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From: Jason Wang <jasowang@redhat.com>
To: Shunsuke Mie <mie@igel.co.jp>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	Rusty Russell <rusty@rustcorp.com.au>,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/9] vringh: remove vringh_iov and unite to vringh_kiov
Date: Tue, 27 Dec 2022 14:04:03 +0800	[thread overview]
Message-ID: <CACGkMEtAaYpuZtS0gx_m931nFzcvqSNK9BhvUZH_tZXTzjgQCg@mail.gmail.com> (raw)
In-Reply-To: <20221227022528.609839-3-mie@igel.co.jp>

On Tue, Dec 27, 2022 at 10:25 AM Shunsuke Mie <mie@igel.co.jp> wrote:
>
> 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>

While at this, I wonder if we need to go further, that is, switch to
using an iov iterator instead of a vringh customized one.

Thanks

> ---
>  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 828c29306565..aa3cd27d2384 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
>


WARNING: multiple messages have this Message-ID (diff)
From: Jason Wang <jasowang@redhat.com>
To: Shunsuke Mie <mie@igel.co.jp>
Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	netdev@vger.kernel.org, Rusty Russell <rusty@rustcorp.com.au>,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org
Subject: Re: [RFC PATCH 2/9] vringh: remove vringh_iov and unite to vringh_kiov
Date: Tue, 27 Dec 2022 14:04:03 +0800	[thread overview]
Message-ID: <CACGkMEtAaYpuZtS0gx_m931nFzcvqSNK9BhvUZH_tZXTzjgQCg@mail.gmail.com> (raw)
In-Reply-To: <20221227022528.609839-3-mie@igel.co.jp>

On Tue, Dec 27, 2022 at 10:25 AM Shunsuke Mie <mie@igel.co.jp> wrote:
>
> 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>

While at this, I wonder if we need to go further, that is, switch to
using an iov iterator instead of a vringh customized one.

Thanks

> ---
>  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 828c29306565..aa3cd27d2384 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
>

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  reply	other threads:[~2022-12-27  6:05 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-27  2:25 [RFC PATCH 0/6] Introduce a vringh accessor for IO memory Shunsuke Mie
2022-12-27  2:25 ` Shunsuke Mie
2022-12-27  2:25 ` [RFC PATCH 1/9] vringh: fix a typo in comments for vringh_kiov Shunsuke Mie
2022-12-27  2:25   ` Shunsuke Mie
2022-12-27  2:25 ` [RFC PATCH 2/9] vringh: remove vringh_iov and unite to vringh_kiov Shunsuke Mie
2022-12-27  2:25   ` Shunsuke Mie
2022-12-27  6:04   ` Jason Wang [this message]
2022-12-27  6:04     ` Jason Wang
2022-12-27  7:05     ` Michael S. Tsirkin
2022-12-27  7:05       ` Michael S. Tsirkin
2022-12-27  7:13       ` Shunsuke Mie
2022-12-27  7:13         ` Shunsuke Mie
2022-12-27  7:56         ` Michael S. Tsirkin
2022-12-27  7:56           ` Michael S. Tsirkin
2022-12-27  7:57           ` Shunsuke Mie
2022-12-27  7:57             ` Shunsuke Mie
2022-12-27  7:05     ` Shunsuke Mie
2022-12-27  7:05       ` Shunsuke Mie
2022-12-28  6:36       ` Jason Wang
2022-12-28  6:36         ` Jason Wang
2023-01-11  3:26         ` Shunsuke Mie
2023-01-11  3:26           ` Shunsuke Mie
2023-01-11  5:54           ` Jason Wang
2023-01-11  5:54             ` Jason Wang
2023-01-11  6:19             ` Shunsuke Mie
2023-01-11  6:19               ` Shunsuke Mie
2022-12-27  2:25 ` [RFC PATCH 3/9] tools/virtio: convert to new vringh user APIs Shunsuke Mie
2022-12-27  2:25   ` Shunsuke Mie
2022-12-27  2:25 ` [RFC PATCH 4/9] vringh: unify the APIs for all accessors Shunsuke Mie
2022-12-27  2:25   ` Shunsuke Mie
2022-12-27  7:04   ` Michael S. Tsirkin
2022-12-27  7:04     ` Michael S. Tsirkin
2022-12-27  7:49     ` Shunsuke Mie
2022-12-27  7:49       ` Shunsuke Mie
2022-12-27 10:22       ` Shunsuke Mie
2022-12-27 10:22         ` Shunsuke Mie
2022-12-27 14:37         ` Michael S. Tsirkin
2022-12-27 14:37           ` Michael S. Tsirkin
2022-12-28  2:24           ` Shunsuke Mie
2022-12-28  2:24             ` Shunsuke Mie
2022-12-28  7:20             ` Michael S. Tsirkin
2022-12-28  7:20               ` Michael S. Tsirkin
2023-01-11  4:10               ` Shunsuke Mie
2023-01-11  4:10                 ` Shunsuke Mie
2022-12-27  2:25 ` [RFC PATCH 5/9] tools/virtio: convert to use new unified vringh APIs Shunsuke Mie
2022-12-27  2:25   ` Shunsuke Mie
2022-12-27  2:25 ` [RFC PATCH 6/9] caif_virtio: convert to " Shunsuke Mie
2022-12-27  2:25   ` Shunsuke Mie

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