linux-kernel - Re: [PATCH v2] rust: sync: optimize rust symbol generation for CondVar

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Message-ID: <52e7d34e-cf86-40d6-a294-b318df98d72a@linux.dev>
Date: Tue, 25 Mar 2025 11:01:45 +0800
From: Kunwu Chan <kunwu.chan@...ux.dev>
To: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc: ojeda@...nel.org, alex.gaynor@...il.com, boqun.feng@...il.com,
 gary@...yguo.net, bjorn3_gh@...tonmail.com, benno.lossin@...ton.me,
 a.hindborg@...nel.org, aliceryhl@...gle.com, tmgross@...ch.edu,
 dakr@...nel.org, nathan@...nel.org, nick.desaulniers+lkml@...il.com,
 morbo@...gle.com, justinstitt@...gle.com, rust-for-linux@...r.kernel.org,
 linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
 Kunwu Chan <kunwu.chan@...mail.com>, Grace Deng <Grace.Deng006@...il.com>
Subject: Re: [PATCH v2] rust: sync: optimize rust symbol generation for
 CondVar

On 2025/3/24 17:37, Miguel Ojeda wrote:
> On Mon, Mar 24, 2025 at 7:19 AM Kunwu Chan<kunwu.chan@...ux.dev> wrote:
>> Link:https://github.com/Rust-for-Linux/linux/issues/1145
>> Suggested-by: Alice Ryhl<aliceryhl@...gle.com>
> Nit: I typically use Link after Suggested-by, to mimic what the docs
> require about Reported-by with Link. (No need to resend a new version
> just for this :)
Thanks for the kind reminder, I'll follow this next time
>> - Remove '#[inline]' for notify()
> It is good that the commit matches the log now, though I wonder if in
> the future we may want the `#[inline]` for `notify` anyway, even if
> LLVM does that one on its own today.
Now, the default '-Copt-level' is 2 when define 
'CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE',
and in  KBUILD_RUSTFLAGS the  '-Ccodegen-units' is 1.

So if the config not change, the result should be the same.

And the actualy compile steps for rust/kernel.o is as following:

make -f ./scripts/Makefile.build obj=rust
# RUSTC L rust/kernel.o
OBJTREE=/media/kunwuchan/68d922f3-5dde-45b0-af93-c45ba81d85ef/linux-next 
rustc --edition=2021 -Zbinary_dep_depinfo=y -Astable_features 
-Dnon_ascii_idents -Dunsafe_op_in_unsafe_fn -Wmissing_docs 
-Wrust_2018_idioms -Wunreachable_pub -Wclippy::all 
-Wclippy::ignored_unit_patterns -Wclippy::mut_mut 
-Wclippy::needless_bitwise_bool -Wclippy::needless_continue 
-Aclippy::needless_lifetimes -Wclippy::no_mangle_with_rust_abi 
-Wclippy::undocumented_unsafe_blocks 
-Wclippy::unnecessary_safety_comment -Wclippy::unnecessary_safety_doc 
-Wrustdoc::missing_crate_level_docs -Wrustdoc::unescaped_backticks 
-Cpanic=abort -Cembed-bitcode=n -Clto=n -Cforce-unwind-tables=n 
-Ccodegen-units=1 -Csymbol-mangling-version=v0 -Crelocation-model=static 
-Zfunction-sections=n -Wclippy::float_arithmetic 
--target=aarch64-unknown-none-softfloat -Cforce-unwind-tables=n 
-Zbranch-protection=bti,pac-ret -Copt-level=2 -Cdebug-assertions=y 
-Coverflow-checks=y -Cforce-frame-pointers=y -Cdebuginfo=1 
@./include/generated/rustc_cfg --extern ffi --extern pin_init --extern 
build_error --extern macros --extern bindings --extern uapi 
--emit=dep-info=rust/.kernel.o.d --emit=obj=rust/kernel.o 
--emit=metadata=rust/libkernel.rmeta --crate-type rlib -L./rust 
--crate-name kernel rust/kernel/lib.rs --sysroot=/dev/null
# EXPORTS rust/exports_kernel_generated.h
   llvm-nm -p --defined-only rust/kernel.o | awk '$2~/(T|R|D|B)/ && 
$3!~/__cfi/ && $3!~/__odr_asan/ { printf "EXPORT_SYMBOL_RUST_GPL(%s);
",$3 }' > rust/exports_kernel_generated.h

> Cheers,
> Miguel

-- 
Thanks,
   Kunwu.Chan(Tao.Chan)