Re: [PATCH v17 00/11] rust: replace kernel::str::CStr w/ core::ffi::CStr

Alice Ryhl
2025-10-18T17:02:41Z

On Wed, Oct 15, 2025 at 03:24:30PM -0400, Tamir Duberstein wrote:
> This picks up from Michal Rostecki's work[0]. Per Michal's guidance I
> have omitted Co-authored tags, as the end result is quite different.
>
> This series is intended to be taken through rust-next. The final patch
> in the series requires some other subsystems' `Acked-by`s:
> - drivers/android/binder/stats.rs: rust_binder. Alice, could you take a
> look?
> - rust/kernel/device.rs: driver-core. Already acked by gregkh.
> - rust/kernel/firmware.rs: driver-core. Danilo, could you take a look?
> - rust/kernel/seq_file.rs: vfs. Christian, could you take a look?
> - rust/kernel/sync/*: locking-core. Boqun, could you take a look?
>
> Link: https://lore.kernel.org/rust-for-linux/20240819153656.28807-2-vadorovsky@protonmail.com/t/#u [0]
> Closes: https://github.com/Rust-for-Linux/linux/issues/1075
>
> Signed-off-by: Tamir Duberstein <tamird@gmail.com>

You need a few more changes:

diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs
index 1e6c8c42fb3a..c1cfaeaa36a2 100644
--- a/rust/kernel/clk.rs
+++ b/rust/kernel/clk.rs
@@ -136,7 +136,7 @@ impl Clk {
///
/// [`clk_get`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_get
pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
- let con_id = name.map_or(ptr::null(), |n| n.as_ptr());
+ let con_id = name.map_or(ptr::null(), |n| n.as_char_ptr());

// SAFETY: It is safe to call [`clk_get`] for a valid device pointer.
//
@@ -304,7 +304,7 @@ impl OptionalClk {
/// [`clk_get_optional`]:
/// https://docs.kernel.org/core-api/kernel-api.html#c.clk_get_optional
pub fn get(dev: &Device, name: Option<&CStr>) -> Result<Self> {
- let con_id = name.map_or(ptr::null(), |n| n.as_ptr());
+ let con_id = name.map_or(ptr::null(), |n| n.as_char_ptr());

// SAFETY: It is safe to call [`clk_get_optional`] for a valid device pointer.
//
diff --git a/rust/kernel/configfs.rs b/rust/kernel/configfs.rs
index 10f1547ca9f1..466fb7f40762 100644
--- a/rust/kernel/configfs.rs
+++ b/rust/kernel/configfs.rs
@@ -157,7 +157,7 @@ pub fn new(
unsafe {
bindings::config_group_init_type_name(
&mut (*place.get()).su_group,
- name.as_ptr(),
+ name.as_char_ptr(),
item_type.as_ptr(),
)
};
diff --git a/rust/kernel/debugfs/entry.rs b/rust/kernel/debugfs/entry.rs
index f99402cd3ba0..5de0ebc27198 100644
--- a/rust/kernel/debugfs/entry.rs
+++ b/rust/kernel/debugfs/entry.rs
@@ -2,8 +2,7 @@
// Copyright (C) 2025 Google LLC.

use crate::debugfs::file_ops::FileOps;
-use crate::ffi::c_void;
-use crate::str::CStr;
+use crate::prelude::*;
use crate::sync::Arc;
use core::marker::PhantomData;

diff --git a/rust/kernel/regulator.rs b/rust/kernel/regulator.rs
index b55a201e5029..65a4eb096cae 100644
--- a/rust/kernel/regulator.rs
+++ b/rust/kernel/regulator.rs
@@ -84,7 +84,7 @@ pub struct Error<State: RegulatorState> {
pub fn devm_enable(dev: &Device<Bound>, name: &CStr) -> Result {
// SAFETY: `dev` is a valid and bound device, while `name` is a valid C
// string.
- to_result(unsafe { bindings::devm_regulator_get_enable(dev.as_raw(), name.as_ptr()) })
+ to_result(unsafe { bindings::devm_regulator_get_enable(dev.as_raw(), name.as_char_ptr()) })
}

/// Same as [`devm_enable`], but calls `devm_regulator_get_enable_optional`
@@ -102,7 +102,9 @@ pub fn devm_enable(dev: &Device<Bound>, name: &CStr) -> Result {
pub fn devm_enable_optional(dev: &Device<Bound>, name: &CStr) -> Result {
// SAFETY: `dev` is a valid and bound device, while `name` is a valid C
// string.
- to_result(unsafe { bindings::devm_regulator_get_enable_optional(dev.as_raw(), name.as_ptr()) })
+ to_result(unsafe {
+ bindings::devm_regulator_get_enable_optional(dev.as_raw(), name.as_char_ptr())
+ })
}

/// A `struct regulator` abstraction.
@@ -268,7 +270,8 @@ pub fn get_voltage(&self) -> Result<Voltage> {
fn get_internal(dev: &Device, name: &CStr) -> Result<Regulator<T>> {
// SAFETY: It is safe to call `regulator_get()`, on a device pointer
// received from the C code.
- let inner = from_err_ptr(unsafe { bindings::regulator_get(dev.as_raw(), name.as_ptr()) })?;
+ let inner =
+ from_err_ptr(unsafe { bindings::regulator_get(dev.as_raw(), name.as_char_ptr()) })?;

// SAFETY: We can safely trust `inner` to be a pointer to a valid
// regulator if `ERR_PTR` was not returned.
--