[PATCH] usb: rust: mark Device and Interface methods as inline

[PATCH] usb: rust: mark Device and Interface methods as inline

[Nicolás Antinori]

When building the kernel using llvm-19.1.7-rust-1.85.1-x86_64, the
following symbols are generated:

$ nm vmlinux | grep ' _R'.*usb.*Device | rustfilt
...
ffffffff823f2490 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::dec_ref
ffffffff823f2470 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::inc_ref
...

$ nm vmlinux | grep ' _R'.*usb.*Interface | rustfilt
ffffffff823f2450 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::dec_ref
ffffffff823f2430 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::inc_ref
...

However, these Rust symbols are trivial wrappers around the
`usb_get_dev`, `usb_put_dev`, `usb_get_intf` and `usb_put_intf`
functions. It doesn't make sense to go through a trivial wrapper
for these functions.

Link: https://github.com/Rust-for-Linux/linux/issues/1145
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>
---
 rust/kernel/usb.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
index 7aff0c82d0af..efbbee319b1a 100644
--- a/rust/kernel/usb.rs
+++ b/rust/kernel/usb.rs
@@ -393,6 +393,7 @@ fn as_ref(&self) -> &Device {
 
 // SAFETY: Instances of `Interface` are always reference-counted.
 unsafe impl AlwaysRefCounted for Interface {
+    #[inline]
     fn inc_ref(&self) {
         // SAFETY: The invariants of `Interface` guarantee that `self.as_raw()`
         // returns a valid `struct usb_interface` pointer, for which we will
@@ -400,6 +401,7 @@ fn inc_ref(&self) {
         unsafe { bindings::usb_get_intf(self.as_raw()) };
     }
 
+    #[inline]
     unsafe fn dec_ref(obj: NonNull<Self>) {
         // SAFETY: The safety requirements guarantee that the refcount is non-zero.
         unsafe { bindings::usb_put_intf(obj.cast().as_ptr()) }
@@ -444,6 +446,7 @@ fn as_raw(&self) -> *mut bindings::usb_device {
 
 // SAFETY: Instances of `Device` are always reference-counted.
 unsafe impl AlwaysRefCounted for Device {
+    #[inline]
     fn inc_ref(&self) {
         // SAFETY: The invariants of `Device` guarantee that `self.as_raw()`
         // returns a valid `struct usb_device` pointer, for which we will
@@ -451,6 +454,7 @@ fn inc_ref(&self) {
         unsafe { bindings::usb_get_dev(self.as_raw()) };
     }
 
+    #[inline]
     unsafe fn dec_ref(obj: NonNull<Self>) {
         // SAFETY: The safety requirements guarantee that the refcount is non-zero.
         unsafe { bindings::usb_put_dev(obj.cast().as_ptr()) }
-- 
2.47.3

Re: [PATCH] usb: rust: mark Device and Interface methods as inline

[Daniel Almeida]

> On 16 Jun 2026, at 19:36, Nicolás Antinori <nico.antinori.7@gmail.com> wrote:
> 
> When building the kernel using llvm-19.1.7-rust-1.85.1-x86_64, the
> following symbols are generated:
> 
> $ nm vmlinux | grep ' _R'.*usb.*Device | rustfilt
> ...
> ffffffff823f2490 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2470 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
> 
> $ nm vmlinux | grep ' _R'.*usb.*Interface | rustfilt
> ffffffff823f2450 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2430 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
> 
> However, these Rust symbols are trivial wrappers around the
> `usb_get_dev`, `usb_put_dev`, `usb_get_intf` and `usb_put_intf`
> functions. It doesn't make sense to go through a trivial wrapper
> for these functions.
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>
> ---
> rust/kernel/usb.rs | 4 ++++
> 1 file changed, 4 insertions(+)
> 
> diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
> index 7aff0c82d0af..efbbee319b1a 100644
> --- a/rust/kernel/usb.rs
> +++ b/rust/kernel/usb.rs
> @@ -393,6 +393,7 @@ fn as_ref(&self) -> &Device {
> 
> // SAFETY: Instances of `Interface` are always reference-counted.
> unsafe impl AlwaysRefCounted for Interface {
> +    #[inline]
>     fn inc_ref(&self) {
>         // SAFETY: The invariants of `Interface` guarantee that `self.as_raw()`
>         // returns a valid `struct usb_interface` pointer, for which we will
> @@ -400,6 +401,7 @@ fn inc_ref(&self) {
>         unsafe { bindings::usb_get_intf(self.as_raw()) };
>     }
> 
> +    #[inline]
>     unsafe fn dec_ref(obj: NonNull<Self>) {
>         // SAFETY: The safety requirements guarantee that the refcount is non-zero.
>         unsafe { bindings::usb_put_intf(obj.cast().as_ptr()) }
> @@ -444,6 +446,7 @@ fn as_raw(&self) -> *mut bindings::usb_device {
> 
> // SAFETY: Instances of `Device` are always reference-counted.
> unsafe impl AlwaysRefCounted for Device {
> +    #[inline]
>     fn inc_ref(&self) {
>         // SAFETY: The invariants of `Device` guarantee that `self.as_raw()`
>         // returns a valid `struct usb_device` pointer, for which we will
> @@ -451,6 +454,7 @@ fn inc_ref(&self) {
>         unsafe { bindings::usb_get_dev(self.as_raw()) };
>     }
> 
> +    #[inline]
>     unsafe fn dec_ref(obj: NonNull<Self>) {
>         // SAFETY: The safety requirements guarantee that the refcount is non-zero.
>         unsafe { bindings::usb_put_dev(obj.cast().as_ptr()) }
> -- 
> 2.47.3
> 
> 

Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>

Re: [PATCH] usb: rust: mark Device and Interface methods as inline

[Alice Ryhl]

On Tue, Jun 16, 2026 at 07:36:06PM -0300, Nicolás Antinori wrote:
> When building the kernel using llvm-19.1.7-rust-1.85.1-x86_64, the
> following symbols are generated:
> 
> $ nm vmlinux | grep ' _R'.*usb.*Device | rustfilt
> ...
> ffffffff823f2490 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2470 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
> 
> $ nm vmlinux | grep ' _R'.*usb.*Interface | rustfilt
> ffffffff823f2450 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2430 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
> 
> However, these Rust symbols are trivial wrappers around the
> `usb_get_dev`, `usb_put_dev`, `usb_get_intf` and `usb_put_intf`
> functions. It doesn't make sense to go through a trivial wrapper
> for these functions.
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>

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

Re: [PATCH] usb: rust: mark Device and Interface methods as inline

[Gary Guo]

On Tue Jun 16, 2026 at 11:36 PM BST, Nicolás Antinori wrote:
> When building the kernel using llvm-19.1.7-rust-1.85.1-x86_64, the
> following symbols are generated:
> 
> $ nm vmlinux | grep ' _R'.*usb.*Device | rustfilt
> ...
> ffffffff823f2490 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2470 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
> 
> $ nm vmlinux | grep ' _R'.*usb.*Interface | rustfilt
> ffffffff823f2450 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2430 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
> 
> However, these Rust symbols are trivial wrappers around the
> `usb_get_dev`, `usb_put_dev`, `usb_get_intf` and `usb_put_intf`
> functions. It doesn't make sense to go through a trivial wrapper
> for these functions.
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>

Reviewed-by: Gary Guo <gary@garyguo.net>

> ---
>  rust/kernel/usb.rs | 4 ++++
>  1 file changed, 4 insertions(+)

Re: [PATCH] usb: rust: mark Device and Interface methods as inline

[Miguel Ojeda]

On Wed, Jun 17, 2026 at 12:36 AM Nicolás Antinori
<nico.antinori.7@gmail.com> wrote:
>
> When building the kernel using llvm-19.1.7-rust-1.85.1-x86_64, the
> following symbols are generated:
>
> $ nm vmlinux | grep ' _R'.*usb.*Device | rustfilt
> ...
> ffffffff823f2490 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2470 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
>
> $ nm vmlinux | grep ' _R'.*usb.*Interface | rustfilt
> ffffffff823f2450 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2430 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
>
> However, these Rust symbols are trivial wrappers around the
> `usb_get_dev`, `usb_put_dev`, `usb_get_intf` and `usb_put_intf`
> functions. It doesn't make sense to go through a trivial wrapper
> for these functions.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>

Looks good, thanks -- I can pick this up, unless USB wants to route it
differently.

Cheers,
Miguel

Re: [PATCH] usb: rust: mark Device and Interface methods as inline

[Danilo Krummrich]

(Cc: Greg, linux-usb)

Looks like the Rust USB code wasn't added to the USB MAINTAINERS entry.

On Wed Jun 17, 2026 at 12:36 AM CEST, Nicolás Antinori wrote:
> When building the kernel using llvm-19.1.7-rust-1.85.1-x86_64, the
> following symbols are generated:
>
> $ nm vmlinux | grep ' _R'.*usb.*Device | rustfilt
> ...
> ffffffff823f2490 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2470 T <kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
>
> $ nm vmlinux | grep ' _R'.*usb.*Interface | rustfilt
> ffffffff823f2450 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::dec_ref
> ffffffff823f2430 T <kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::inc_ref
> ...
>
> However, these Rust symbols are trivial wrappers around the
> `usb_get_dev`, `usb_put_dev`, `usb_get_intf` and `usb_put_intf`
> functions. It doesn't make sense to go through a trivial wrapper
> for these functions.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>

Re: [PATCH] usb: rust: mark Device and Interface methods as inline

[Greg Kroah-Hartman]

On Wed, Jun 17, 2026 at 05:34:02PM +0200, Danilo Krummrich wrote:
> (Cc: Greg, linux-usb)
> 
> Looks like the Rust USB code wasn't added to the USB MAINTAINERS entry.

Yeah, we should fix that.  As it didn't actually work I wasn't too
worried about it yet :)

I'll knock up a patch later this week.

thanks,

greg k-h