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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08C76C25B08 for ; Thu, 18 Aug 2022 03:09:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242794AbiHRDJ5 (ORCPT ); Wed, 17 Aug 2022 23:09:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239681AbiHRDJz (ORCPT ); Wed, 17 Aug 2022 23:09:55 -0400 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A958179601; Wed, 17 Aug 2022 20:09:53 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045176;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0VMYsNDR_1660792190; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VMYsNDR_1660792190) by smtp.aliyun-inc.com; Thu, 18 Aug 2022 11:09:51 +0800 Message-ID: <1660791937.681257-2-xuanzhuo@linux.alibaba.com> Subject: Re: [RFC v2 5/7] virtio: unmask F_NEXT flag in desc_extra Date: Thu, 18 Aug 2022 11:05:37 +0800 From: Xuan Zhuo To: Guo Zhi Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Guo Zhi , eperezma@redhat.com, jasowang@redhat.com, sgarzare@redhat.com, mst@redhat.com References: <20220817135718.2553-1-qtxuning1999@sjtu.edu.cn> <20220817135718.2553-6-qtxuning1999@sjtu.edu.cn> In-Reply-To: <20220817135718.2553-6-qtxuning1999@sjtu.edu.cn> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 17 Aug 2022 21:57:16 +0800, Guo Zhi wrote: > We didn't unmask F_NEXT flag in desc_extra in the end of a chain, > unmask it so that we can access desc_extra to get next information. I think we should state the purpose of this. > > Signed-off-by: Guo Zhi > --- > drivers/virtio/virtio_ring.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index a5ec724c01d8..1c1b3fa376a2 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -567,7 +567,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > } > /* Last one doesn't continue. */ > desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT); > - if (!indirect && vq->use_dma_api) > + if (!indirect) > vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &= > ~VRING_DESC_F_NEXT; > > @@ -584,6 +584,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq, > total_sg * sizeof(struct vring_desc), > VRING_DESC_F_INDIRECT, > false); > + vq->split.desc_extra[head & (vq->split.vring.num - 1)].flags &= > + ~VRING_DESC_F_NEXT; This seems unnecessary. > } > > /* We're using some buffers from the free list. */ > @@ -693,7 +695,7 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head, > /* Put back on free list: unmap first-level descriptors and find end */ > i = head; > > - while (vq->split.vring.desc[i].flags & nextflag) { > + while (vq->split.desc_extra[i].flags & nextflag) { nextflag is __virtio16 You can use VRING_DESC_F_NEXT directly. Thanks. > vring_unmap_one_split(vq, i); > i = vq->split.desc_extra[i].next; > vq->vq.num_free++; > -- > 2.17.1 >