[PATCH v10 5/5] rust: remove core::ffi::CStr reexport

Tamir Duberstein
Sat, 24 May 2025 20:33:35 -0000

Clean up references to `kernel::str::CStr`.

Signed-off-by: Tamir Duberstein <tamird at gmail.com>
---
 drivers/gpu/drm/drm_panic_qr.rs   |  3 ++-
 drivers/gpu/nova-core/firmware.rs |  2 +-
 drivers/net/phy/ax88796b_rust.rs  |  1 +
 drivers/net/phy/qt2025.rs         |  1 +
 rust/kernel/device.rs             |  3 +--
 rust/kernel/driver.rs             |  4 ++--
 rust/kernel/error.rs              |  6 ++----
 rust/kernel/faux.rs               |  5 ++++-
 rust/kernel/firmware.rs           | 15 ++++-----------
 rust/kernel/kunit.rs              |  6 +++---
 rust/kernel/lib.rs                |  2 +-
 rust/kernel/miscdevice.rs         |  3 +--
 rust/kernel/net/phy.rs            |  4 +++-
 rust/kernel/of.rs                 |  3 ++-
 rust/kernel/pci.rs                |  2 +-
 rust/kernel/platform.rs           |  2 +-
 rust/kernel/prelude.rs            |  5 +----
 rust/kernel/str.rs                | 22 ++++++++++------------
 rust/kernel/sync/condvar.rs       |  4 ++--
 rust/kernel/sync/lock.rs          |  4 ++--
 rust/kernel/sync/lock/global.rs   |  5 +++--
 rust/kernel/sync/poll.rs          |  1 +
 rust/kernel/workqueue.rs          |  1 +
 rust/macros/module.rs             |  2 +-
 24 files changed, 51 insertions(+), 55 deletions(-)

diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs
index d8192a9bef63..ba63238d352f 100644
--- a/drivers/gpu/drm/drm_panic_qr.rs
+++ b/drivers/gpu/drm/drm_panic_qr.rs
@@ -27,7 +27,8 @@
 //! * <https://github.com/erwanvivien/fast_qr>
 //! * <https://github.com/bjguillot/qr>

-use kernel::{prelude::*, str::CStr};
+use core::ffi::CStr;
+use kernel::prelude::*;

 #[derive(Debug, Clone, Copy, PartialEq, Eq, Ord, PartialOrd)]
 struct Version(usize);
diff --git a/drivers/gpu/nova-core/firmware.rs
b/drivers/gpu/nova-core/firmware.rs
index 6e6361c59ca1..0af1f0df2fa5 100644
--- a/drivers/gpu/nova-core/firmware.rs
+++ b/drivers/gpu/nova-core/firmware.rs
@@ -30,7 +30,7 @@ const fn make_entry_chipset(self, chipset: &str) ->
Self {
     }

     pub(crate) const fn create(
-        module_name: &'static kernel::str::CStr,
+        module_name: &'static core::ffi::CStr,
     ) -> firmware::ModInfoBuilder<N> {
         let mut this = Self(firmware::ModInfoBuilder::new(module_name));
         let mut i = 0;
diff --git a/drivers/net/phy/ax88796b_rust.rs b/drivers/net/phy/ax88796b_rust.rs
index 2d24628a4e58..68b8e30ae296 100644
--- a/drivers/net/phy/ax88796b_rust.rs
+++ b/drivers/net/phy/ax88796b_rust.rs
@@ -4,6 +4,7 @@
 //! Rust Asix PHYs driver
 //!
 //! C version of this driver: [`drivers/net/phy/ax88796b.c`](./ax88796b.c)
+use core::ffi::CStr;
 use kernel::{
     net::phy::{self, reg::C22, DeviceId, Driver},
     prelude::*,
diff --git a/drivers/net/phy/qt2025.rs b/drivers/net/phy/qt2025.rs
index 9ccc75f70219..78ce2866f2b6 100644
--- a/drivers/net/phy/qt2025.rs
+++ b/drivers/net/phy/qt2025.rs
@@ -9,6 +9,7 @@
 //!
 //! The QT2025 PHY integrates an Intel 8051 micro-controller.

