Stefano Garzarella
2023-Sep-25 10:30 UTC
[PATCH] vringh: don't use vringh_kiov_advance() in vringh_iov_xfer()
In the while loop of vringh_iov_xfer(), `partlen` could be 0 if one of
the `iov` has 0 lenght.
In this case, we should skip the iov and go to the next one.
But calling vringh_kiov_advance() with 0 lenght does not cause the
advancement, since it returns immediately if asked to advance by 0 bytes.
Let's restore the code that was there before commit b8c06ad4d67d
("vringh: implement vringh_kiov_advance()"), avoiding using
vringh_kiov_advance().
Fixes: b8c06ad4d67d ("vringh: implement vringh_kiov_advance()")
Cc: stable at vger.kernel.org
Reported-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare at redhat.com>
---
drivers/vhost/vringh.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
index 955d938eb663..7b8fd977f71c 100644
--- a/drivers/vhost/vringh.c
+++ b/drivers/vhost/vringh.c
@@ -123,8 +123,18 @@ 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;
- vringh_kiov_advance(iov, 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++;
+ }
}
return done;
}
--
2.41.0
Jason Wang
2023-Sep-26 02:57 UTC
[PATCH] vringh: don't use vringh_kiov_advance() in vringh_iov_xfer()
On Mon, Sep 25, 2023 at 6:31?PM Stefano Garzarella <sgarzare at redhat.com> wrote:> > In the while loop of vringh_iov_xfer(), `partlen` could be 0 if one of > the `iov` has 0 lenght. > In this case, we should skip the iov and go to the next one. > But calling vringh_kiov_advance() with 0 lenght does not cause the > advancement, since it returns immediately if asked to advance by 0 bytes. > > Let's restore the code that was there before commit b8c06ad4d67d > ("vringh: implement vringh_kiov_advance()"), avoiding using > vringh_kiov_advance(). > > Fixes: b8c06ad4d67d ("vringh: implement vringh_kiov_advance()") > Cc: stable at vger.kernel.org > Reported-by: Jason Wang <jasowang at redhat.com> > Signed-off-by: Stefano Garzarella <sgarzare at redhat.com>Acked-by: Jason Wang <jasowang at redhat.com> Thanks> --- > drivers/vhost/vringh.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > index 955d938eb663..7b8fd977f71c 100644 > --- a/drivers/vhost/vringh.c > +++ b/drivers/vhost/vringh.c > @@ -123,8 +123,18 @@ 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; > > - vringh_kiov_advance(iov, 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++; > + } > } > return done; > } > -- > 2.41.0 >