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Message-Id: <20241104-borrow-mut-v2-1-de650678648d@gmail.com>
Date: Mon, 04 Nov 2024 17:20:27 -0400
From: Tamir Duberstein <tamird@...il.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
Tamir Duberstein <tamird@...il.com>
Subject: [PATCH v2 1/6] rust: arc: use `NonNull::new_unchecked`
There is no need to check (and panic on violations of) the safety
requirements on `ForeignOwnable` functions. Avoiding the check is
consistent with the implementation of `ForeignOwnable` for `Box`.
Signed-off-by: Tamir Duberstein <tamird@...il.com>
Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
---
rust/kernel/sync/arc.rs | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index db9da352d588f65348aa7a5204abbb165b70197f..2c9b7d4a2554278ce8608f4f4c7f9cfe87b21492 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -337,9 +337,9 @@ fn into_foreign(self) -> *const core::ffi::c_void {
}
unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> ArcBorrow<'a, T> {
- // By the safety requirement of this function, we know that `ptr` came from
- // a previous call to `Arc::into_foreign`.
- let inner = NonNull::new(ptr as *mut ArcInner<T>).unwrap();
+ // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
+ // call to `Self::into_foreign`.
+ let inner = unsafe { NonNull::new_unchecked(ptr as *mut ArcInner<T>) };
// SAFETY: The safety requirements of `from_foreign` ensure that the object remains alive
// for the lifetime of the returned value.
@@ -347,10 +347,14 @@ unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> ArcBorrow<'a, T> {
}
unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+ // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
+ // call to `Self::into_foreign`.
+ let inner = unsafe { NonNull::new_unchecked(ptr as *mut ArcInner<T>) };
+
// SAFETY: By the safety requirement of this function, we know that `ptr` came from
// a previous call to `Arc::into_foreign`, which guarantees that `ptr` is valid and
// holds a reference count increment that is transferrable to us.
- unsafe { Self::from_inner(NonNull::new(ptr as _).unwrap()) }
+ unsafe { Self::from_inner(inner) }
}
}
--
2.47.0
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