+use core::ffi::CStr;
 use kernel::error::code;
 use kernel::firmware::Firmware;
 use kernel::net::phy::{
diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 9074322c79e8..2cf5903f7dde 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -6,10 +6,9 @@

 use crate::{
     bindings,
-    str::CStr,
     types::{ARef, Opaque},
 };
-use core::{fmt, ptr};
+use core::{ffi::CStr, fmt, ptr};

 #[cfg(CONFIG_PRINTK)]
 use crate::str::CStrExt as _;
diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index ec9166cedfa7..9926664d9ba2 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -6,8 +6,8 @@
 //! register using the [`Registration`] class.

 use crate::error::{Error, Result};
-use crate::{device, of, str::CStr, try_pin_init, types::Opaque, ThisModule};
-use core::pin::Pin;
+use crate::{device, of, try_pin_init, types::Opaque, ThisModule};
+use core::{ffi::CStr, pin::Pin};
 use pin_init::{pin_data, pinned_drop, PinInit};

 /// The [`RegistrationOps`] trait serves as generic interface for subsystems
(e.g., PCI, Platform,
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 933c048c04f1..b2b46d26f7b7 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -4,11 +4,9 @@
 //!
 //! C header:
[`include/uapi/asm-generic/errno-base.h`](srctree/include/uapi/asm-generic/errno-base.h)

-use crate::{
-    alloc::{layout::LayoutError, AllocError},
-    str::CStr,
-};
+use crate::alloc::{layout::LayoutError, AllocError};

+use core::ffi::CStr;
 use core::fmt;
 use core::num::NonZeroI32;
 use core::num::TryFromIntError;
diff --git a/rust/kernel/faux.rs b/rust/kernel/faux.rs
index 8a50fcd4c9bb..d9e5cd265101 100644
--- a/rust/kernel/faux.rs
+++ b/rust/kernel/faux.rs
@@ -7,7 +7,10 @@
 //! C header: [`include/linux/device/faux.h`]

 use crate::{bindings, device, error::code::*, prelude::*};
-use core::ptr::{addr_of_mut, null, null_mut, NonNull};
+use core::{
+    ffi::CStr,
+    ptr::{addr_of_mut, null, null_mut, NonNull},
+};

 /// The registration of a faux device.
 ///
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
index 09fd3a27bcf0..4ba5e5589d7b 100644
--- a/rust/kernel/firmware.rs
+++ b/rust/kernel/firmware.rs
@@ -4,15 +4,8 @@
 //!
 //! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h)

-use crate::{
-    bindings,
-    device::Device,
-    error::Error,
-    error::Result,
-    ffi,
-    str::{CStr, CStrExt as _},
-};
-use core::ptr::NonNull;
+use crate::{bindings, device::Device, error::Error, error::Result, ffi,
str::CStrExt as _};
+use core::{ffi::CStr, ptr::NonNull};

 /// # Invariants
 ///
@@ -168,7 +161,7 @@ unsafe impl Sync for Firmware {}
 ///     const DIR: &'static str = "vendor/chip/";
 ///     const FILES: [&'static str; 3] = [ "foo",
"bar", "baz" ];
 ///
-///     const fn create(module_name: &'static kernel::str::CStr) ->
firmware::ModInfoBuilder<N> {
+///     const fn create(module_name: &'static core::ffi::CStr) ->
firmware::ModInfoBuilder<N> {
 ///         let mut builder = firmware::ModInfoBuilder::new(module_name);
 ///
 ///         let mut i = 0;
@@ -202,7 +195,7 @@ macro_rules! module_firmware {
     // this macro. Hence, we can neither use `expr` nor `ty`.
     ($($builder:tt)*) => {
         const _: () = {
-            const __MODULE_FIRMWARE_PREFIX: &'static $crate::str::CStr
= if cfg!(MODULE) {
+            const __MODULE_FIRMWARE_PREFIX: &'static ::core::ffi::CStr
= if cfg!(MODULE) {
                 c""
             } else {
                 <LocalModule as $crate::ModuleMetadata>::NAME
diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index 09148e982f48..83b48e2f8379 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -58,9 +58,9 @@ macro_rules! kunit_assert {
                 break 'out;
             }

-            static FILE: &'static $crate::str::CStr =
$crate::c_str_avoid_literals!($file);
+            static FILE: &'static core::ffi::CStr =
$crate::c_str_avoid_literals!($file);
             static LINE: i32 = core::line!() as i32 - $diff;
-            static CONDITION: &'static $crate::str::CStr +
static CONDITION: &'static core::ffi::CStr
$crate::c_str_avoid_literals!(stringify!($condition));

             // SAFETY: FFI call without safety requirements.
@@ -171,7 +171,7 @@ macro_rules! kunit_assert_eq {
 /// Use [`kunit_case_null`] to generate such a delimiter.
 #[doc(hidden)]
 pub const fn kunit_case(
-    name: &'static kernel::str::CStr,
+    name: &'static core::ffi::CStr,
     run_case: unsafe extern "C" fn(*mut kernel::bindings::kunit),
 ) -> kernel::bindings::kunit_case {
     kernel::bindings::kunit_case {
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index ec48c818d512..d36b123c518b 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -152,7 +152,7 @@ fn init(module: &'static ThisModule) -> impl
pin_init::PinInit<Self, error::Erro
 /// Metadata attached to a [`Module`] or [`InPlaceModule`].
 pub trait ModuleMetadata {
     /// The name of the module as specified in the `module!` macro.
-    const NAME: &'static crate::str::CStr;
+    const NAME: &'static core::ffi::CStr;
 }

