Re: [PATCH v2] rust: add mark_used macro

On Thu, 1 Oct 2026 11:05:52 +0000
Alice Ryhl [off-list ref] wrote:

On Wed, Sep 30, 2026 at 06:50:28PM +0900, FUJITA Tomonori wrote:

quoted

quoted

diff --git a/rust/kernel/tracepoint.rs b/rust/kernel/tracepoint.rs
index c6e80aa99e8e..29d2d2d0aca8 100644
--- a/rust/kernel/tracepoint.rs
+++ b/rust/kernel/tracepoint.rs

@@ -38,9 +38,7 @@ macro_rules! declare_trace {
 
             #[cfg(not(CONFIG_TRACEPOINTS))]
             {
-                // If tracepoints are disabled, insert a trivial use of each argument
-                // to avoid unused argument warnings.
-                $( let _unused = $argname; )*
+                $crate::mark_used!($($argname),*);
             }
         }
     )*}

Gentle ping. Could you take a look at the tracepoint.rs part? If it
looks fine, I think it is easiest to take the patch through the Rust
tree.

Why are we adding this macro?

I think it's better to prefer avoiding macros if we can. The current
code is familiar to people who know Rust idioms, and now you are
replacing it with a kernel-specific macro that such people will not be
familiar with.

The macro was suggested by Miguel:

https://lore.kernel.org/rust-for-linux/CANiq72nWcqd3aSKdPqOSRRQBuwWNW-s2EOscYszQ9kSbmrKxcw@mail.gmail.com/ (local)

I think you also have a point.

Miguel, what do you think?