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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 8BF1BC3B186 for ; Wed, 12 Feb 2020 07:55:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 62E45206DB for ; Wed, 12 Feb 2020 07:55:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="a65sjySZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728417AbgBLHzz (ORCPT ); Wed, 12 Feb 2020 02:55:55 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:55650 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728381AbgBLHzz (ORCPT ); Wed, 12 Feb 2020 02:55:55 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581494153; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6lJXyrbl6ehIPLDhdvGx94ceUYOxEq2wFztlRa5WwwQ=; b=a65sjySZfWE+uFTgwGTt3UWRH2xxIujiFDkmxzFSJzifUokUXoRzDODK7IaBqwxoOK76UU u8cMXcAaIkgK9l36CJ2VtsyIxobwpk604y5E8a6RpSshdS70UNGcE6nNGC09XClbOn5Lfy Fu50NaZfmgyrS6/7hZ8cn8V58eDW0FE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-320-Ai4LYDoyOY2q3q5g_r5Iww-1; Wed, 12 Feb 2020 02:55:51 -0500 X-MC-Unique: Ai4LYDoyOY2q3q5g_r5Iww-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5CB10107ACC9; Wed, 12 Feb 2020 07:55:49 +0000 (UTC) Received: from [10.72.13.111] (ovpn-13-111.pek2.redhat.com [10.72.13.111]) by smtp.corp.redhat.com (Postfix) with ESMTP id 29C5960BF1; Wed, 12 Feb 2020 07:55:32 +0000 (UTC) Subject: Re: [PATCH V2 3/5] vDPA: introduce vDPA bus To: Jason Gunthorpe Cc: mst@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, tiwei.bie@intel.com, maxime.coquelin@redhat.com, cunming.liang@intel.com, zhihong.wang@intel.com, rob.miller@broadcom.com, xiao.w.wang@intel.com, haotian.wang@sifive.com, lingshan.zhu@intel.com, eperezma@redhat.com, lulu@redhat.com, parav@mellanox.com, kevin.tian@intel.com, stefanha@redhat.com, rdunlap@infradead.org, hch@infradead.org, aadam@redhat.com, jiri@mellanox.com, shahafs@mellanox.com, hanand@xilinx.com, mhabets@solarflare.com References: <20200210035608.10002-1-jasowang@redhat.com> <20200210035608.10002-4-jasowang@redhat.com> <20200211134746.GI4271@mellanox.com> From: Jason Wang Message-ID: Date: Wed, 12 Feb 2020 15:55:31 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20200211134746.GI4271@mellanox.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/2/11 =E4=B8=8B=E5=8D=889:47, Jason Gunthorpe wrote: > On Mon, Feb 10, 2020 at 11:56:06AM +0800, Jason Wang wrote: >> +/** >> + * vdpa_register_device - register a vDPA device >> + * Callers must have a succeed call of vdpa_init_device() before. >> + * @vdev: the vdpa device to be registered to vDPA bus >> + * >> + * Returns an error when fail to add to vDPA bus >> + */ >> +int vdpa_register_device(struct vdpa_device *vdev) >> +{ >> + int err =3D device_add(&vdev->dev); >> + >> + if (err) { >> + put_device(&vdev->dev); >> + ida_simple_remove(&vdpa_index_ida, vdev->index); >> + } > This is a very dangerous construction, I've seen it lead to driver > bugs. Better to require the driver to always do the put_device on > error unwind Ok. > > The ida_simple_remove should probably be part of the class release > function to make everything work right It looks to me bus instead of class is the correct abstraction here=20 since the devices share a set of programming interface but not the=20 semantics. Or do you actually mean type here? > >> +/** >> + * vdpa_unregister_driver - unregister a vDPA device driver >> + * @drv: the vdpa device driver to be unregistered >> + */ >> +void vdpa_unregister_driver(struct vdpa_driver *drv) >> +{ >> + driver_unregister(&drv->driver); >> +} >> +EXPORT_SYMBOL_GPL(vdpa_unregister_driver); >> + >> +static int vdpa_init(void) >> +{ >> + if (bus_register(&vdpa_bus) !=3D 0) >> + panic("virtio bus registration failed"); >> + return 0; >> +} > Linus will tell you not to kill the kernel - return the error code and > propagate it up to the module init function. Yes, will fix. > >> +/** >> + * vDPA device - representation of a vDPA device >> + * @dev: underlying device >> + * @dma_dev: the actual device that is performing DMA >> + * @config: the configuration ops for this device. >> + * @index: device index >> + */ >> +struct vdpa_device { >> + struct device dev; >> + struct device *dma_dev; >> + const struct vdpa_config_ops *config; >> + int index; > unsigned values shuld be unsigned int > > Jason Will fix. Thanks >