 /// Equivalent to `THIS_MODULE` in the C API.
diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index d684ec4ef4d0..47f718a9ceb5 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -16,10 +16,9 @@
     fs::File,
     prelude::*,
     seq_file::SeqFile,
-    str::CStr,
     types::{ForeignOwnable, Opaque},
 };
-use core::{marker::PhantomData, mem::MaybeUninit, pin::Pin};
+use core::{ffi::CStr, marker::PhantomData, mem::MaybeUninit, pin::Pin};

 /// Options for creating a misc device.
 #[derive(Copy, Clone)]
diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs
index 8129419a3931..72635af8f20e 100644
--- a/rust/kernel/net/phy.rs
+++ b/rust/kernel/net/phy.rs
@@ -7,7 +7,7 @@
 //! C headers: [`include/linux/phy.h`](srctree/include/linux/phy.h).

 use crate::{error::*, prelude::*, types::Opaque};
-use core::{marker::PhantomData, ptr::addr_of_mut};
+use core::{ffi::CStr, marker::PhantomData, ptr::addr_of_mut};

 pub mod reg;

@@ -780,6 +780,7 @@ const fn as_int(&self) -> u32 {
 ///
 /// ```
 /// # mod module_phy_driver_sample {
+/// use core::ffi::CStr;
 /// use kernel::net::phy::{self, DeviceId};
 /// use kernel::prelude::*;
 ///
@@ -807,6 +808,7 @@ const fn as_int(&self) -> u32 {
 /// This expands to the following code:
 ///
 /// ```ignore
+/// use core::ffi::CStr;
 /// use kernel::net::phy::{self, DeviceId};
 /// use kernel::prelude::*;
 ///
diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs
index 12ea65df46de..087ac8e05551 100644
--- a/rust/kernel/of.rs
+++ b/rust/kernel/of.rs
@@ -2,7 +2,8 @@

 //! Device Tree / Open Firmware abstractions.

-use crate::{bindings, device_id::RawDeviceId, prelude::*};
+use crate::{bindings, device_id::RawDeviceId};
+use core::ffi::CStr;

 /// IdTable type for OF drivers.
 pub type IdTable<T> = &'static dyn
kernel::device_id::IdTable<DeviceId, T>;
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index 3aeb1250c27f..b639e6a1f590 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -13,11 +13,11 @@
     error::{to_result, Result},
     io::Io,
     io::IoRaw,
-    str::CStr,
     types::{ARef, ForeignOwnable, Opaque},
     ThisModule,
 };
 use core::{
+    ffi::CStr,
     marker::PhantomData,
     ops::Deref,
     ptr::{addr_of_mut, NonNull},
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 7163fc468b32..ba580a4e3416 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -9,12 +9,12 @@
     error::{to_result, Result},
     of,
     prelude::*,
-    str::CStr,
     types::{ARef, ForeignOwnable, Opaque},
     ThisModule,
 };

 use core::{
+    ffi::CStr,
     marker::PhantomData,
     ops::Deref,
     ptr::{addr_of_mut, NonNull},
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index 97e8bcf73669..5d55e274b41e 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -35,10 +35,7 @@

 pub use super::error::{code::*, Error, Result};

-pub use super::{
-    str::{CStr, CStrExt as _},
-    ThisModule,
-};
+pub use super::{str::CStrExt as _, ThisModule};

 pub use super::init::InPlaceInit;

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 0385d927fcd5..cf0402d1daac 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -3,6 +3,7 @@
 //! String representations.

 use crate::alloc::{flags::*, AllocError, KVec};
+use core::ffi::CStr;
 use core::fmt::{self, Write};
 use core::ops::{Deref, DerefMut, Index};

