[PATCH v2] rust/kernel/faux: mark Registration methods inline

[PATCH v2] rust/kernel/faux: mark Registration methods inline

[Ethan Carter Edwards]

When building the kernel on Arch Linux using on x86_64 with tools:
$ rustc --version
rustc 1.84.0 (9fc6b4312 2025-01-07)
$ cargo --version
cargo 1.84.0 (66221abde 2024-11-19)
$ clang --version
clang version 19.1.7
Target: x86_64-pc-linux-gnu

The following symbols are generated:
$ nm vmlinux | rg ' _R' | rustfilt | rg faux
ffffffff81959ae0 T <kernel::faux::Registration>::new
ffffffff81959b40 T <kernel::faux::Registration as core::ops::drop::Drop>::drop

However, these Rust symbols are wrappers around bindings in the C faux
code. Inlining these functions removes the middle-man wrapper function
After applying this patch, the above function signatures disappear.

Link: https://github.com/Rust-for-Linux/linux/issues/1145
Signed-off-by: Ethan Carter Edwards <ethan@ethancedwards.com>
---
v2: rebase on linux-next-20250307
---
 rust/kernel/faux.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rust/kernel/faux.rs b/rust/kernel/faux.rs
index 3277f35c3f79..8a50fcd4c9bb 100644
--- a/rust/kernel/faux.rs
+++ b/rust/kernel/faux.rs
@@ -23,6 +23,7 @@
 
 impl Registration {
     /// Create and register a new faux device with the given name.
+    #[inline]
     pub fn new(name: &CStr, parent: Option<&device::Device>) -> Result<Self> {
         // SAFETY:
         // - `name` is copied by this function into its own storage
@@ -58,6 +59,7 @@ fn as_ref(&self) -> &device::Device {
 }
 
 impl Drop for Registration {
+    #[inline]
     fn drop(&mut self) {
         // SAFETY: `self.0` is a valid registered faux_device via our type invariants.
         unsafe { bindings::faux_device_destroy(self.as_raw()) }
-- 
2.48.1

Re: [PATCH v2] rust/kernel/faux: mark Registration methods inline

[Danilo Krummrich]

On Mon, Mar 10, 2025 at 03:51:38PM -0400, Ethan Carter Edwards wrote:
> When building the kernel on Arch Linux using on x86_64 with tools:
> $ rustc --version
> rustc 1.84.0 (9fc6b4312 2025-01-07)
> $ cargo --version
> cargo 1.84.0 (66221abde 2024-11-19)
> $ clang --version
> clang version 19.1.7
> Target: x86_64-pc-linux-gnu
> 
> The following symbols are generated:
> $ nm vmlinux | rg ' _R' | rustfilt | rg faux
> ffffffff81959ae0 T <kernel::faux::Registration>::new
> ffffffff81959b40 T <kernel::faux::Registration as core::ops::drop::Drop>::drop
> 
> However, these Rust symbols are wrappers around bindings in the C faux
> code. Inlining these functions removes the middle-man wrapper function
> After applying this patch, the above function signatures disappear.
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Signed-off-by: Ethan Carter Edwards <ethan@ethancedwards.com>

Acked-by: Danilo Krummrich <dakr@kernel.org>

Re: [PATCH v2] rust/kernel/faux: mark Registration methods inline

[Alice Ryhl]

On Mon, Mar 10, 2025 at 03:51:38PM -0400, Ethan Carter Edwards wrote:
> When building the kernel on Arch Linux using on x86_64 with tools:
> $ rustc --version
> rustc 1.84.0 (9fc6b4312 2025-01-07)
> $ cargo --version
> cargo 1.84.0 (66221abde 2024-11-19)

Is there a reason you didn't drop this from the commit message?

> $ clang --version
> clang version 19.1.7
> Target: x86_64-pc-linux-gnu
> 
> The following symbols are generated:
> $ nm vmlinux | rg ' _R' | rustfilt | rg faux
> ffffffff81959ae0 T <kernel::faux::Registration>::new
> ffffffff81959b40 T <kernel::faux::Registration as core::ops::drop::Drop>::drop
> 
> However, these Rust symbols are wrappers around bindings in the C faux
> code. Inlining these functions removes the middle-man wrapper function
> After applying this patch, the above function signatures disappear.
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Signed-off-by: Ethan Carter Edwards <ethan@ethancedwards.com>

On v1 I replied with:

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

So you should add that to the commit message when you send a new
version. :)

(Unless there are changes that require me to review it again.)

Alice

Re: [PATCH v2] rust/kernel/faux: mark Registration methods inline

[Ethan Carter Edwards]

On 25/03/11 08:06AM, Alice Ryhl wrote:
> On Mon, Mar 10, 2025 at 03:51:38PM -0400, Ethan Carter Edwards wrote:
> > When building the kernel on Arch Linux using on x86_64 with tools:
> > $ rustc --version
> > rustc 1.84.0 (9fc6b4312 2025-01-07)
> > $ cargo --version
> > cargo 1.84.0 (66221abde 2024-11-19)
> 
> Is there a reason you didn't drop this from the commit message?

I wasn't sure if the authoritative answer was to drop it. I will not
include it from now on. Thanks.

> 
> > $ clang --version
> > clang version 19.1.7
> > Target: x86_64-pc-linux-gnu
> > 
> > The following symbols are generated:
> > $ nm vmlinux | rg ' _R' | rustfilt | rg faux
> > ffffffff81959ae0 T <kernel::faux::Registration>::new
> > ffffffff81959b40 T <kernel::faux::Registration as core::ops::drop::Drop>::drop
> > 
> > However, these Rust symbols are wrappers around bindings in the C faux
> > code. Inlining these functions removes the middle-man wrapper function
> > After applying this patch, the above function signatures disappear.
> > 
> > Link: https://github.com/Rust-for-Linux/linux/issues/1145
> > Signed-off-by: Ethan Carter Edwards <ethan@ethancedwards.com>
> 
> On v1 I replied with:
> 
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> 
> So you should add that to the commit message when you send a new
> version. :)

My apologies. I forgot to include it, as b4 usually pulls them down for
me and I was just using format-patch and mutt to send v2. 

> 
> (Unless there are changes that require me to review it again.)
> 
> Alice

Thanks for applying the patch, Greg.

Thanks everyone for their help. Rust in the kernel isn't as scary as it
seems! I'll be back to help some more ;).