From owner-svn-src-all@freebsd.org Mon Oct 19 15:06:23 2015 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8648EA19F1B; Mon, 19 Oct 2015 15:06:23 +0000 (UTC) (envelope-from hps@selasky.org) Received: from mail.turbocat.net (heidi.turbocat.net [88.198.202.214]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4C7A761F; Mon, 19 Oct 2015 15:06:22 +0000 (UTC) (envelope-from hps@selasky.org) Received: from laptop015.home.selasky.org (cm-176.74.213.204.customer.telag.net [176.74.213.204]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.turbocat.net (Postfix) with ESMTPSA id BB5A81FE023; Mon, 19 Oct 2015 17:06:19 +0200 (CEST) Subject: Re: svn commit: r289565 - head/sys/ofed/include/linux To: Konstantin Belousov References: <201510191056.t9JAuWhF052021@repo.freebsd.org> <20151019150130.GK2257@kib.kiev.ua> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org From: Hans Petter Selasky Message-ID: <56250752.5030007@selasky.org> Date: Mon, 19 Oct 2015 17:08:02 +0200 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20151019150130.GK2257@kib.kiev.ua> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Oct 2015 15:06:23 -0000 On 10/19/15 17:01, Konstantin Belousov wrote: > On Mon, Oct 19, 2015 at 10:56:32AM +0000, Hans Petter Selasky wrote: >> Author: hselasky >> Date: Mon Oct 19 10:56:32 2015 >> New Revision: 289565 >> URL: https://svnweb.freebsd.org/changeset/base/289565 >> >> Log: >> Merge LinuxKPI changes from DragonflyBSD: >> - Implement pagefault_disable() and pagefault_enable(). >> >> Sponsored by: Mellanox Technologies >> >> Modified: >> head/sys/ofed/include/linux/uaccess.h >> >> Modified: head/sys/ofed/include/linux/uaccess.h >> ============================================================================== >> --- head/sys/ofed/include/linux/uaccess.h Mon Oct 19 10:54:24 2015 (r289564) >> +++ head/sys/ofed/include/linux/uaccess.h Mon Oct 19 10:56:32 2015 (r289565) >> @@ -2,7 +2,8 @@ >> * Copyright (c) 2010 Isilon Systems, Inc. >> * Copyright (c) 2010 iX Systems, Inc. >> * Copyright (c) 2010 Panasas, Inc. >> - * Copyright (c) 2013, 2014 Mellanox Technologies, Ltd. >> + * Copyright (c) 2013-2015 Mellanox Technologies, Ltd. >> + * Copyright (c) 2015 Fran??ois Tigeot >> * All rights reserved. >> * >> * Redistribution and use in source and binary forms, with or without >> @@ -32,4 +33,14 @@ >> #define get_user(_x, _p) -copyin((_p), &(_x), sizeof(*(_p))) >> #define put_user(_x, _p) -copyout(&(_x), (_p), sizeof(*(_p))) >> >> +static inline void pagefault_disable(void) >> +{ >> + curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR); >> +} >> + >> +static inline void pagefault_enable(void) >> +{ >> + curthread_pflags_restore(~(TDP_NOFAULTING | TDP_RESETSPUR)); >> +} >> + >> #endif /* _LINUX_UACCESS_H_ */ > > This is wrong on many counts. First, we already provide the wrappers to > implement the nofaulting behaviour, see vm_fault_disable_pagefaults() > and vm_fault_enable_pagefaults(). > > Second, your implementation ignores possible recursion on the > state, unconditionally re-enabling faulting, and more seriously, it > unconditionally obliterates the spurious faults tracker. > > The return value from vm_fault_disable_pagefaults() is there for the reason, > and if Linux KPI does not have a place to store the state, some replacement > must be implemented instead of silently corrupting the flags on enable. > Hi Konstantin, Thank you for you input. I'll update these functions according to your suggestion. We can have a return value, even if Linux doesn't. It doesn't have to be exactly the same and then I can set a compiler attribute that the return value must be checked. --HPS