@@ -175,8 +176,6 @@ macro_rules! b_str {
     }};
 }

-pub use core::ffi::CStr;
-
 /// Returns a C pointer to the string.
 // It is a free function rather than a method on an extension trait because:
 //
@@ -267,7 +266,6 @@ impl fmt::Display for crate::fmt::Adapter<&CStr> {
     ///
     /// ```
     /// # use kernel::prelude::fmt;
-    /// # use kernel::str::CStr;
     /// # use kernel::str::CString;
     /// let penguin = c"?";
     /// let s = CString::try_from_fmt(fmt!("{}", penguin))?;
@@ -377,8 +375,8 @@ fn as_ref(&self) -> &BStr {
 /// # Examples
 ///
 /// ```
+/// # use core::ffi::CStr;
 /// # use kernel::c_str_avoid_literals;
-/// # use kernel::str::CStr;
 /// const MY_CSTR: &CStr = c_str_avoid_literals!(concat!(file!(),
":", line!(), ": My CStr!"));
 /// ```
 #[macro_export]
@@ -388,14 +386,14 @@ macro_rules! c_str_avoid_literals {
     // too limiting to macro authors, so we rely on the name as a hint instead.
     ($str:expr) => {{
         const S: &'static str = concat!($str, "\0");
-        const C: &'static $crate::str::CStr -            match
$crate::str::CStr::from_bytes_with_nul(S.as_bytes()) {
-                Ok(v) => v,
-                Err(err) => {
-                    let _: core::ffi::FromBytesWithNulError = err;
-                    panic!("string contains interior NUL")
-                }
-            };
+        const C: &'static core::ffi::CStr = match
core::ffi::CStr::from_bytes_with_nul(S.as_bytes())
+        {
+            Ok(v) => v,
+            Err(err) => {
+                let _: core::ffi::FromBytesWithNulError = err;
+                panic!("string contains interior NUL")
+            }
+        };
         C
     }};
 }
diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index 0b6bc7f2878d..09bc35feb451 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -8,14 +8,14 @@
 use super::{lock::Backend, lock::Guard, LockClassKey};
 use crate::{
     ffi::{c_int, c_long},
-    str::{CStr, CStrExt as _},
+    str::CStrExt as _,
     task::{
         MAX_SCHEDULE_TIMEOUT, TASK_FREEZABLE, TASK_INTERRUPTIBLE, TASK_NORMAL,
TASK_UNINTERRUPTIBLE,
     },
     time::Jiffies,
     types::Opaque,
 };
-use core::{marker::PhantomPinned, pin::Pin, ptr};
+use core::{ffi::CStr, marker::PhantomPinned, pin::Pin, ptr};
 use pin_init::{pin_data, pin_init, PinInit};

 /// Creates a [`CondVar`] initialiser with the given name and a newly-created
lock class.
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index a777a22976e0..21deff0bb13b 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -7,10 +7,10 @@

 use super::LockClassKey;
 use crate::{
-    str::{CStr, CStrExt as _},
+    str::CStrExt as _,
     types::{NotThreadSafe, Opaque, ScopeGuard},
 };
-use core::{cell::UnsafeCell, marker::PhantomPinned, pin::Pin};
+use core::{cell::UnsafeCell, ffi::CStr, marker::PhantomPinned, pin::Pin};
 use pin_init::{pin_data, pin_init, PinInit};

 pub mod mutex;
diff --git a/rust/kernel/sync/lock/global.rs b/rust/kernel/sync/lock/global.rs
index 0ca23b12427c..bfeaa21ab101 100644
--- a/rust/kernel/sync/lock/global.rs
+++ b/rust/kernel/sync/lock/global.rs
@@ -5,13 +5,14 @@
 //! Support for defining statics containing locks.

 use crate::{
-    str::{CStr, CStrExt as _},
+    str::CStrExt as _,
     sync::lock::{Backend, Guard, Lock},
     sync::{LockClassKey, LockedBy},
     types::Opaque,
 };
 use core::{
     cell::UnsafeCell,
+    ffi::CStr,
     marker::{PhantomData, PhantomPinned},
     pin::Pin,
 };
@@ -267,7 +268,7 @@ macro_rules! global_lock {
         $pub enum $name {}

         impl $crate::sync::lock::GlobalLockBackend for $name {
-            const NAME: &'static $crate::str::CStr +            const
NAME: &'static core::ffi::CStr
$crate::c_str_avoid_literals!(::core::stringify!($name));
             type Item = $valuety;
             type Backend = $crate::global_lock_inner!(backend $kind);
diff --git a/rust/kernel/sync/poll.rs b/rust/kernel/sync/poll.rs
index d7e6e59e124b..bf2fb24d04ea 100644
--- a/rust/kernel/sync/poll.rs
+++ b/rust/kernel/sync/poll.rs
@@ -11,6 +11,7 @@
     sync::{CondVar, LockClassKey},
     types::Opaque,
 };
+use core::ffi::CStr;
 use core::ops::Deref;

 /// Creates a [`PollCondVar`] initialiser with the given name and a
newly-created lock class.
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index f98bd02b838f..c64769ef5b90 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -135,6 +135,7 @@

 use crate::alloc::{AllocError, Flags};
 use crate::{prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
+use core::ffi::CStr;
 use core::marker::PhantomData;

 /// Creates a [`Work`] initialiser with the given name and a newly-created lock
class.
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 7b71d6d99d5c..5246fed82e63 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -232,7 +232,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
             type LocalModule = {type_};

             impl kernel::ModuleMetadata for {type_} {{
-                const NAME: &'static kernel::str::CStr =
c\"{name}\";
+                const NAME: &'static core::ffi::CStr =
c\"{name}\";
             }}

             // Double nested modules, since then nobody can access the public
items inside.

--
2.49.0