[v2,1/2] rust: add scatterlist support
Commit Message
This patch adds a scatterlist abstraction. It is then used and tested
by the new rust virtio sample module.
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
---
rust/kernel/lib.rs | 1 +
rust/kernel/scatterlist.rs | 40 ++++++++++++++++++++++++++++++++++++++
2 files changed, 41 insertions(+)
create mode 100644 rust/kernel/scatterlist.rs
Comments
On 4/5/23 17:14, Daniel Almeida wrote:
> This patch adds a scatterlist abstraction. It is then used and tested
> by the new rust virtio sample module.
>
> Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
> ---
> rust/kernel/lib.rs | 1 +
> rust/kernel/scatterlist.rs | 40 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 41 insertions(+)
> create mode 100644 rust/kernel/scatterlist.rs
>
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index c20b37e88ab2..b23be69919cc 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -71,6 +71,7 @@ pub mod net;
> pub mod pages;
> pub mod power;
> pub mod revocable;
> +pub mod scatterlist;
> pub mod security;
> pub mod task;
> pub mod workqueue;
> diff --git a/rust/kernel/scatterlist.rs b/rust/kernel/scatterlist.rs
> new file mode 100644
> index 000000000000..fe036af13995
> --- /dev/null
> +++ b/rust/kernel/scatterlist.rs
> @@ -0,0 +1,40 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! Scatterlist abstractions.
> +//!
> +//! C header: [`include/linux/virtio.h`](../../../../include/linux/scatterlist.h)
Little typo, I think that you've meant this to be scatterlist.h instead
of virtio.h.
> +
> +use core::cell::UnsafeCell;
> +
> +/// Scatterlist abstraction over the C side `struct scatterlist`.
> +pub struct Scatterlist {
> + /// The C side `struct scatterlist`.
> + inner: UnsafeCell<bindings::scatterlist>,
> +}
> +
Wouldn't be better to use a transparent tuple struct [1] since this only
has one non-zero sized field and could be easily transmuted into its
inner type.
> +impl Scatterlist {
> + /// A wrapper over the C-side `sg_init_one()`. Initialize a single entry sg
> + /// list.
> + ///
> + /// # Safety
> + ///
> + /// Caller must ensure that `buf` is valid and `buflen` really
> + /// represents the size of `buf`.
> + pub unsafe fn init_one(buf: *const core::ffi::c_void, buflen: u32) -> Self {
> + // SAFETY: There are no references or function pointers in this
> + // `Scatterlist`.
> + let mut sg: Scatterlist = unsafe { core::mem::zeroed() };
> + // SAFETY: we pass a valid sg entry, which points to stack-allocated
> + // variable above. `buf` and `buflen` are presumed valid as per this
> + // function's safety requirements.
> + unsafe {
> + bindings::sg_init_one(sg.inner.get_mut(), buf, buflen);
> + }
> +
> + sg
> + }
If this function was meant to be used for internal use only then it
should be `pub(crate)`, or else, a function that takes an slice should
be provided as a safe alternative.
> +
> + pub(crate) fn inner(&self) -> &UnsafeCell<bindings::scatterlist> {
> + &self.inner
> + }
> +}
Link: https://doc.rust-lang.org/nomicon/other-reprs.html#reprtransparent [1]
Regards
-> Martin
@@ -71,6 +71,7 @@ pub mod net;
pub mod pages;
pub mod power;
pub mod revocable;
+pub mod scatterlist;
pub mod security;
pub mod task;
pub mod workqueue;
new file mode 100644
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Scatterlist abstractions.
+//!
+//! C header: [`include/linux/virtio.h`](../../../../include/linux/scatterlist.h)
+
+use core::cell::UnsafeCell;
+
+/// Scatterlist abstraction over the C side `struct scatterlist`.
+pub struct Scatterlist {
+ /// The C side `struct scatterlist`.
+ inner: UnsafeCell<bindings::scatterlist>,
+}
+
+impl Scatterlist {
+ /// A wrapper over the C-side `sg_init_one()`. Initialize a single entry sg
+ /// list.
+ ///
+ /// # Safety
+ ///
+ /// Caller must ensure that `buf` is valid and `buflen` really
+ /// represents the size of `buf`.
+ pub unsafe fn init_one(buf: *const core::ffi::c_void, buflen: u32) -> Self {
+ // SAFETY: There are no references or function pointers in this
+ // `Scatterlist`.
+ let mut sg: Scatterlist = unsafe { core::mem::zeroed() };
+ // SAFETY: we pass a valid sg entry, which points to stack-allocated
+ // variable above. `buf` and `buflen` are presumed valid as per this
+ // function's safety requirements.
+ unsafe {
+ bindings::sg_init_one(sg.inner.get_mut(), buf, buflen);
+ }
+
+ sg
+ }
+
+ pub(crate) fn inner(&self) -> &UnsafeCell<bindings::scatterlist> {
+ &self.inner
+ }
+}