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 12DC8C433E6 for ; Mon, 31 Aug 2020 18:09:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC27B214D8 for ; Mon, 31 Aug 2020 18:09:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897360; bh=LmVslC1dU5CCoRMoEl6kiVj9HhpjeVhgru+RnSIzBRY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qxG++42jwFsnTYkeEMxfpTbqLvHnWns6QbY9tDylsIpF+/FPQi+fw1AgGqhBNktPB 1FkEg3uRfLLjaxi2U6PRrYe3th3ZD/KJ2MgJXPToQD3y8l2nKwnc9MZnihIy1drAQ5 p1uNNfaoZ2cmP8qKJvCSZiJPnKiZ7pvhuAYZttAE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729522AbgHaSJU (ORCPT ); Mon, 31 Aug 2020 14:09:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:55374 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729246AbgHaSHz (ORCPT ); Mon, 31 Aug 2020 14:07:55 -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 533D521527; Mon, 31 Aug 2020 18:07:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897273; bh=LmVslC1dU5CCoRMoEl6kiVj9HhpjeVhgru+RnSIzBRY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zzk+nlOXerMYMhcMLhxutunfy2aKWT/opTfzRgMWDAE2A1JliF6SsFhTasaoajT8f XkQWO56jABFEFb0JTlNPRzOgIYGeZBmqOm3xHal4whXgQchEaM6YhVRKCFlOmxpJJn 9B7c55XjOKNBQYRSNQFOwc9XpNCcxwxEEnrT5+sU= 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 08/19] scftorture: Add smp_call_function_many() memory-ordering checks Date: Mon, 31 Aug 2020 11:07:38 -0700 Message-Id: <20200831180749.843-8-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831180731.GA582@paulmck-ThinkPad-P72> References: <20200831180731.GA582@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 adds checks for memory misordering across calls to and returns from smp_call_function_many() in the case where the caller waits. Misordering results in a splat. Note that in contrast to smp_call_function_single(), this code does not test memory ordering into the handler in the no-wait case because none of the handlers would be able to free the scf_check structure without introducing heavy synchronization to work out which was last. [ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ] Signed-off-by: Paul E. McKenney --- kernel/scftorture.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/kernel/scftorture.c b/kernel/scftorture.c index 9b42271..3519ad1 100644 --- a/kernel/scftorture.c +++ b/kernel/scftorture.c @@ -240,8 +240,11 @@ static void scf_handler(void *scfc_in) unsigned long r = torture_random(this_cpu_ptr(&scf_torture_rand)); struct scf_check *scfcp = scfc_in; - if (likely(scfcp) && WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in)))) - atomic_inc(&n_mb_in_errs); + if (likely(scfcp)) { + WRITE_ONCE(scfcp->scfc_out, false); // For multiple receivers. + if (WARN_ON_ONCE(unlikely(!READ_ONCE(scfcp->scfc_in)))) + atomic_inc(&n_mb_in_errs); + } this_cpu_inc(scf_invoked_count); if (longwait <= 0) { if (!(r & 0xffc0)) @@ -325,11 +328,28 @@ static void scftorture_invoke_one(struct scf_statistics *scfp, struct torture_ra } break; case SCF_PRIM_MANY: + if (scfsp->scfs_wait) { + scfcp = kmalloc(sizeof(*scfcp), GFP_ATOMIC); + if (WARN_ON_ONCE(!scfcp)) + atomic_inc(&n_alloc_errs); + } if (scfsp->scfs_wait) scfp->n_many_wait++; else scfp->n_many++; - smp_call_function_many(cpu_online_mask, scf_handler, NULL, scfsp->scfs_wait); + if (scfcp) { + scfcp->scfc_cpu = -1; + scfcp->scfc_wait = true; + scfcp->scfc_out = false; + scfcp->scfc_in = true; + } + smp_call_function_many(cpu_online_mask, scf_handler, scfcp, scfsp->scfs_wait); + if (scfcp) { + if (WARN_ON_ONCE(!scfcp->scfc_out)) + atomic_inc(&n_mb_out_errs); // Leak rather than trash! + else + kfree(scfcp); + } break; case SCF_PRIM_ALL: if (scfsp->scfs_wait) -- 2.9.5