From patchwork Thu Feb 4 17:22:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Garzarella X-Patchwork-Id: 12068083 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=-16.1 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,SPF_HELO_NONE,SPF_PASS 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 BD782C4332D for ; Thu, 4 Feb 2021 17:46:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E11E64DF2 for ; Thu, 4 Feb 2021 17:46:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238430AbhBDRZW (ORCPT ); Thu, 4 Feb 2021 12:25:22 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:57119 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238487AbhBDRYq (ORCPT ); Thu, 4 Feb 2021 12:24:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612459400; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=g6wh1LMLhZTu6Il2A+W8xiD5xAyI/ci9mY9NolndzMM=; b=IkJVTg2b9Ba3hVbSIq5yvsmv6tIox2ai5btSOGFXokkjJwbA90+/fjCg3sYqxx7Bi7Lir2 uZoOla2ohyFK5oicqQvw/8mzhVe0vyio1z0LUJk/9cKVOLDk2tIbTEIZEgkOgaGudbiOkX S+raRPF8B2erzEFlEH/4LpsMckViS+U= 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-502-8SAnTcfHMPiFLLJRk6Pj2A-1; Thu, 04 Feb 2021 12:23:18 -0500 X-MC-Unique: 8SAnTcfHMPiFLLJRk6Pj2A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 00370801965; Thu, 4 Feb 2021 17:23:17 +0000 (UTC) Received: from steredhat.redhat.com (ovpn-113-213.ams2.redhat.com [10.36.113.213]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8F95060937; Thu, 4 Feb 2021 17:23:08 +0000 (UTC) From: Stefano Garzarella To: virtualization@lists.linux-foundation.org Cc: Stefano Garzarella , Xie Yongji , kvm@vger.kernel.org, Laurent Vivier , Stefan Hajnoczi , Max Gurtovoy , linux-kernel@vger.kernel.org, Jason Wang , "Michael S. Tsirkin" Subject: [PATCH v3 04/13] vringh: explain more about cleaning riov and wiov Date: Thu, 4 Feb 2021 18:22:21 +0100 Message-Id: <20210204172230.85853-5-sgarzare@redhat.com> In-Reply-To: <20210204172230.85853-1-sgarzare@redhat.com> References: <20210204172230.85853-1-sgarzare@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 Acked-by: Jason Wang --- drivers/vhost/vringh.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) 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,