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=-8.6 required=3.0 tests=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_SANE_1 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 34DE2C54FCE for ; Mon, 23 Mar 2020 15:00:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0AD382080C for ; Mon, 23 Mar 2020 15:00:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584975643; bh=sOwqdzjNyDhqWaqPuKSrOiqTlX2z5cN/FIXJ3P/xkjI=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=u/E/l8u6mqlKlcB0mhRRBCmxFFNxW2BvfL1iD2d9itQ3/bkFKNHvAIIMSmGkWi4Uf vlC32thPJGvP6lIC21GTrdlNrK5fOlIdtDKQ3AfjHX/6XYVKWhdBkEaYv4i57QKB/b 9b9FGpF2kL6M53K4RpvPUV8YsndTxcmRThc5D7dM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727411AbgCWPAf (ORCPT ); Mon, 23 Mar 2020 11:00:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:53060 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727400AbgCWPAf (ORCPT ); Mon, 23 Mar 2020 11:00:35 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8E0182076A; Mon, 23 Mar 2020 15:00:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584975634; bh=sOwqdzjNyDhqWaqPuKSrOiqTlX2z5cN/FIXJ3P/xkjI=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=zCkspbRTmHUxF9l9kRPZQnxtYGdYi8+u6rRR3/9+G3jy+1Py13gdsJwR0GL7JDxJY DSpD2HdIdJvkPPQPC0zgJceBlBX5G9X0TWzOx+qjPICnwN5AmkaI4wgCQcYvkrDVkI xQOQ+kQyCeBEE5NPoHcjWNEc/LS2t4bjGP3+oOWY= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 5B36B35226C6; Mon, 23 Mar 2020 08:00:34 -0700 (PDT) Date: Mon, 23 Mar 2020 08:00:34 -0700 From: "Paul E. McKenney" To: Qais Yousef Cc: Thomas Gleixner , linux-kernel@vger.kernel.org, Helge Deller , Michael Ellerman , "David S. Miller" , Juergen Gross , Mark Rutland , Lorenzo Pieralisi , xen-devel@lists.xenproject.org, linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: Re: [PATCH v4 01/17] cpu: Add new {add,remove}_cpu() functions Message-ID: <20200323150034.GG3199@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200323135110.30522-1-qais.yousef@arm.com> <20200323135110.30522-2-qais.yousef@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200323135110.30522-2-qais.yousef@arm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Mon, Mar 23, 2020 at 01:50:54PM +0000, Qais Yousef wrote: > The new functions use device_{online,offline}() which are userspace > safe. > > This is in preparation to move cpu_{up, down} kernel users to use > a safer interface that is not racy with userspace. > > Suggested-by: "Paul E. McKenney" > Signed-off-by: Qais Yousef > CC: Thomas Gleixner > CC: "Paul E. McKenney" Reviewed-by: Paul E. McKenney > CC: Helge Deller > CC: Michael Ellerman > CC: "David S. Miller" > CC: Juergen Gross > CC: Mark Rutland > CC: Lorenzo Pieralisi > CC: xen-devel@lists.xenproject.org > CC: linux-parisc@vger.kernel.org > CC: sparclinux@vger.kernel.org > CC: linuxppc-dev@lists.ozlabs.org > CC: linux-arm-kernel@lists.infradead.org > CC: x86@kernel.org > CC: linux-kernel@vger.kernel.org > --- > include/linux/cpu.h | 2 ++ > kernel/cpu.c | 24 ++++++++++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index 1ca2baf817ed..cf8cf38dca43 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -89,6 +89,7 @@ extern ssize_t arch_cpu_release(const char *, size_t); > #ifdef CONFIG_SMP > extern bool cpuhp_tasks_frozen; > int cpu_up(unsigned int cpu); > +int add_cpu(unsigned int cpu); > void notify_cpu_starting(unsigned int cpu); > extern void cpu_maps_update_begin(void); > extern void cpu_maps_update_done(void); > @@ -118,6 +119,7 @@ extern void cpu_hotplug_disable(void); > extern void cpu_hotplug_enable(void); > void clear_tasks_mm_cpumask(int cpu); > int cpu_down(unsigned int cpu); > +int remove_cpu(unsigned int cpu); > > #else /* CONFIG_HOTPLUG_CPU */ > > diff --git a/kernel/cpu.c b/kernel/cpu.c > index 9c706af713fb..069802f7010f 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -1057,6 +1057,18 @@ int cpu_down(unsigned int cpu) > } > EXPORT_SYMBOL(cpu_down); > > +int remove_cpu(unsigned int cpu) > +{ > + int ret; > + > + lock_device_hotplug(); > + ret = device_offline(get_cpu_device(cpu)); > + unlock_device_hotplug(); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(remove_cpu); > + > #else > #define takedown_cpu NULL > #endif /*CONFIG_HOTPLUG_CPU*/ > @@ -1209,6 +1221,18 @@ int cpu_up(unsigned int cpu) > } > EXPORT_SYMBOL_GPL(cpu_up); > > +int add_cpu(unsigned int cpu) > +{ > + int ret; > + > + lock_device_hotplug(); > + ret = device_online(get_cpu_device(cpu)); > + unlock_device_hotplug(); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(add_cpu); > + > #ifdef CONFIG_PM_SLEEP_SMP > static cpumask_var_t frozen_cpus; > > -- > 2.17.1 >