[PATCH v3 00/11] rust: use `core::ffi::CStr` method names

[Tamir Duberstein]

This is series 2b/5 of the migration to `core::ffi::CStr`[0].
20250704-core-cstr-pre...@gmail.com.

This series depends on the prior series[0] and is intended to go through
the rust tree to reduce the number of release cycles required to
complete the work.

Subsystem maintainers: I would appreciate your `Acked-by`s so that this
can be taken through Miguel's tree (where the other series must go).

[0] https://lore.kernel.org/all/20250704-core-cstr-pre...@gmail.com/

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---
Changes in v3:
- Add a patch to deal with new code in acpi.
- Drop incorrectly applied Acked-by tags from Danilo.
- Link to v2: https://lore.kernel.org/r/20250719-core-cstr-fan...@gmail.com

Changes in v2:
- Update patch title (was nova-core, now drm/panic).
- Link to v1: https://lore.kernel.org/r/20250709-core-cstr-fan...@gmail.com

---
Tamir Duberstein (11):
drm/panic: use `core::ffi::CStr` method names
rust: auxiliary: use `core::ffi::CStr` method names
rust: configfs: use `core::ffi::CStr` method names
rust: cpufreq: use `core::ffi::CStr` method names
rust: drm: use `core::ffi::CStr` method names
rust: firmware: use `core::ffi::CStr` method names
rust: kunit: use `core::ffi::CStr` method names
rust: miscdevice: use `core::ffi::CStr` method names
rust: net: use `core::ffi::CStr` method names
rust: of: use `core::ffi::CStr` method names
rust: acpi: use `core::ffi::CStr` method names

drivers/gpu/drm/drm_panic_qr.rs | 2 +-
rust/kernel/acpi.rs | 7 ++-----
rust/kernel/auxiliary.rs | 4 ++--
rust/kernel/configfs.rs | 4 ++--
rust/kernel/cpufreq.rs | 2 +-
rust/kernel/drm/device.rs | 4 ++--
rust/kernel/firmware.rs | 2 +-
rust/kernel/kunit.rs | 6 +++---
rust/kernel/miscdevice.rs | 2 +-
rust/kernel/net/phy.rs | 2 +-
rust/kernel/of.rs | 2 +-
samples/rust/rust_configfs.rs | 2 +-
12 files changed, 18 insertions(+), 21 deletions(-)
---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250709-core-cstr-fanout-1-f20611832272

Best regards,
--
Tamir Duberstein <tam...@gmail.com>

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>
Acked-by: Danilo Krummrich <da...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

drivers/gpu/drm/drm_panic_qr.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs
index 09a9b452e8b7..10bc5bb16992 100644
--- a/drivers/gpu/drm/drm_panic_qr.rs
+++ b/drivers/gpu/drm/drm_panic_qr.rs
@@ -948,7 +948,7 @@ fn draw_all(&mut self, data: impl Iterator<Item = u8>) {
// nul-terminated string.
let url_cstr: &CStr = unsafe { CStr::from_char_ptr(url) };
let segments = &[
- &Segment::Binary(url_cstr.as_bytes()),
+ &Segment::Binary(url_cstr.to_bytes()),
&Segment::Numeric(&data_slice[0..data_len]),
];
match EncodedMsg::new(segments, tmp_slice) {

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>
Acked-by: Danilo Krummrich <da...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/auxiliary.rs | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index 4749fb6bffef..58be09871397 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -105,8 +105,8 @@ macro_rules! module_auxiliary_driver {
impl DeviceId {
/// Create a new [`DeviceId`] from name.
pub const fn new(modname: &'static CStr, name: &'static CStr) -> Self {
- let name = name.as_bytes_with_nul();
- let modname = modname.as_bytes_with_nul();
+ let name = name.to_bytes_with_nul();
+ let modname = modname.to_bytes_with_nul();

// TODO: Replace with `bindings::auxiliary_device_id::default()` once stabilized for
// `const`.

