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=-2.2 required=3.0 tests=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 96241C76192 for ; Tue, 16 Jul 2019 11:14:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 766E32173B for ; Tue, 16 Jul 2019 11:14:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387578AbfGPLON (ORCPT ); Tue, 16 Jul 2019 07:14:13 -0400 Received: from a.mx.secunet.com ([62.96.220.36]:60600 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387553AbfGPLON (ORCPT ); Tue, 16 Jul 2019 07:14:13 -0400 Received: from localhost (localhost [127.0.0.1]) by a.mx.secunet.com (Postfix) with ESMTP id F314C201E1; Tue, 16 Jul 2019 13:14:11 +0200 (CEST) X-Virus-Scanned: by secunet Received: from a.mx.secunet.com ([127.0.0.1]) by localhost (a.mx.secunet.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id q2w7tSaGDtsl; Tue, 16 Jul 2019 13:14:10 +0200 (CEST) Received: from mail-essen-01.secunet.de (mail-essen-01.secunet.de [10.53.40.204]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by a.mx.secunet.com (Postfix) with ESMTPS id E0C74201D6; Tue, 16 Jul 2019 13:14:10 +0200 (CEST) Received: from gauss2.secunet.de (10.182.7.193) by mail-essen-01.secunet.de (10.53.40.204) with Microsoft SMTP Server id 14.3.439.0; Tue, 16 Jul 2019 13:14:11 +0200 Received: by gauss2.secunet.de (Postfix, from userid 1000) id 82D9C318040C; Tue, 16 Jul 2019 13:14:10 +0200 (CEST) Date: Tue, 16 Jul 2019 13:14:10 +0200 From: Steffen Klassert To: Herbert Xu CC: Daniel Jordan , , , , , , , Subject: Re: [PATCH] padata: use smp_mb in padata_reorder to avoid orphaned padata jobs Message-ID: <20190716111410.GN17989@gauss3.secunet.de> References: <20190711221205.29889-1-daniel.m.jordan@oracle.com> <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> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20190716100447.pdongriwwfxsuajf@gondor.apana.org.au> User-Agent: Mutt/1.9.4 (2018-02-28) X-EXCLAIMER-MD-CONFIG: 2c86f778-e09b-4440-8b15-867914633a10 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Tue, Jul 16, 2019 at 06:04:47PM +0800, Herbert Xu wrote: > On Mon, Jul 15, 2019 at 12:10:46PM -0400, Daniel Jordan wrote: > > > > I've been wrong before plenty of times, and there's nothing preventing this > > from being one of those times :) , but in this case I believe what I'm showing > > is correct. > > > > The padata_do_serial call for a given job ensures padata_reorder runs on the > > CPU that the job hashed to in padata_do_parallel, which is not necessarily the > > same CPU as the one that padata_do_parallel itself ran on. > > You're right. I was taking the comment in the code at face value, > never trust comments :) > > While looking at the code in question, I think it is seriously > broken. For instance, padata_replace does not deal with async > crypto at all. It would fail miserably if the underlying async > crypto held onto references to the old pd. Hm, yes looks like that. padata_replace should not call padata_free_pd() as long as the refcount is not zero. Currenlty padata_flush_queues() will BUG if there are references left. Maybe we can fix it if we call padata_free_pd() from padata_serial_worker() when it sent out the last object.