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rust: debugfs: drop 'static bound from ScopedDir file creation methods

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Drop the T: 'static bound from ScopedDir's file creation methods
(read_binary_file(), read_only_file(), etc.) to support registering
debugfs files backed by types that contain non-'static references, such
as dma::Coherent<'a, T>.

The previous 'static bound existed because ScopedDir::create_file() took
&'static FileOps<T>, and &'static requires T: 'static for well-
formedness. However, this was overly conservative: the file_operations
pointer passed to the C debugfs API just needs to be 'static, not the
entire FileOps<T>.

Store &'static bindings::file_operations in FileOps<T> instead of the
file_operations by value. In each trait impl, take a reference to the
file_operations struct within the const block; since
bindings::file_operations does not mention T, the reference is promoted
to 'static regardless of T's lifetime parameters.

Replace the Deref impl with an explicit fops() method that returns the
stored &'static reference.

Link: https://lore.kernel.org/driver-core/20260830193824.471089-2-dakr@kernel.org
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260830193824.471089-2-dakr@kernel.org
[ Remove unrelated change from Self to T. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Danilo Krummrich 2026-08-29 14:42:54 +02:00
parent cee9395acd
commit 9dc6cedcd9
3 changed files with 22 additions and 37 deletions
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26
rust/kernel/debugfs.rs
View File

@ -538,7 +538,7 @@ pub fn dir<'dir2>(&'dir2 self, name: &CStr) -> ScopedDir<'data, 'dir2> {
}
}
fn create_file<T: Sync>(&self, name: &CStr, data: &'data T, vtable: &'static FileOps<T>) {
fn create_file<T: Sync>(&self, name: &CStr, data: &'data T, vtable: &FileOps<T>) {
#[cfg(CONFIG_DEBUG_FS)]
core::mem::forget(Entry::file(name, &self.entry, data, vtable));
}
@ -550,7 +550,7 @@ fn create_file<T: Sync>(&self, name: &CStr, data: &'data T, vtable: &'static Fil
/// This function does not produce an owning handle to the file. The created
/// file is removed when the [`Scope`] that this directory belongs
/// to is dropped.
pub fn read_only_file<T: Writer + Send + Sync + 'static>(&self, name: &CStr, data: &'data T) {
pub fn read_only_file<T: Writer + Send + Sync>(&self, name: &CStr, data: &'data T) {
self.create_file(name, data, &T::FILE_OPS)
}
@ -560,11 +560,7 @@ pub fn read_only_file<T: Writer + Send + Sync + 'static>(&self, name: &CStr, dat
///
/// This function does not produce an owning handle to the file. The created file is removed
/// when the [`Scope`] that this directory belongs to is dropped.
pub fn read_binary_file<T: BinaryWriter + Send + Sync + 'static>(
&self,
name: &CStr,
data: &'data T,
) {
pub fn read_binary_file<T: BinaryWriter + Send + Sync>(&self, name: &CStr, data: &'data T) {
self.create_file(name, data, &T::FILE_OPS)
}
@ -596,11 +592,7 @@ pub fn read_callback_file<T, F>(&self, name: &CStr, data: &'data T, _f: &'static
/// This function does not produce an owning handle to the file. The created
/// file is removed when the [`Scope`] that this directory belongs
/// to is dropped.
pub fn read_write_file<T: Writer + Reader + Send + Sync + 'static>(
&self,
name: &CStr,
data: &'data T,
) {
pub fn read_write_file<T: Writer + Reader + Send + Sync>(&self, name: &CStr, data: &'data T) {
let vtable = &<T as ReadWriteFile<_>>::FILE_OPS;
self.create_file(name, data, vtable)
}
@ -612,7 +604,7 @@ pub fn read_write_file<T: Writer + Reader + Send + Sync + 'static>(
///
/// This function does not produce an owning handle to the file. The created file is removed
/// when the [`Scope`] that this directory belongs to is dropped.
pub fn read_write_binary_file<T: BinaryWriter + BinaryReader + Send + Sync + 'static>(
pub fn read_write_binary_file<T: BinaryWriter + BinaryReader + Send + Sync>(
&self,
name: &CStr,
data: &'data T,
@ -655,7 +647,7 @@ pub fn read_write_callback_file<T, F, W>(
/// This function does not produce an owning handle to the file. The created
/// file is removed when the [`Scope`] that this directory belongs
/// to is dropped.
pub fn write_only_file<T: Reader + Send + Sync + 'static>(&self, name: &CStr, data: &'data T) {
pub fn write_only_file<T: Reader + Send + Sync>(&self, name: &CStr, data: &'data T) {
let vtable = &<T as WriteFile<_>>::FILE_OPS;
self.create_file(name, data, vtable)
}
@ -666,11 +658,7 @@ pub fn write_only_file<T: Reader + Send + Sync + 'static>(&self, name: &CStr, da
///
/// This function does not produce an owning handle to the file. The created file is removed
/// when the [`Scope`] that this directory belongs to is dropped.
pub fn write_binary_file<T: BinaryReader + Send + Sync + 'static>(
&self,
name: &CStr,
data: &'data T,
) {
pub fn write_binary_file<T: BinaryReader + Send + Sync>(&self, name: &CStr, data: &'data T) {
self.create_file(name, data, &T::FILE_OPS)
}

