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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 D71FEC433E2 for ; Tue, 15 Sep 2020 20:09:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B8E620B1F for ; Tue, 15 Sep 2020 20:09:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="ULokTAlo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727977AbgIOUJ1 (ORCPT ); Tue, 15 Sep 2020 16:09:27 -0400 Received: from mail.efficios.com ([167.114.26.124]:59662 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727952AbgIOUIh (ORCPT ); Tue, 15 Sep 2020 16:08:37 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id B106C29E6BB; Tue, 15 Sep 2020 16:08:28 -0400 (EDT) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id Ys0kA5UKFAJc; Tue, 15 Sep 2020 16:08:28 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 7B90C29E6BA; Tue, 15 Sep 2020 16:08:28 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 7B90C29E6BA DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1600200508; bh=uRifFxx51fDjZwszuX1Hpmeb9WoFn46VpGDQuzPBtu4=; h=Date:From:To:Message-ID:MIME-Version; b=ULokTAloE4GdFgQV9FI1gNPYXT5NiKJTpwznGHIY/2zwq0vqtA4BK2JxT3ZbRTVQ9 RFPAPwsSyUWLnucmjPk9Vs2pTIPursb3vHxCdZDza+BQf3y+TTWaumkmbXcb+8pdhq nq4YqG/0WyGi1d3G0+vK0ps7WwGGmTSZl60paO5E/ebL7myKPIzK9CxyFA577T5rmC aQtxCZa1QDrFNNxT0nXMSY+aed+n0eFgZ2bpGh8LAKFFtCfAT5IU5FMux8tEqoBQtX SkNr/ZMAWe9/Vl+Ua+0KGAm19cUapVNOeppAx3yHsAp9ialchDfkksNZO9xKMSQQfg Qp8YlbMzAqdmg== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id w_V4XZgNHwiU; Tue, 15 Sep 2020 16:08:28 -0400 (EDT) Received: from mail03.efficios.com (mail03.efficios.com [167.114.26.124]) by mail.efficios.com (Postfix) with ESMTP id 6D50A29E65F; Tue, 15 Sep 2020 16:08:28 -0400 (EDT) Date: Tue, 15 Sep 2020 16:08:28 -0400 (EDT) From: Mathieu Desnoyers To: Peter Oskolkov Cc: paulmck , Peter Zijlstra , Boqun Feng , linux-kernel , Paul Turner , Chris Kennelly , Peter Oskolkov Message-ID: <1703212153.12161.1600200508335.JavaMail.zimbra@efficios.com> In-Reply-To: <20200915185541.1565837-1-posk@google.com> References: <20200915185541.1565837-1-posk@google.com> Subject: Re: [PATCH 1/2 v7] rseq/membarrier: add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.26.124] X-Mailer: Zimbra 8.8.15_GA_3965 (ZimbraWebClient - FF80 (Linux)/8.8.15_GA_3963) Thread-Topic: rseq/membarrier: add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ Thread-Index: 6fJXaDeXdPkbeXecg7bBmG22vozGug== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Sep 15, 2020, at 2:55 PM, Peter Oskolkov posk@google.com wrote: [...] > > -static int membarrier_private_expedited(int flags) > +static int membarrier_private_expedited(int flags, int cpu_id) > { > - int cpu; > cpumask_var_t tmpmask; > struct mm_struct *mm = current->mm; > + smp_call_func_t ipi_func = ipi_mb; > > - if (flags & MEMBARRIER_FLAG_SYNC_CORE) { > + if (flags == MEMBARRIER_FLAG_SYNC_CORE) { > if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) > return -EINVAL; > if (!(atomic_read(&mm->membarrier_state) & > MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY)) > return -EPERM; > + } else if (flags == MEMBARRIER_FLAG_RSEQ) { > + if (!IS_ENABLED(CONFIG_RSEQ)) > + return -EINVAL; > + if (!(atomic_read(&mm->membarrier_state) & > + MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY)) > + return -EPERM; > + ipi_func = ipi_rseq; > } else { > + BUG_ON(flags != 0); Usually BUG_ON() is really for utterly unrecoverable situations, which is not the case here. I am tempted to just use WARN_ON_ONCE(flags) instead to make dmesg yell (once) if an unexpected flags parameter is received. This is not a user-space input, so it should never trigger unless we change the code. The rest looks good to me, thanks! Reviewed-by: Mathieu Desnoyers Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com