From: Jason Wang <jasowang@redhat.com>
To: Stefano Garzarella <sgarzare@redhat.com>,
virtualization@lists.linux-foundation.org
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
Laurent Vivier <lvivier@redhat.com>,
linux-kernel@vger.kernel.org, Eli Cohen <elic@nvidia.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Max Gurtovoy <mgurtovoy@nvidia.com>
Subject: Re: [PATCH RFC 11/12] vringh: allow vringh_iov_xfer() to skip bytes when ptr is NULL
Date: Mon, 16 Nov 2020 12:32:02 +0800 [thread overview]
Message-ID: <a5cfe66f-5ae2-1a73-6010-74123721135b@redhat.com> (raw)
In-Reply-To: <20201113134712.69744-12-sgarzare@redhat.com>
On 2020/11/13 下午9:47, Stefano Garzarella wrote:
> In some cases, it may be useful to provide a way to skip a number
> of bytes in a vringh_iov.
>
> In order to keep vringh_iov consistent, let's reuse vringh_iov_xfer()
> logic and skip bytes when the ptr is NULL.
>
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>
> I'm not sure if this is the best option, maybe we can add a new
> function vringh_iov_skip().
>
> Suggestions?
I might be worth to check whether we can convert vringh_iov to use iov
iterator then we can use iov_iterator_advance() here.
Thanks
> ---
> drivers/vhost/vringh.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> index 8bd8b403f087..ed3290946ad7 100644
> --- a/drivers/vhost/vringh.c
> +++ b/drivers/vhost/vringh.c
> @@ -75,7 +75,9 @@ static inline int __vringh_get_head(const struct vringh *vrh,
> return head;
> }
>
> -/* Copy some bytes to/from the iovec. Returns num copied. */
> +/* Copy some bytes to/from the iovec. Returns num copied.
> + * If ptr is NULL, skips at most len bytes.
> + */
> static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
> struct vringh_kiov *iov,
> void *ptr, size_t len,
> @@ -89,12 +91,16 @@ static inline ssize_t vringh_iov_xfer(struct vringh *vrh,
> size_t partlen;
>
> partlen = min(iov->iov[iov->i].iov_len, len);
> - err = xfer(vrh, iov->iov[iov->i].iov_base, ptr, partlen);
> - if (err)
> - return err;
> +
> + if (ptr) {
> + err = xfer(vrh, iov->iov[iov->i].iov_base, ptr, partlen);
> + if (err)
> + return err;
> + ptr += partlen;
> + }
> +
> done += partlen;
> len -= partlen;
> - ptr += partlen;
> iov->consumed += partlen;
> iov->iov[iov->i].iov_len -= partlen;
> iov->iov[iov->i].iov_base += partlen;
next prev parent reply other threads:[~2020-11-16 4:32 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 13:47 [PATCH RFC 00/12] vdpa: generalize vdpa simulator and add block device Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 01/12] vhost-vdpa: add support for vDPA blk devices Stefano Garzarella
2020-11-17 10:57 ` Stefan Hajnoczi
2020-11-17 15:05 ` Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 02/12] vdpa: split vdpasim to core and net modules Stefano Garzarella
2020-11-16 4:00 ` Jason Wang
2020-11-16 9:39 ` Stefano Garzarella
2020-11-18 13:14 ` Stefano Garzarella
2020-11-19 6:16 ` Jason Wang
2020-11-13 13:47 ` [PATCH RFC 03/12] vdpa_sim: remove hard-coded virtq count Stefano Garzarella
2020-11-16 4:02 ` Jason Wang
2020-11-13 13:47 ` [PATCH RFC 04/12] vdpa: add vdpa simulator for block device Stefano Garzarella
2020-11-16 4:10 ` Jason Wang
2020-11-16 10:17 ` Stefano Garzarella
2020-11-17 11:11 ` Stefan Hajnoczi
2020-11-17 14:16 ` Stefano Garzarella
2020-11-17 16:43 ` Stefan Hajnoczi
2020-11-17 17:38 ` Stefano Garzarella
2020-11-18 11:23 ` Stefan Hajnoczi
2020-11-18 11:39 ` Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 05/12] vdpa_sim: remove the limit of IOTLB entries Stefano Garzarella
2020-11-16 4:12 ` Jason Wang
2020-11-16 10:22 ` Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 06/12] vdpa_sim: add struct vdpasim_device to store device properties Stefano Garzarella
2020-11-16 4:14 ` Jason Wang
2020-11-16 10:30 ` Stefano Garzarella
2020-11-17 11:23 ` Stefan Hajnoczi
2020-11-17 14:24 ` Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 07/12] vdpa_sim: move config management outside of the core Stefano Garzarella
2020-11-16 4:18 ` Jason Wang
2020-11-16 10:42 ` Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 08/12] vdpa_sim: use kvmalloc to allocate vdpasim->buffer Stefano Garzarella
2020-11-16 4:19 ` Jason Wang
2020-11-13 13:47 ` [PATCH RFC 09/12] vdpa_sim: make vdpasim->buffer size configurable Stefano Garzarella
2020-11-16 4:19 ` Jason Wang
2020-11-13 13:47 ` [PATCH RFC 10/12] vdpa_sim: split vdpasim_virtqueue's iov field in riov and wiov Stefano Garzarella
2020-11-16 4:21 ` Jason Wang
2020-11-17 11:27 ` Stefan Hajnoczi
2020-11-20 14:41 ` Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 11/12] vringh: allow vringh_iov_xfer() to skip bytes when ptr is NULL Stefano Garzarella
2020-11-16 4:32 ` Jason Wang [this message]
2020-11-16 11:48 ` Stefano Garzarella
2020-11-13 13:47 ` [PATCH RFC 12/12] vdpa_sim_blk: implement ramdisk behaviour Stefano Garzarella
2020-11-16 5:25 ` Jason Wang
2020-11-16 11:08 ` Stefano Garzarella
2020-11-16 9:50 ` Michael S. Tsirkin
2020-11-16 11:23 ` Stefano Garzarella
2020-11-17 11:36 ` Stefan Hajnoczi
2020-11-17 14:32 ` Stefano Garzarella
2020-11-16 3:37 ` [PATCH RFC 00/12] vdpa: generalize vdpa simulator and add block device Jason Wang
2020-11-16 8:53 ` Stefano Garzarella
2020-12-18 11:38 ` Stefano Garzarella
2020-12-21 3:16 ` Jason Wang
2020-12-21 11:14 ` Stefano Garzarella
2020-12-22 2:44 ` Jason Wang
2020-12-22 10:57 ` Stefano Garzarella
2020-12-22 12:29 ` Jason Wang
2020-12-22 12:56 ` Jason Wang
2020-12-22 13:23 ` Stefano Garzarella
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