rust: debugfs: Replace the usage of Rust native atomics

Rust native atomics are not allowed to use in kernel due to the mismatch
of memory model with Linux kernel memory model, hence remove the usage
of Rust native atomics in debufs.

Reviewed-by: Matthew Maurer <mmaurer@google.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Tested-by: David Gow <davidgow@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://patch.msgid.link/20251022035324.70785-4-boqun.feng@gmail.com

diff --git a/rust/kernel/debugfs/traits.rs b/rust/kernel/debugfs/traits.rs
index ba7ec5a900b8fb2ad32284e52e18b42794af8b86..92054fed2136fe1dec0eec2e3402ac84b32246cb 100644 (file)
--- a/rust/kernel/debugfs/traits.rs
+++ b/rust/kernel/debugfs/traits.rs
@@ -4,14 +4,11 @@
 //! Traits for rendering or updating values exported to DebugFS.
 
 use crate::prelude::*;
+use crate::sync::atomic::{Atomic, AtomicBasicOps, AtomicType, Relaxed};
 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,
-    AtomicU8, AtomicUsize, Ordering,
-};
 
 /// A trait for types that can be written into a string.
 ///
@@ -66,37 +63,21 @@ impl<T: FromStr + Unpin> Reader for Mutex<T> {
     }
 }
 
-macro_rules! impl_reader_for_atomic {
-    ($(($atomic_type:ty, $int_type:ty)),*) => {
-        $(
-            impl Reader for $atomic_type {
-                fn read_from_slice(&self, reader: &mut UserSliceReader) -> Result {
-                    let mut buf = [0u8; 21]; // Enough for a 64-bit number.
-                    if reader.len() > buf.len() {
-                        return Err(EINVAL);
-                    }
-                    let n = reader.len();
-                    reader.read_slice(&mut buf[..n])?;
+impl<T: AtomicType + FromStr> Reader for Atomic<T>
+where
+    T::Repr: AtomicBasicOps,
+{
+    fn read_from_slice(&self, reader: &mut UserSliceReader) -> Result {
+        let mut buf = [0u8; 21]; // Enough for a 64-bit number.
+        if reader.len() > buf.len() {
+            return Err(EINVAL);
+        }
+        let n = reader.len();
+        reader.read_slice(&mut buf[..n])?;
 
-                    let s = core::str::from_utf8(&buf[..n]).map_err(|_| EINVAL)?;
-                    let val = s.trim().parse::<$int_type>().map_err(|_| EINVAL)?;
-                    self.store(val, Ordering::Relaxed);
-                    Ok(())
-                }
-            }
-        )*
-    };
+        let s = core::str::from_utf8(&buf[..n]).map_err(|_| EINVAL)?;
+        let val = s.trim().parse::<T>().map_err(|_| EINVAL)?;
+        self.store(val, Relaxed);
+        Ok(())
+    }
 }
-
-impl_reader_for_atomic!(
-    (AtomicI16, i16),
-    (AtomicI32, i32),
-    (AtomicI64, i64),
-    (AtomicI8, i8),
-    (AtomicIsize, isize),
-    (AtomicU16, u16),
-    (AtomicU32, u32),
-    (AtomicU64, u64),
-    (AtomicU8, u8),
-    (AtomicUsize, usize)
-);

diff --git a/samples/rust/rust_debugfs.rs b/samples/rust/rust_debugfs.rs
index 82b61a15a34b9561a70322a9f54d44a17f34778f..711faa07bece3e9e487acae9f754dfde708bc831 100644 (file)
--- a/samples/rust/rust_debugfs.rs
+++ b/samples/rust/rust_debugfs.rs
@@ -32,14 +32,12 @@
 //! ```
 
 use core::str::FromStr;
-use core::sync::atomic::AtomicUsize;
-use core::sync::atomic::Ordering;
 use kernel::c_str;
 use kernel::debugfs::{Dir, File};
 use kernel::new_mutex;
 use kernel::prelude::*;
+use kernel::sync::atomic::{Atomic, Relaxed};
 use kernel::sync::Mutex;
-
 use kernel::{acpi, device::Core, of, platform, str::CString, types::ARef};
 
 kernel::module_platform_driver! {
@@ -59,7 +57,7 @@ struct RustDebugFs {
     #[pin]
     _compatible: File<CString>,
     #[pin]
-    counter: File<AtomicUsize>,
+    counter: File<Atomic<usize>>,
     #[pin]
     inner: File<Mutex<Inner>>,
 }
@@ -109,7 +107,7 @@ impl platform::Driver for RustDebugFs {
     ) -> Result<Pin<KBox<Self>>> {
         let result = KBox::try_pin_init(RustDebugFs::new(pdev), GFP_KERNEL)?;
         // We can still mutate fields through the files which are atomic or mutexed:
-        result.counter.store(91, Ordering::Relaxed);
+        result.counter.store(91, Relaxed);
         {
             let mut guard = result.inner.lock();
             guard.x = guard.y;
@@ -120,8 +118,8 @@ impl platform::Driver for RustDebugFs {
 }
 
 impl RustDebugFs {
-    fn build_counter(dir: &Dir) -> impl PinInit<File<AtomicUsize>> + '_ {
-        dir.read_write_file(c_str!("counter"), AtomicUsize::new(0))
+    fn build_counter(dir: &Dir) -> impl PinInit<File<Atomic<usize>>> + '_ {
+        dir.read_write_file(c_str!("counter"), Atomic::<usize>::new(0))
     }
 
     fn build_inner(dir: &Dir) -> impl PinInit<File<Mutex<Inner>>> + '_ {

diff --git a/samples/rust/rust_debugfs_scoped.rs b/samples/rust/rust_debugfs_scoped.rs
index b0c4e76b123eaa161add593818bebe9072cfe78e..9f0ec5f24cda8614a2666c07280b7010627611e7 100644 (file)
--- a/samples/rust/rust_debugfs_scoped.rs
+++ b/samples/rust/rust_debugfs_scoped.rs
@@ -6,9 +6,9 @@
 //! `Scope::dir` to create a variety of files without the need to separately
 //! track them all.
 
-use core::sync::atomic::AtomicUsize;
 use kernel::debugfs::{Dir, Scope};
 use kernel::prelude::*;
+use kernel::sync::atomic::Atomic;
 use kernel::sync::Mutex;
 use kernel::{c_str, new_mutex, str::CString};
 
@@ -62,7 +62,7 @@ fn create_file_write(
     let file_name = CString::try_from_fmt(fmt!("{name_str}"))?;
     for sub in items {
         nums.push(
-            AtomicUsize::new(sub.parse().map_err(|_| EINVAL)?),
+            Atomic::<usize>::new(sub.parse().map_err(|_| EINVAL)?),
             GFP_KERNEL,
         )?;
     }
@@ -109,7 +109,7 @@ impl ModuleData {
 
 struct DeviceData {
     name: CString,
-    nums: KVec<AtomicUsize>,
+    nums: KVec<Atomic<usize>>,
 }
 
 fn init_control(base_dir: &Dir, dyn_dirs: Dir) -> impl PinInit<Scope<ModuleData>> + '_ {