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    Subject[RFC PATCH v2 3/7] vringh: remove vringh_iov and unite to vringh_kiov
    Date
    struct vringh_iov is defined to hold userland addresses. However, to use
    common function, __vring_iov, finally the vringh_iov converts to the
    vringh_kiov with simple cast. It includes compile time check code to make
    sure it can be cast correctly.

    To simplify the code, this patch removes the struct vringh_iov and unifies
    APIs to struct vringh_kiov.

    Signed-off-by: Shunsuke Mie <mie@igel.co.jp>
    ---
    drivers/vhost/vringh.c | 32 ++++++------------------------
    include/linux/vringh.h | 45 ++++--------------------------------------
    2 files changed, 10 insertions(+), 67 deletions(-)

    diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
    index 33eb941fcf15..bcdbde1d484e 100644
    --- a/drivers/vhost/vringh.c
    +++ b/drivers/vhost/vringh.c
    @@ -691,8 +691,8 @@ EXPORT_SYMBOL(vringh_init_user);
    * calling vringh_iov_cleanup() to release the memory, even on error!
    */
    int vringh_getdesc_user(struct vringh *vrh,
    - struct vringh_iov *riov,
    - struct vringh_iov *wiov,
    + struct vringh_kiov *riov,
    + struct vringh_kiov *wiov,
    bool (*getrange)(struct vringh *vrh,
    u64 addr, struct vringh_range *r),
    u16 *head)
    @@ -708,26 +708,6 @@ int vringh_getdesc_user(struct vringh *vrh,
    if (err == vrh->vring.num)
    return 0;

    - /* We need the layouts to be the identical for this to work */
    - BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
    - BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
    - offsetof(struct vringh_iov, iov));
    - BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
    - offsetof(struct vringh_iov, i));
    - BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
    - offsetof(struct vringh_iov, used));
    - BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
    - offsetof(struct vringh_iov, max_num));
    - BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
    - BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
    - offsetof(struct kvec, iov_base));
    - BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
    - offsetof(struct kvec, iov_len));
    - BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
    - != sizeof(((struct kvec *)NULL)->iov_base));
    - BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
    - != sizeof(((struct kvec *)NULL)->iov_len));
    -
    *head = err;
    err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
    (struct vringh_kiov *)wiov,
    @@ -740,14 +720,14 @@ int vringh_getdesc_user(struct vringh *vrh,
    EXPORT_SYMBOL(vringh_getdesc_user);

    /**
    - * vringh_iov_pull_user - copy bytes from vring_iov.
    + * vringh_iov_pull_user - copy bytes from vring_kiov.
    * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
    * @dst: the place to copy.
    * @len: the maximum length to copy.
    *
    * Returns the bytes copied <= len or a negative errno.
    */
    -ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
    +ssize_t vringh_iov_pull_user(struct vringh_kiov *riov, void *dst, size_t len)
    {
    return vringh_iov_xfer(NULL, (struct vringh_kiov *)riov,
    dst, len, xfer_from_user);
    @@ -755,14 +735,14 @@ ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
    EXPORT_SYMBOL(vringh_iov_pull_user);

    /**
    - * vringh_iov_push_user - copy bytes into vring_iov.
    + * vringh_iov_push_user - copy bytes into vring_kiov.
    * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
    * @src: the place to copy from.
    * @len: the maximum length to copy.
    *
    * Returns the bytes copied <= len or a negative errno.
    */
    -ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
    +ssize_t vringh_iov_push_user(struct vringh_kiov *wiov,
    const void *src, size_t len)
    {
    return vringh_iov_xfer(NULL, (struct vringh_kiov *)wiov,
    diff --git a/include/linux/vringh.h b/include/linux/vringh.h
    index 1991a02c6431..733d948e8123 100644
    --- a/include/linux/vringh.h
    +++ b/include/linux/vringh.h
    @@ -79,18 +79,6 @@ struct vringh_range {
    u64 offset;
    };

    -/**
    - * struct vringh_iov - iovec mangler.
    - *
    - * Mangles iovec in place, and restores it.
    - * Remaining data is iov + i, of used - i elements.
    - */
    -struct vringh_iov {
    - struct iovec *iov;
    - size_t consumed; /* Within iov[i] */
    - unsigned i, used, max_num;
    -};
    -
    /**
    * struct vringh_kiov - kvec mangler.
    *
    @@ -113,44 +101,19 @@ int vringh_init_user(struct vringh *vrh, u64 features,
    vring_avail_t __user *avail,
    vring_used_t __user *used);

    -static inline void vringh_iov_init(struct vringh_iov *iov,
    - struct iovec *iovec, unsigned num)
    -{
    - iov->used = iov->i = 0;
    - iov->consumed = 0;
    - iov->max_num = num;
    - iov->iov = iovec;
    -}
    -
    -static inline void vringh_iov_reset(struct vringh_iov *iov)
    -{
    - iov->iov[iov->i].iov_len += iov->consumed;
    - iov->iov[iov->i].iov_base -= iov->consumed;
    - iov->consumed = 0;
    - iov->i = 0;
    -}
    -
    -static inline void vringh_iov_cleanup(struct vringh_iov *iov)
    -{
    - if (iov->max_num & VRINGH_IOV_ALLOCATED)
    - kfree(iov->iov);
    - iov->max_num = iov->used = iov->i = iov->consumed = 0;
    - iov->iov = NULL;
    -}
    -
    /* Convert a descriptor into iovecs. */
    int vringh_getdesc_user(struct vringh *vrh,
    - struct vringh_iov *riov,
    - struct vringh_iov *wiov,
    + struct vringh_kiov *riov,
    + struct vringh_kiov *wiov,
    bool (*getrange)(struct vringh *vrh,
    u64 addr, struct vringh_range *r),
    u16 *head);

    /* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
    -ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len);
    +ssize_t vringh_iov_pull_user(struct vringh_kiov *riov, void *dst, size_t len);

    /* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
    -ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
    +ssize_t vringh_iov_push_user(struct vringh_kiov *wiov,
    const void *src, size_t len);

    /* Mark a descriptor as used. */
    --
    2.25.1
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