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=-13.1 required=3.0 tests=BAYES_00,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 4E6E9C433E6 for ; Mon, 31 Aug 2020 18:01:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22F4520EDD for ; Mon, 31 Aug 2020 18:01:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598896912; bh=OV4rdtDJfndd8yIlNe+o4Ki+VpzlQTxASJjsVeMAmWQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=nzXvm8xkjgTe9dWwViqELPzY/Pl4DmnSDd6KV0T5avH+cG/n6Kc3FlwO/N3SlfQ3X I9B1+nHlrVr2QC42/Pxs/8zPqNnCIZTgLoZW2DDaXLRy2sMpG5m96y4mTTAkhhoXPV PiK5WXnaCP0YsFBlXVgX9G9I1gP9cjbuERwkCMdE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729058AbgHaSBt (ORCPT ); Mon, 31 Aug 2020 14:01:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:35926 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728772AbgHaSB0 (ORCPT ); Mon, 31 Aug 2020 14:01:26 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (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 7780C21707; Mon, 31 Aug 2020 18:01:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598896886; bh=OV4rdtDJfndd8yIlNe+o4Ki+VpzlQTxASJjsVeMAmWQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WBMhrXPqNrjbNozJLgrbF0I9Daiv9qPQCga4nI/foekBthdIzdIyliuhJM4c6nC74 k4EH+rrft/w1BsIlACxqq+Z2YsE4kZksM2aG40aLsYBh569NyPSLqL2KEkW7N7n1rb bssE3AD2+5BPYW3P6rHkT2kjtbM2xUAmOUqzJDUU= 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 tip/core/rcu 19/24] rcu/nocb: Add a warning for non-GP kthread running GP code Date: Mon, 31 Aug 2020 11:01:11 -0700 Message-Id: <20200831180116.32690-19-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831180050.GA32590@paulmck-ThinkPad-P72> References: <20200831180050.GA32590@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" This commit increases RCU's ability to defend itself by emitting a warning if one of the nocb CB kthreads invokes the GP kthread's wait function. This warning augments a similar check that is carried out at the end of rcutorture testing and when RCU CPU stall warnings are emitted. The problem with those checks is that the miscreants have long since departed and disposed of any and all evidence. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_plugin.h | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 4d63ee3..cb1e8c8 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1926,6 +1926,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp) * nearest grace period (if any) to wait for next. The CB kthreads * and the global grace-period kthread are awakened if needed. */ + WARN_ON_ONCE(my_rdp->nocb_gp_rdp != my_rdp); for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_cb_rdp) { trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check")); rcu_nocb_lock_irqsave(rdp, flags); -- 2.9.5