Messages in this thread | | | Subject | Re: [PATCH RFC v2 04/10] vringh: implement vringh_kiov_advance() | From | Jason Wang <> | Date | Mon, 1 Feb 2021 13:43:23 +0800 |
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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; > }
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