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=-17.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 F08D3C433DB for ; Fri, 5 Feb 2021 03:20:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5F6164F92 for ; Fri, 5 Feb 2021 03:20:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230153AbhBEDUR (ORCPT ); Thu, 4 Feb 2021 22:20:17 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:42670 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229717AbhBEDUQ (ORCPT ); Thu, 4 Feb 2021 22:20:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612495129; 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=Z+OMUQChPI2nH7Skoc2akxJEI5HA3PfrfqiF984pQ/0=; b=LUrhnNXrmqYVdrA/QPswwFGQNCpYOV29XVZVtpDDUgXPFW/mdYVRkQUqLfc5uPDNPnsjXY 49eUtSUwTJX/OS+kbjz3Mukolvx5etCrERLBLHeq1/GLOJ4QOMsl2Y4h2f+moqmnodjjet dtw0KfathODlxVdJLO0VuYTpEj6UdWw= 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-584-Er2d2Fp0Pbuskmk1acdrAQ-1; Thu, 04 Feb 2021 22:18:47 -0500 X-MC-Unique: Er2d2Fp0Pbuskmk1acdrAQ-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 A3E421020C20; Fri, 5 Feb 2021 03:18:46 +0000 (UTC) Received: from [10.72.12.112] (ovpn-12-112.pek2.redhat.com [10.72.12.112]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4448D60BE2; Fri, 5 Feb 2021 03:18:37 +0000 (UTC) Subject: Re: [PATCH v3 04/13] vringh: explain more about cleaning riov and wiov To: Stefano Garzarella , virtualization@lists.linux-foundation.org Cc: Xie Yongji , kvm@vger.kernel.org, Laurent Vivier , Stefan Hajnoczi , Max Gurtovoy , linux-kernel@vger.kernel.org, "Michael S. Tsirkin" References: <20210204172230.85853-1-sgarzare@redhat.com> <20210204172230.85853-5-sgarzare@redhat.com> From: Jason Wang Message-ID: <4a4bf8ad-5853-c054-4d04-450f1966c9a2@redhat.com> Date: Fri, 5 Feb 2021 11:18:36 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210204172230.85853-5-sgarzare@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/2/5 上午1:22, Stefano Garzarella wrote: > riov and wiov can be reused with subsequent calls of vringh_getdesc_*(). > > Let's add a paragraph in the documentation of these functions to better > explain when riov and wiov need to be cleaned up. > > Signed-off-by: Stefano Garzarella > --- > drivers/vhost/vringh.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) Acked-by: Jason Wang > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > index bee63d68201a..2a88e087afd8 100644 > --- a/drivers/vhost/vringh.c > +++ b/drivers/vhost/vringh.c > @@ -662,7 +662,10 @@ EXPORT_SYMBOL(vringh_init_user); > * *head will be vrh->vring.num. You may be able to ignore an invalid > * descriptor, but there's not much you can do with an invalid ring. > * > - * Note that you may need to clean up riov and wiov, even on error! > + * Note that you can reuse riov and wiov with subsequent calls. Content is > + * overwritten and memory reallocated if more space is needed. > + * When you don't have to use riov and wiov anymore, you should clean up them > + * calling vringh_iov_cleanup() to release the memory, even on error! > */ > int vringh_getdesc_user(struct vringh *vrh, > struct vringh_iov *riov, > @@ -932,7 +935,10 @@ EXPORT_SYMBOL(vringh_init_kern); > * *head will be vrh->vring.num. You may be able to ignore an invalid > * descriptor, but there's not much you can do with an invalid ring. > * > - * Note that you may need to clean up riov and wiov, even on error! > + * Note that you can reuse riov and wiov with subsequent calls. Content is > + * overwritten and memory reallocated if more space is needed. > + * When you don't have to use riov and wiov anymore, you should clean up them > + * calling vringh_kiov_cleanup() to release the memory, even on error! > */ > int vringh_getdesc_kern(struct vringh *vrh, > struct vringh_kiov *riov, > @@ -1292,7 +1298,10 @@ EXPORT_SYMBOL(vringh_set_iotlb); > * *head will be vrh->vring.num. You may be able to ignore an invalid > * descriptor, but there's not much you can do with an invalid ring. > * > - * Note that you may need to clean up riov and wiov, even on error! > + * Note that you can reuse riov and wiov with subsequent calls. Content is > + * overwritten and memory reallocated if more space is needed. > + * When you don't have to use riov and wiov anymore, you should clean up them > + * calling vringh_kiov_cleanup() to release the memory, even on error! > */ > int vringh_getdesc_iotlb(struct vringh *vrh, > struct vringh_kiov *riov,