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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 A1D6CC76192 for ; Tue, 16 Jul 2019 13:50:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 745422173E for ; Tue, 16 Jul 2019 13:50:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="apjGQC4h" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387708AbfGPNug (ORCPT ); Tue, 16 Jul 2019 09:50:36 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:45156 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726039AbfGPNue (ORCPT ); Tue, 16 Jul 2019 09:50:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=4QEK7Azm4CXxHXb645Kj2aMTlcOadurBJ2fe5B7TS1M=; b=apjGQC4hITTrWEdGA3ONfg2iP /828JlG4UXQWAPe6q3t5vInmtxm/ImNGOVeO2ciL/bHXTCCeJ3lo7PsY7/tBKn2UtrobfSixwiCtY kgRig9A7tfwzAxTlSkwecLEAcJR9Xy0kYhJwN/AwxaGDoTTD9TO1jtLYZgKDGjSi6VNEHRHXGOPeA wlIqIx04Ma33UX3iLA5MjsMbK5lhuPRBCTmaSuroDZSIwaRK2T/XM1hzHphFda9kJ2OgvcKwv/eSw lQDaavZxRRhg5Et/iYJrJzsYbR2BPvH0dKeeReBhTLPmIdxc8zBUqI1qSvv/RI3uot/wtEaj3PNuo +uLlOHQTg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hnNqO-0001Tb-K0; Tue, 16 Jul 2019 13:50:13 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6CD812059DEA3; Tue, 16 Jul 2019 15:50:10 +0200 (CEST) Date: Tue, 16 Jul 2019 15:50:10 +0200 From: Peter Zijlstra To: Herbert Xu Cc: Steffen Klassert , Daniel Jordan , andrea.parri@amarulasolutions.com, boqun.feng@gmail.com, paulmck@linux.ibm.com, linux-arch@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] padata: Use RCU when fetching pd from do_serial Message-ID: <20190716135010.GC3402@hirez.programming.kicks-ass.net> References: <20190712100636.mqdr567p7ozanlyl@gondor.apana.org.au> <20190712101012.GW14601@gauss3.secunet.de> <20190712160737.iniaaxlsnhs6azg5@ca-dmjordan1.us.oracle.com> <20190713050321.c5wq7a7jrb6q2pxn@gondor.apana.org.au> <20190715161045.zqwgsp62uqjnvx3l@ca-dmjordan1.us.oracle.com> <20190716100447.pdongriwwfxsuajf@gondor.apana.org.au> <20190716111410.GN17989@gauss3.secunet.de> <20190716125704.l2jolyyd3bue6hhn@gondor.apana.org.au> <20190716131520.GB3402@hirez.programming.kicks-ass.net> <20190716131807.twahbbdff6jhpnu2@gondor.apana.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190716131807.twahbbdff6jhpnu2@gondor.apana.org.au> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 16, 2019 at 09:18:07PM +0800, Herbert Xu wrote: > On Tue, Jul 16, 2019 at 03:15:20PM +0200, Peter Zijlstra wrote: > > > > > @@ -367,7 +368,7 @@ void padata_do_serial(struct padata_priv *padata) > > > struct parallel_data *pd; > > > int reorder_via_wq = 0; > > > > > > - pd = padata->pd; > > > + pd = rcu_dereference_bh(padata->inst->pd); > > > > > > cpu = get_cpu(); > > > > > > > That's weird for not having a matching assign and lacking comments to > > explain that. > > There is a matching rcu_assign_pointer. But we should add some > RCU markers. > > Or perhaps you're misreading the level of indirections :) Could well be, I'm not much familiar with this code; I'll look more careful.