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=-20.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 2C6FAC6377B for ; Wed, 21 Jul 2021 21:04:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16C4D61363 for ; Wed, 21 Jul 2021 21:04:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229961AbhGUUYJ (ORCPT ); Wed, 21 Jul 2021 16:24:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:34738 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229682AbhGUUYH (ORCPT ); Wed, 21 Jul 2021 16:24:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 44F4661001; Wed, 21 Jul 2021 21:04:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626901483; bh=ObGy8V6cEg8aYBOyo0XPD2qmVdUjzVNCC1lAcCY6Kj8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lqRk3e34IDJ4YXIIKqeAospFRi8d8Om5g6BSAVWP5Ifu0TupQlG3jrWZwXYQ1jKfz 2dLSRrO7iEeY7MQreGCkLdtFeM3NRlBGy03iZu2fZsK3EwjW8VBbL+xeZLTXv1N+Xt 7zT03gUIUDiZnDhrDV8PeCHeh2FcAiBxixAXvzcP7MPptY9N6dWBRhiOItHbzhs4f2 5vcFUVTYAsBoaXFB7wNaOsxPaoKiI2Va48Tm121xCto0ZC8e28fZl/jXRlkELS2oaU E7S+skSgT4VlKnqHah7uOhYx/cw5LgYDRaNGLV6bB28C9Mh4Hg8rzBL2+dpdKBNNFH byN6iKsYr7nVQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 1D5285C0A03; Wed, 21 Jul 2021 14:04:43 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: 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, "Paul E. McKenney" Subject: [PATCH rcu 2/7] rcutorture: Preempt rather than block when testing task stalls Date: Wed, 21 Jul 2021 14:04:36 -0700 Message-Id: <20210721210441.796995-2-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210721210421.GA788053@paulmck-ThinkPad-P17-Gen-1> References: <20210721210421.GA788053@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Currently, rcu_torture_stall() does a one-jiffy timed wait when stall_cpu_block is set. This works, but emits a pointless splat in CONFIG_PREEMPT=y kernels. This commit avoids this splat by instead invoking preempt_schedule() in CONFIG_PREEMPT=y kernels. This uses an admittedly ugly #ifdef, but abstracted approaches just looked worse. A prettier approach would provide a preempt_schedule() definition with a WARN_ON() for CONFIG_PREEMPT=n kernels, but this seems quite silly. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcutorture.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 40ef5417d9545..ab4215266ebee 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -2022,8 +2022,13 @@ static int rcu_torture_stall(void *args) __func__, raw_smp_processor_id()); while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(), stop_at)) - if (stall_cpu_block) + if (stall_cpu_block) { +#ifdef CONFIG_PREEMPTION + preempt_schedule(); +#else schedule_timeout_uninterruptible(HZ); +#endif + } if (stall_cpu_irqsoff) local_irq_enable(); else if (!stall_cpu_block) -- 2.31.1.189.g2e36527f23