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Also avoid `Deref<Target=BStr> for CStr` as that impl doesn't exist on
`core::ffi::CStr`.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
Acked-by: Andreas Hindborg <a.hin...@kernel.org>
---
rust/kernel/configfs.rs | 4 ++--
samples/rust/rust_configfs.rs | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/rust/kernel/configfs.rs b/rust/kernel/configfs.rs
index 2736b798cdc6..9fb5ef825e41 100644
--- a/rust/kernel/configfs.rs
+++ b/rust/kernel/configfs.rs
@@ -263,7 +263,7 @@ pub fn new(
try_pin_init!(Self {
group <- pin_init::init_zeroed().chain(|v: &mut Opaque<bindings::config_group>| {
let place = v.get();
- let name = name.as_bytes_with_nul().as_ptr();
+ let name = name.to_bytes_with_nul().as_ptr();
// SAFETY: It is safe to initialize a group once it has been zeroed.
unsafe {
bindings::config_group_init_type_name(place, name.cast(), item_type.as_ptr())
@@ -613,7 +613,7 @@ impl<const ID: u64, O, Data> Attribute<ID, O, Data>
pub const fn new(name: &'static CStr) -> Self {
Self {
attribute: Opaque::new(bindings::configfs_attribute {
- ca_name: name.as_char_ptr(),
+ ca_name: crate::str::as_char_ptr_in_const_context(name),
ca_owner: core::ptr::null_mut(),
ca_mode: 0o660,
show: Some(Self::show),
diff --git a/samples/rust/rust_configfs.rs b/samples/rust/rust_configfs.rs
index af04bfa35cb2..5005453f874d 100644
--- a/samples/rust/rust_configfs.rs
+++ b/samples/rust/rust_configfs.rs
@@ -94,7 +94,7 @@ impl configfs::AttributeOperations<0> for Configuration {

fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
pr_info!("Show message\n");
- let data = container.message;
+ let data = container.message.to_bytes();
page[0..data.len()].copy_from_slice(data);
Ok(data.len())
}

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>
Signed-off-by: Tamir Duberstein <tam...@gmail.com>

Acked-by: Viresh Kumar <viresh...@linaro.org>
---
rust/kernel/cpufreq.rs | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index afc15e72a7c3..2bdf9ae00ffe 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -1018,7 +1018,7 @@ impl<T: Driver> Registration<T> {
};

const fn copy_name(name: &'static CStr) -> [c_char; CPUFREQ_NAME_LEN] {
- let src = name.as_bytes_with_nul();
+ let src = name.to_bytes_with_nul();
let mut dst = [0; CPUFREQ_NAME_LEN];

build_assert!(src.len() <= CPUFREQ_NAME_LEN);

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>

Acked-by: Danilo Krummrich <da...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/drm/device.rs | 4 ++--

1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
index 3bb7c83966cf..4a51909ccc76 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs
@@ -83,8 +83,8 @@ impl<T: drm::Driver> Device<T> {
major: T::INFO.major,
minor: T::INFO.minor,
patchlevel: T::INFO.patchlevel,
- name: T::INFO.name.as_char_ptr().cast_mut(),
- desc: T::INFO.desc.as_char_ptr().cast_mut(),
+ name: crate::str::as_char_ptr_in_const_context(T::INFO.name).cast_mut(),
+ desc: crate::str::as_char_ptr_in_const_context(T::INFO.desc).cast_mut(),

driver_features: drm::driver::FEAT_GEM,
ioctls: T::IOCTLS.as_ptr(),

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>
Acked-by: Danilo Krummrich <da...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/firmware.rs | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
index 1abab5b2f052..94e6bb88b903 100644
--- a/rust/kernel/firmware.rs
+++ b/rust/kernel/firmware.rs
@@ -291,7 +291,7 @@ const fn push_module_name(self) -> Self {
let module_name = this.module_name;

if !this.module_name.is_empty() {
- this = this.push_internal(module_name.as_bytes_with_nul());
+ this = this.push_internal(module_name.to_bytes_with_nul());

if N != 0 {
// Re-use the space taken by the NULL terminator and swap it with the '.' separator.

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/kunit.rs | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index 41efd87595d6..5866cff072f9 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -102,12 +102,12 @@ unsafe impl Sync for Location {}
unsafe impl Sync for UnaryAssert {}

static LOCATION: Location = Location($crate::bindings::kunit_loc {
- file: FILE.as_char_ptr(),
+ file: $crate::str::as_char_ptr_in_const_context(FILE),
line: LINE,
});
static ASSERTION: UnaryAssert = UnaryAssert($crate::bindings::kunit_unary_assert {
assert: $crate::bindings::kunit_assert {},
- condition: CONDITION.as_char_ptr(),
+ condition: $crate::str::as_char_ptr_in_const_context(CONDITION),
expected_true: true,
});

@@ -202,7 +202,7 @@ pub const fn kunit_case(
) -> kernel::bindings::kunit_case {
kernel::bindings::kunit_case {
run_case: Some(run_case),
- name: name.as_char_ptr(),
+ name: kernel::str::as_char_ptr_in_const_context(name),
attr: kernel::bindings::kunit_attributes {
speed: kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL,
},

