| Message ID | 20210128144127.113245-5-sgarzare@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vdpa: add vdpa simulator for block device | expand |
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; > }
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; >> } >
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; }
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(). 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(-)