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authorAsahi Lina <lina@asahilina.net>2023-04-03 19:01:11 +0900
committerMiguel Ojeda <ojeda@kernel.org>2023-04-10 23:55:43 +0200
commit1edd03378e50ff1071004c80cb878e4bad73a68f (patch)
treeccd32bd6275976b743750e3c6aa454bcf4d906d0 /rust
parent39867fec2855cf37e5542dc6a972bce8ee191a9c (diff)
rust: sync: arc: Implement Arc<dyn Any + Send + Sync>::downcast()
This mirrors the standard library's alloc::sync::Arc::downcast(). Based on the Rust standard library implementation, ver 1.62.0, licensed under "Apache-2.0 OR MIT", from: https://github.com/rust-lang/rust/tree/1.62.0/library/alloc/src For copyright details, please see: https://github.com/rust-lang/rust/blob/1.62.0/COPYRIGHT Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Asahi Lina <lina@asahilina.net> Link: https://lore.kernel.org/r/20230224-rust-arc-v2-1-5c97a865b276@asahilina.net [ Moved `mod std_vendor;` up. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
-rw-r--r--rust/kernel/sync/arc.rs2
-rw-r--r--rust/kernel/sync/arc/std_vendor.rs28
2 files changed, 30 insertions, 0 deletions
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index a94e303217c6..4ab9b280cb3d 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -30,6 +30,8 @@ use core::{
ptr::NonNull,
};
+mod std_vendor;
+
/// A reference-counted pointer to an instance of `T`.
///
/// The reference count is incremented when new instances of [`Arc`] are created, and decremented
diff --git a/rust/kernel/sync/arc/std_vendor.rs b/rust/kernel/sync/arc/std_vendor.rs
new file mode 100644
index 000000000000..a66a0c2831b3
--- /dev/null
+++ b/rust/kernel/sync/arc/std_vendor.rs
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! The contents of this file come from the Rust standard library, hosted in
+//! the <https://github.com/rust-lang/rust> repository, licensed under
+//! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,
+//! see <https://github.com/rust-lang/rust/blob/master/COPYRIGHT>.
+
+use crate::sync::{arc::ArcInner, Arc};
+use core::any::Any;
+
+impl Arc<dyn Any + Send + Sync> {
+ /// Attempt to downcast the `Arc<dyn Any + Send + Sync>` to a concrete type.
+ pub fn downcast<T>(self) -> core::result::Result<Arc<T>, Self>
+ where
+ T: Any + Send + Sync,
+ {
+ if (*self).is::<T>() {
+ // SAFETY: We have just checked that the type is correct, so we can cast the pointer.
+ unsafe {
+ let ptr = self.ptr.cast::<ArcInner<T>>();
+ core::mem::forget(self);
+ Ok(Arc::from_inner(ptr))
+ }
+ } else {
+ Err(self)
+ }
+ }
+}