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/miscdevice.rs | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index 6373fe183b27..d3aa7d25afad 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -34,7 +34,7 @@ pub const fn into_raw<T: MiscDevice>(self) -> bindings::miscdevice {
// SAFETY: All zeros is valid for this C type.
let mut result: bindings::miscdevice = unsafe { MaybeUninit::zeroed().assume_init() };
result.minor = bindings::MISC_DYNAMIC_MINOR as ffi::c_int;
- result.name = self.name.as_char_ptr();
+ result.name = crate::str::as_char_ptr_in_const_context(self.name);
result.fops = MiscdeviceVTable::<T>::build();
result
}

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/net/phy.rs | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs
index 7de5cc7a0eee..be1027b7961b 100644
--- a/rust/kernel/net/phy.rs
+++ b/rust/kernel/net/phy.rs
@@ -497,7 +497,7 @@ unsafe impl Sync for DriverVTable {}
pub const fn create_phy_driver<T: Driver>() -> DriverVTable {
// INVARIANT: All the fields of `struct phy_driver` are initialized properly.
DriverVTable(Opaque::new(bindings::phy_driver {
- name: T::NAME.as_char_ptr().cast_mut(),
+ name: crate::str::as_char_ptr_in_const_context(T::NAME).cast_mut(),
flags: T::FLAGS,
phy_id: T::PHY_DEVICE_ID.id(),
phy_id_mask: T::PHY_DEVICE_ID.mask_as_int(),

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: https://github.com/Rust-for-Linux/linux/issues/1075
Acked-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Alice Ryhl <alic...@google.com>
Reviewed-by: Benno Lossin <los...@kernel.org>

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/of.rs | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs
index b76b35265df2..58b20c367f99 100644
--- a/rust/kernel/of.rs
+++ b/rust/kernel/of.rs
@@ -34,7 +34,7 @@ fn index(&self) -> usize {
impl DeviceId {
/// Create a new device id from an OF 'compatible' string.
pub const fn new(compatible: &'static CStr) -> Self {
- let src = compatible.as_bytes_with_nul();
+ let src = compatible.to_bytes_with_nul();
// Replace with `bindings::of_device_id::default()` once stabilized for `const`.
// SAFETY: FFI type is valid to be zero-initialized.
let mut of: bindings::of_device_id = unsafe { core::mem::zeroed() };

--
2.50.1

[Tamir Duberstein]

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Signed-off-by: Tamir Duberstein <tam...@gmail.com>
---

rust/kernel/acpi.rs | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/rust/kernel/acpi.rs b/rust/kernel/acpi.rs
index 7ae317368b00..37e1161c1298 100644
--- a/rust/kernel/acpi.rs
+++ b/rust/kernel/acpi.rs
@@ -37,11 +37,8 @@ impl DeviceId {
/// Create a new device id from an ACPI 'id' string.
#[inline(always)]
pub const fn new(id: &'static CStr) -> Self {
- build_assert!(
- id.len_with_nul() <= Self::ACPI_ID_LEN,
- "ID exceeds 16 bytes"
- );
- let src = id.as_bytes_with_nul();
+ let src = id.to_bytes_with_nul();
+ build_assert!(src.len() <= Self::ACPI_ID_LEN, "ID exceeds 16 bytes");
// Replace with `bindings::acpi_device_id::default()` once stabilized for `const`.

// SAFETY: FFI type is valid to be zero-initialized.

let mut acpi: bindings::acpi_device_id = unsafe { core::mem::zeroed() };

--
2.50.1

[Jocelyn Falempe]

On 13/08/2025 17:41, Tamir Duberstein wrote:
> Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
> avoid methods that only exist on the latter.

Thanks, it looks good to me.

Acked-by: Jocelyn Falempe <jfal...@redhat.com>

[Benno Lossin]

On Wed Aug 13, 2025 at 5:42 PM CEST, Tamir Duberstein wrote:
> Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
> avoid methods that only exist on the latter.
>
> Signed-off-by: Tamir Duberstein <tam...@gmail.com>

Reviewed-by: Benno Lossin <los...@kernel.org>

---
Cheers,
Benno

[Miguel Ojeda]

On Wed, Aug 13, 2025 at 5:42 PM Tamir Duberstein <tam...@gmail.com> wrote:
>
> This is series 2b/5 of the migration to `core::ffi::CStr`[0].
> 20250704-core-cstr-pre...@gmail.com.
>
> This series depends on the prior series[0] and is intended to go through
> the rust tree to reduce the number of release cycles required to
> complete the work.
>
> Subsystem maintainers: I would appreciate your `Acked-by`s so that this
> can be taken through Miguel's tree (where the other series must go).
>
> [0] https://lore.kernel.org/all/20250704-core-cstr-pre...@gmail.com/
>
> Signed-off-by: Tamir Duberstein <tam...@gmail.com>

Applied to `rust-next` -- thanks everyone!

If any maintainer has a problem with this, please shout.

Cheers,
Miguel