linux-kernel - [PATCH v2 3/3] rust: alloc: make `ReallocFunc::call` inline

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Message-ID: <20250105194054.545201-4-gary@garyguo.net>
Date: Sun,  5 Jan 2025 19:40:06 +0000
From: Gary Guo <gary@...yguo.net>
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>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Danilo Krummrich <dakr@...nel.org>
Cc: rust-for-linux@...r.kernel.org,
	llvm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] rust: alloc: make `ReallocFunc::call` inline

This function can be called with different function pointers when
different allocator (e.g. Kmalloc, Vmalloc, KVmalloc), however since
this function is not polymorphic, only one instance is generated,
and function pointers are used. Given that this function is called
for any Rust-side allocation/deallocation, performance matters a lot,
so making this function inlineable.

This is discovered when doing helper inlining work, since it's discovered
that even with helpers inlined, rust_helper_ symbols are still present
in final vmlinux binary, and it turns out this function is inhibiting
the inlining, and introducing indirect function calls.

Signed-off-by: Gary Guo <gary@...yguo.net>
---
 rust/kernel/alloc/allocator.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index 439985e29fbc..aa2dfa9dca4c 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -80,6 +80,7 @@ impl ReallocFunc {
     /// This method has the same guarantees as `Allocator::realloc`. Additionally
     /// - it accepts any pointer to a valid memory allocation allocated by this function.
     /// - memory allocated by this function remains valid until it is passed to this function.
+    #[inline]
     unsafe fn call(
         &self,
         ptr: Option<NonNull<u8>>,
-- 
2.47.0