[PATCH v17 07/11] rust: debugfs: use `kernel::fmt`

Tamir Duberstein
2025-10-15T19:25:16Z

Reduce coupling to implementation details of the formatting machinery by
avoiding direct use for `core`'s formatting traits and macros.

This backslid in commit 40ecc49466c8 ("rust: debugfs: Add support for
callback-based files") and commit 5e40b591cb46 ("rust: debugfs: Add
support for read-only files").

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
rust/kernel/debugfs.rs | 2 +-
rust/kernel/debugfs/callback_adapters.rs | 7 +++----
rust/kernel/debugfs/file_ops.rs | 6 +++---
rust/kernel/debugfs/traits.rs | 10 +++++-----
4 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/rust/kernel/debugfs.rs b/rust/kernel/debugfs.rs
index 381c23b3dd83..8c35d032acfe 100644
--- a/rust/kernel/debugfs.rs
+++ b/rust/kernel/debugfs.rs
@@ -8,12 +8,12 @@
// When DebugFS is disabled, many parameters are dead. Linting for this isn't helpful.
#![cfg_attr(not(CONFIG_DEBUG_FS), allow(unused_variables))]

+use crate::fmt;
use crate::prelude::*;
use crate::str::CStr;
#[cfg(CONFIG_DEBUG_FS)]
use crate::sync::Arc;
use crate::uaccess::UserSliceReader;
-use core::fmt;
use core::marker::PhantomData;
use core::marker::PhantomPinned;
#[cfg(CONFIG_DEBUG_FS)]
diff --git a/rust/kernel/debugfs/callback_adapters.rs b/rust/kernel/debugfs/callback_adapters.rs
index 6c024230f676..a260d8dee051 100644
--- a/rust/kernel/debugfs/callback_adapters.rs
+++ b/rust/kernel/debugfs/callback_adapters.rs
@@ -5,10 +5,9 @@
//! than a trait implementation. If provided, it will override the trait implementation.

use super::{Reader, Writer};
+use crate::fmt;
use crate::prelude::*;
use crate::uaccess::UserSliceReader;
-use core::fmt;
-use core::fmt::Formatter;
use core::marker::PhantomData;
use core::ops::Deref;

@@ -76,9 +75,9 @@ fn deref(&self) -> &D {

impl<D, F> Writer for FormatAdapter<D, F>
where
- F: Fn(&D, &mut Formatter<'_>) -> fmt::Result + 'static,
+ F: Fn(&D, &mut fmt::Formatter<'_>) -> fmt::Result + 'static,
{
- fn write(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
+ fn write(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
// SAFETY: FormatAdapter<_, F> can only be constructed if F is inhabited
let f: &F = unsafe { materialize_zst() };
f(&self.inner, fmt)
diff --git a/rust/kernel/debugfs/file_ops.rs b/rust/kernel/debugfs/file_ops.rs
index 50fead17b6f3..9ad5e3fa6f69 100644
--- a/rust/kernel/debugfs/file_ops.rs
+++ b/rust/kernel/debugfs/file_ops.rs
@@ -3,11 +3,11 @@

use super::{Reader, Writer};
use crate::debugfs::callback_adapters::Adapter;
+use crate::fmt;
use crate::prelude::*;
use crate::seq_file::SeqFile;
use crate::seq_print;
use crate::uaccess::UserSlice;
-use core::fmt::{Display, Formatter, Result};
use core::marker::PhantomData;

#[cfg(CONFIG_DEBUG_FS)]
@@ -65,8 +65,8 @@ fn deref(&self) -> &Self::Target {

struct WriterAdapter<T>(T);

-impl<'a, T: Writer> Display for WriterAdapter<&'a T> {
- fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+impl<'a, T: Writer> fmt::Display for WriterAdapter<&'a T> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.write(f)
}
}
diff --git a/rust/kernel/debugfs/traits.rs b/rust/kernel/debugfs/traits.rs
index ab009eb254b3..ad33bfbc7669 100644
--- a/rust/kernel/debugfs/traits.rs
+++ b/rust/kernel/debugfs/traits.rs
@@ -3,10 +3,10 @@

//! Traits for rendering or updating values exported to DebugFS.

+use crate::fmt;
use crate::prelude::*;
use crate::sync::Mutex;
use crate::uaccess::UserSliceReader;
-use core::fmt::{self, Debug, Formatter};
use core::str::FromStr;
use core::sync::atomic::{
AtomicI16, AtomicI32, AtomicI64, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU64,
@@ -24,17 +24,17 @@
/// explicitly instead.
pub trait Writer {
/// Formats the value using the given formatter.
- fn write(&self, f: &mut Formatter<'_>) -> fmt::Result;
+ fn write(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result;
}

impl<T: Writer> Writer for Mutex<T> {
- fn write(&self, f: &mut Formatter<'_>) -> fmt::Result {
+ fn write(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.lock().write(f)
}
}

-impl<T: Debug> Writer for T {
- fn write(&self, f: &mut Formatter<'_>) -> fmt::Result {
+impl<T: fmt::Debug> Writer for T {
+ fn write(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
writeln!(f, "{self:?}")
}
}

--
2.51.0