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@xxxxxxxxxxxxx>
---
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)
+
+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
+ }
+}
--
2.40.0
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