4
rust/kernel/debugfs/entry.rs
View File

@ -74,7 +74,7 @@ pub(crate) unsafe fn dynamic_file<T>(
parent.as_ptr(),
core::ptr::from_ref(data) as *mut c_void,
core::ptr::null(),
&**file_ops,
file_ops.fops(),
)
};
@ -127,7 +127,7 @@ pub(crate) fn file<T>(
parent.as_ptr(),
core::ptr::from_ref(data) as *mut c_void,
core::ptr::null(),
&**file_ops,
file_ops.fops(),
)
};

29
rust/kernel/debugfs/file_ops.rs
View File

@ -20,9 +20,6 @@
use core::marker::PhantomData;
#[cfg(CONFIG_DEBUG_FS)]
use core::ops::Deref;
/// # Invariant
///
/// `FileOps<T>` will always contain an `operations` which is safe to use for a file backed
@ -30,7 +27,7 @@
/// into a reference.
pub(super) struct FileOps<T> {
#[cfg(CONFIG_DEBUG_FS)]
operations: bindings::file_operations,
operations: &'static bindings::file_operations,
#[cfg(CONFIG_DEBUG_FS)]
mode: u16,
_phantom: PhantomData<T>,
@ -41,7 +38,7 @@ impl<T> FileOps<T> {
///
/// The caller asserts that the provided `operations` is safe to use for a file whose
/// inode has a pointer to `T` in its private data that is safe to convert into a reference.
const unsafe fn new(operations: bindings::file_operations, mode: u16) -> Self {
const unsafe fn new(operations: &'static bindings::file_operations, mode: u16) -> Self {
Self {
#[cfg(CONFIG_DEBUG_FS)]
operations,
@ -65,11 +62,11 @@ pub(super) const fn adapt(&self) -> &FileOps<T::Inner> {
}
#[cfg(CONFIG_DEBUG_FS)]
impl<T> Deref for FileOps<T> {
type Target = bindings::file_operations;
fn deref(&self) -> &Self::Target {
&self.operations
impl<T> FileOps<T> {
/// Returns a `'static` reference to the inner `file_operations`.
#[inline]
pub(crate) fn fops(&self) -> &'static bindings::file_operations {
self.operations
}
}
@ -130,7 +127,7 @@ pub(crate) trait ReadFile<T> {
impl<T: Writer + Sync> ReadFile<T> for T {
const FILE_OPS: FileOps<T> = {
let operations = bindings::file_operations {
let operations = &bindings::file_operations {
read: Some(bindings::seq_read),
llseek: Some(bindings::seq_lseek),
release: Some(bindings::single_release),
@ -181,7 +178,7 @@ pub(crate) trait ReadWriteFile<T> {
impl<T: Writer + Reader + Sync> ReadWriteFile<T> for T {
const FILE_OPS: FileOps<T> = {
let operations = bindings::file_operations {
let operations = &bindings::file_operations {
open: Some(writer_open::<T>),
read: Some(bindings::seq_read),
write: Some(write::<T>),
@ -238,7 +235,7 @@ pub(crate) trait WriteFile<T> {
impl<T: Reader + Sync> WriteFile<T> for T {
const FILE_OPS: FileOps<T> = {
let operations = bindings::file_operations {
let operations = &bindings::file_operations {
open: Some(write_only_open),
write: Some(write_only_write::<T>),
llseek: Some(bindings::noop_llseek),
@ -290,7 +287,7 @@ pub(crate) trait BinaryReadFile<T> {
impl<T: BinaryWriter + Sync> BinaryReadFile<T> for T {
const FILE_OPS: FileOps<T> = {
let operations = bindings::file_operations {
let operations = &bindings::file_operations {
read: Some(blob_read::<T>),
llseek: Some(bindings::default_llseek),
open: Some(bindings::simple_open),
@ -344,7 +341,7 @@ pub(crate) trait BinaryWriteFile<T> {
impl<T: BinaryReader + Sync> BinaryWriteFile<T> for T {
const FILE_OPS: FileOps<T> = {
let operations = bindings::file_operations {
let operations = &bindings::file_operations {
write: Some(blob_write::<T>),
llseek: Some(bindings::default_llseek),
open: Some(bindings::simple_open),
@ -368,7 +365,7 @@ pub(crate) trait BinaryReadWriteFile<T> {
impl<T: BinaryWriter + BinaryReader + Sync> BinaryReadWriteFile<T> for T {
const FILE_OPS: FileOps<T> = {
let operations = bindings::file_operations {
let operations = &bindings::file_operations {
read: Some(blob_read::<T>),
write: Some(blob_write::<T>),
llseek: Some(bindings::default_llseek),