From patchwork Mon Mar 15 16:34:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Garzarella X-Patchwork-Id: 12140029 X-Patchwork-Delegate: kuba@kernel.org 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=-16.0 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 507E4C433E6 for ; Mon, 15 Mar 2021 16:36:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A45D64F37 for ; Mon, 15 Mar 2021 16:36:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233079AbhCOQfw (ORCPT ); Mon, 15 Mar 2021 12:35:52 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:45360 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233058AbhCOQfn (ORCPT ); Mon, 15 Mar 2021 12:35:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615826143; 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=yS6yhrkWA8GbBenFIxogYtiFYE6uOSKcO/K046TS5vQ=; b=hZD0Raid7MnbkzoHdKTUIKrUdn8KLH3AtolxUEoZIM8kkLPKGMN73VydZQO5ze/fQHX+tc VO6YsN6vLFHUkMvRdwSHH1EfeBsG4mrtipmuuB2tXmeldXWIGA1C/lIIA6gdhPnQP9go1q eiy7Pdjo8yiKpf0Uy9k81H2CHwpQBJk= 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-356-3PfeEznlOUi2AgTM_nG-EA-1; Mon, 15 Mar 2021 12:35:39 -0400 X-MC-Unique: 3PfeEznlOUi2AgTM_nG-EA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A0B5C800C78; Mon, 15 Mar 2021 16:35:37 +0000 (UTC) Received: from steredhat.redhat.com (ovpn-114-1.ams2.redhat.com [10.36.114.1]) by smtp.corp.redhat.com (Postfix) with ESMTP id 376F72C169; Mon, 15 Mar 2021 16:35:29 +0000 (UTC) From: Stefano Garzarella To: virtualization@lists.linux-foundation.org Cc: netdev@vger.kernel.org, Xie Yongji , Laurent Vivier , Stefan Hajnoczi , linux-kernel@vger.kernel.org, Max Gurtovoy , Jason Wang , Parav Pandit , "Michael S. Tsirkin" , kvm@vger.kernel.org Subject: [PATCH v4 04/14] vringh: explain more about cleaning riov and wiov Date: Mon, 15 Mar 2021 17:34:40 +0100 Message-Id: <20210315163450.254396-5-sgarzare@redhat.com> In-Reply-To: <20210315163450.254396-1-sgarzare@redhat.com> References: <20210315163450.254396-1-sgarzare@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: netdev@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. Acked-by: Jason Wang Signed-off-by: Stefano Garzarella --- 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,