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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,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 0644EC433E0 for ; Mon, 8 Mar 2021 16:05:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B26ED65210 for ; Mon, 8 Mar 2021 16:05:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230476AbhCHQEm (ORCPT ); Mon, 8 Mar 2021 11:04:42 -0500 Received: from smtp-fw-2101.amazon.com ([72.21.196.25]:51906 "EHLO smtp-fw-2101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230143AbhCHQEb (ORCPT ); Mon, 8 Mar 2021 11:04:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1615219471; x=1646755471; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=+AelMi3v18s6+/y1BQYDbI2IpSHlRy2T4ik8Uc3Ym70=; b=bG+4hnas4YNJk3w/HmOqvVeY0XcC9WLfWavRcwA2XepyTLkOrvzF0iai qatRTWUCuFwcmPL13liOMq6b3hZDBLKEn609oeBiZ4QUDZtAFZf1du0fh 3GZCBys2dLCTpJOKocAejwqKPfdsmp3hC7WO0ylPiEvILECqQyA1Y+oxh U=; X-IronPort-AV: E=Sophos;i="5.81,232,1610409600"; d="scan'208";a="92508455" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-1a-807d4a99.us-east-1.amazon.com) ([10.43.8.6]) by smtp-border-fw-out-2101.iad2.amazon.com with ESMTP; 08 Mar 2021 16:04:19 +0000 Received: from EX13MTAUWC002.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan2.iad.amazon.com [10.40.163.34]) by email-inbound-relay-1a-807d4a99.us-east-1.amazon.com (Postfix) with ESMTPS id 9E5F4A1F36; Mon, 8 Mar 2021 16:04:08 +0000 (UTC) Received: from EX13D20UWC001.ant.amazon.com (10.43.162.244) by EX13MTAUWC002.ant.amazon.com (10.43.162.240) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 8 Mar 2021 16:04:08 +0000 Received: from Alexanders-MacBook-Air.local (10.43.162.131) by EX13D20UWC001.ant.amazon.com (10.43.162.244) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 8 Mar 2021 16:04:00 +0000 Subject: Re: [PATCH v8] drivers/misc: sysgenid: add system generation id driver To: Greg KH , Adrian Catangiu CC: , , , , , , , , , <0x7f454c46@gmail.com>, , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <1615213083-29869-1-git-send-email-acatan@amazon.com> From: Alexander Graf Message-ID: Date: Mon, 8 Mar 2021 17:03:58 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Originating-IP: [10.43.162.131] X-ClientProxiedBy: EX13D19UWA003.ant.amazon.com (10.43.160.170) To EX13D20UWC001.ant.amazon.com (10.43.162.244) Content-Type: text/plain; charset="windows-1252"; format="flowed" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 08.03.21 15:36, Greg KH wrote: > = > On Mon, Mar 08, 2021 at 04:18:03PM +0200, Adrian Catangiu wrote: >> +static struct miscdevice sysgenid_misc =3D { >> + .minor =3D MISC_DYNAMIC_MINOR, >> + .name =3D "sysgenid", >> + .fops =3D &fops, >> +}; > = > Much cleaner, but: > = >> +static int __init sysgenid_init(void) >> +{ >> + int ret; >> + >> + sysgenid_data.map_buf =3D get_zeroed_page(GFP_KERNEL); >> + if (!sysgenid_data.map_buf) >> + return -ENOMEM; >> + >> + atomic_set(&sysgenid_data.generation_counter, 0); >> + atomic_set(&sysgenid_data.outdated_watchers, 0); >> + init_waitqueue_head(&sysgenid_data.read_waitq); >> + init_waitqueue_head(&sysgenid_data.outdated_waitq); >> + spin_lock_init(&sysgenid_data.lock); >> + >> + ret =3D misc_register(&sysgenid_misc); >> + if (ret < 0) { >> + pr_err("misc_register() failed for sysgenid\n"); >> + goto err; >> + } >> + >> + return 0; >> + >> +err: >> + free_pages(sysgenid_data.map_buf, 0); >> + sysgenid_data.map_buf =3D 0; >> + >> + return ret; >> +} >> + >> +static void __exit sysgenid_exit(void) >> +{ >> + misc_deregister(&sysgenid_misc); >> + free_pages(sysgenid_data.map_buf, 0); >> + sysgenid_data.map_buf =3D 0; >> +} >> + >> +module_init(sysgenid_init); >> +module_exit(sysgenid_exit); > = > So you do this for any bit of hardware that happens to be out there? > Will that really work? You do not have any hwid to trigger off of to > know that this is a valid device you can handle? The interface is already useful in a pure container context where the = generation change request is triggered by software. And yes, there are hardware triggers, but Michael was quite unhappy = about potential races between VMGenID change and SysGenID change and = thus wanted to ideally separate the interfaces. So we went ahead and = isolated the SysGenID one, as it's already useful as is. Hardware drivers to inject change events into SysGenID can then follow = later, for all different hardware platforms. But SysGenID as in this = patch is a completely hardware agnostic concept. Alex Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879