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| author |   Stefano Garzarella <sgarzare@redhat.com> | 2021-03-15 17:34:41 +0100 |
|---|---|---|
| committer |   Michael S. Tsirkin <mst@redhat.com> | 2021-05-03 04:55:53 -0400 |
| commit | b8c06ad4d67db56ed6bdfb685c134da74e92a2c7 (patch) | |
| tree | 6dc84edb70b95d4802140bb8ae04d0b234645484 /drivers/vhost/vringh.c | |
| parent | vringh: explain more about cleaning riov and wiov (diff) | |
| download | linux-dev-b8c06ad4d67db56ed6bdfb685c134da74e92a2c7.tar.xz linux-dev-b8c06ad4d67db56ed6bdfb685c134da74e92a2c7.zip | |
vringh: implement vringh_kiov_advance()
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>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210315163450.254396-6-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/vhost/vringh.c')
| -rw-r--r-- | drivers/vhost/vringh.c | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c index 2a88e087afd8..4af8fa259d65 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; } |