From: Jason Wang <jasowang@redhat.com>
To: Stefano Garzarella <sgarzare@redhat.com>,
virtualization@lists.linux-foundation.org
Cc: Xie Yongji <xieyongji@bytedance.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Laurent Vivier <lvivier@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
linux-kernel@vger.kernel.org, Max Gurtovoy <mgurtovoy@nvidia.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH RFC v2 04/10] vringh: implement vringh_kiov_advance()
Date: Mon, 1 Feb 2021 13:43:23 +0800 [thread overview]
Message-ID: <78247eb0-8e6e-f2fa-a693-1b0f14db61dd@redhat.com> (raw)
In-Reply-To: <20210128144127.113245-5-sgarzare@redhat.com>
On 2021/1/28 下午10:41, Stefano Garzarella wrote:
> In some cases, it may be useful to provide a way to skip a number
> of bytes in a vringh_kiov.
>
> Let's implement vringh_kiov_advance() for this purpose, reusing the
> code from vringh_iov_xfer().
> We replace that code calling the new vringh_kiov_advance().
Acked-by: Jason Wang <jasowang@redhat.com>
In the long run we need to switch to use iov iterator library instead.
Thanks
>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
> include/linux/vringh.h | 2 ++
> drivers/vhost/vringh.c | 41 +++++++++++++++++++++++++++++------------
> 2 files changed, 31 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/vringh.h b/include/linux/vringh.h
> index 9c077863c8f6..755211ebd195 100644
> --- a/include/linux/vringh.h
> +++ b/include/linux/vringh.h
> @@ -199,6 +199,8 @@ static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
> kiov->iov = NULL;
> }
>
> +void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len);
> +
> int vringh_getdesc_kern(struct vringh *vrh,
> struct vringh_kiov *riov,
> struct vringh_kiov *wiov,
> diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> index bee63d68201a..4d800e4f31ca 100644
> --- a/drivers/vhost/vringh.c
> +++ b/drivers/vhost/vringh.c
> @@ -75,6 +75,34 @@ static inline int __vringh_get_head(const struct vringh *vrh,
> return head;
> }
>
> +/**
> + * vringh_kiov_advance - skip bytes from vring_kiov
> + * @iov: an iov passed to vringh_getdesc_*() (updated as we consume)
> + * @len: the maximum length to advance
> + */
> +void vringh_kiov_advance(struct vringh_kiov *iov, size_t len)
> +{
> + while (len && iov->i < iov->used) {
> + size_t partlen = min(iov->iov[iov->i].iov_len, len);
> +
> + iov->consumed += partlen;
> + iov->iov[iov->i].iov_len -= partlen;
> + iov->iov[iov->i].iov_base += partlen;
> +
> + if (!iov->iov[iov->i].iov_len) {
> + /* Fix up old iov element then increment. */
> + iov->iov[iov->i].iov_len = iov->consumed;
> + iov->iov[iov->i].iov_base -= iov->consumed;
> +
> + iov->consumed = 0;
> + iov->i++;
> + }
> +
> + len -= partlen;
> + }
> +}
> +EXPORT_SYMBOL(vringh_kiov_advance);
> +
> /* Copy some bytes to/from the iovec. Returns num copied. */
> static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
> struct vringh_kiov *iov,
> @@ -95,19 +123,8 @@ static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
> done += partlen;
> len -= partlen;
> ptr += partlen;
> - iov->consumed += partlen;
> - iov->iov[iov->i].iov_len -= partlen;
> - iov->iov[iov->i].iov_base += partlen;
>
> - if (!iov->iov[iov->i].iov_len) {
> - /* Fix up old iov element then increment. */
> - iov->iov[iov->i].iov_len = iov->consumed;
> - iov->iov[iov->i].iov_base -= iov->consumed;
> -
> -
> - iov->consumed = 0;
> - iov->i++;
> - }
> + vringh_kiov_advance(iov, partlen);
> }
> return done;
> }
next prev parent reply other threads:[~2021-02-01 5:49 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 14:41 [PATCH RFC v2 00/10] vdpa: add vdpa simulator for block device Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 01/10] vdpa_sim: use iova module to allocate IOVA addresses Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 02/10] vringh: add 'iotlb_lock' to synchronize iotlb accesses Stefano Garzarella
2021-01-29 7:43 ` Jason Wang
[not found] ` <20210129091850.gatf3ih3knw2p4l4@steredhat>
2021-02-01 6:31 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 03/10] vringh: reset kiov 'consumed' field in __vringh_iov() Stefano Garzarella
2021-02-01 5:40 ` Jason Wang
2021-02-01 10:21 ` Stefano Garzarella
2021-02-02 3:26 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 04/10] vringh: implement vringh_kiov_advance() Stefano Garzarella
2021-02-01 5:43 ` Jason Wang [this message]
2021-02-01 10:23 ` Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 05/10] vringh: add vringh_kiov_length() helper Stefano Garzarella
2021-02-01 5:46 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 06/10] vdpa_sim: cleanup kiovs in vdpasim_free() Stefano Garzarella
2021-02-01 5:47 ` Jason Wang
2021-01-28 14:41 ` [PATCH RFC v2 07/10] vdpa: Remove the restriction that only supports virtio-net devices Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 08/10] vdpa: add vdpa simulator for block device Stefano Garzarella
2021-01-31 15:31 ` Max Gurtovoy
2021-02-01 8:29 ` Stefano Garzarella
2021-02-01 5:50 ` Jason Wang
2021-02-02 9:34 ` Stefan Hajnoczi
2021-02-02 15:49 ` Stefano Garzarella
2021-02-03 16:45 ` Stefan Hajnoczi
2021-02-04 8:02 ` Stefano Garzarella
2021-01-28 14:41 ` [PATCH RFC v2 09/10] vdpa_sim_blk: implement ramdisk behaviour Stefano Garzarella
2021-02-01 6:03 ` Jason Wang
2021-02-02 9:41 ` Stefan Hajnoczi
2021-01-28 14:41 ` [PATCH RFC v2 10/10] vdpa_sim_blk: handle VIRTIO_BLK_T_GET_ID Stefano Garzarella
2021-02-01 6:04 ` Jason Wang
2021-02-02 9:44 ` Stefan Hajnoczi
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