to preemption) results in additional complaints from RCU at context-switch time, so yet more testing. Signed-off-by: Paul E. McKenney --- Documentation/admin-guide/kernel-parameters.txt | 5 +++++ kernel/rcu/rcutorture.c | 15 +++++++++------ 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 1a5ff11..df2baf9 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4165,6 +4165,11 @@ Duration of CPU stall (s) to test RCU CPU stall warnings, zero to disable. + rcutorture.stall_cpu_block= [KNL] + Sleep while stalling if set. This will result + in warnings from preemptible RCU in addition + to any other stall-related activity. + rcutorture.stall_cpu_holdoff= [KNL] Time to wait (s) after boot before inducing stall. diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index b3301f3..ada5b91 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -102,6 +102,7 @@ torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable."); torture_param(int, stall_cpu_holdoff, 10, "Time to wait before starting stall (s)."); torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling."); +torture_param(int, stall_cpu_block, 0, "Sleep while stalling."); torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s"); torture_param(int, stutter, 5, "Number of seconds to run/halt test"); @@ -1599,6 +1600,7 @@ static int rcutorture_booster_init(unsigned int cpu) */ static int rcu_torture_stall(void *args) { + int idx; unsigned long stop_at; VERBOSE_TOROUT_STRING("rcu_torture_stall task started"); @@ -1610,21 +1612,22 @@ static int rcu_torture_stall(void *args) if (!kthread_should_stop()) { stop_at = ktime_get_seconds() + stall_cpu; /* RCU CPU stall is expected behavior in following code. */ - rcu_read_lock(); + idx = cur_ops->readlock(); if (stall_cpu_irqsoff) local_irq_disable(); - else + else if (!stall_cpu_block) preempt_disable(); pr_alert("rcu_torture_stall start on CPU %d.\n", - smp_processor_id()); + raw_smp_processor_id()); while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(), stop_at)) - continue; /* Induce RCU CPU stall warning. */ + if (stall_cpu_block) + schedule_timeout_uninterruptible(HZ); if (stall_cpu_irqsoff) local_irq_enable(); - else + else if (!stall_cpu_block) preempt_enable(); - rcu_read_unlock(); + cur_ops->readunlock(idx); pr_alert("rcu_torture_stall end.\n"); } torture_shutdown_absorb("rcu_torture_stall"); -- 2.9.5