From: Stefano Garzarella <sgarzare@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: virtualization@lists.linux-foundation.org,
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 11:23:20 +0100 [thread overview]
Message-ID: <20210201102320.rk77l2aus3ku4ezz@steredhat> (raw)
In-Reply-To: <78247eb0-8e6e-f2fa-a693-1b0f14db61dd@redhat.com>
On Mon, Feb 01, 2021 at 01:43:23PM +0800, Jason Wang wrote:
>
>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.
Yes I agree.
I've tried to do this, but it requires quite a bit of work to change
vringh, I'll put it on my todo list.
Thanks,
Stefano
>
>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 10:24 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
2021-02-01 10:23 ` Stefano Garzarella [this message]
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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