rust/kernel/firmware.rs | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
The `FwFunc` struct contains an function with a char pointer argument,
for which a `*const u8` pointer was used. This is not really the
"proper" type for this, so use a `*const kernel::ffi::c_char` pointer
instead.
This has no real functionality changes, since now `kernel::ffi::c_char`
(which bindgen uses for `char`) is now a type alias to `u8` anyways,
but before commit 1bae8729e50a ("rust: map `long` to `isize` and `char`
to `u8`") the concrete type of `kernel::ffi::c_char` depended on the
architecture (However all supported architectures at the time mapped to
`i8`).
This caused problems on the v6.13 tag when building for 32 bit arm (with
my patches), since back then `*const i8` was used in the function
argument and the function that bindgen generated used
`*const core::ffi::c_char` which Rust mapped to `*const u8` on 32 bit
arm. The stable v6.13.y branch does not have this issue since commit
1bae8729e50a ("rust: map `long` to `isize` and `char` to `u8`") was
backported.
This caused the following build error:
```
error[E0308]: mismatched types
--> rust/kernel/firmware.rs:20:4
|
20 | Self(bindings::request_firmware)
| ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected fn pointer, found fn item
| |
| arguments to this function are incorrect
|
= note: expected fn pointer `unsafe extern "C" fn(_, *const i8, _) -> _`
found fn item `unsafe extern "C" fn(_, *const u8, _) -> _ {request_firmware}`
note: tuple struct defined here
--> rust/kernel/firmware.rs:14:8
|
14 | struct FwFunc(
| ^^^^^^
error[E0308]: mismatched types
--> rust/kernel/firmware.rs:24:14
|
24 | Self(bindings::firmware_request_nowarn)
| ---- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected fn pointer, found fn item
| |
| arguments to this function are incorrect
|
= note: expected fn pointer `unsafe extern "C" fn(_, *const i8, _) -> _`
found fn item `unsafe extern "C" fn(_, *const u8, _) -> _ {firmware_request_nowarn}`
note: tuple struct defined here
--> rust/kernel/firmware.rs:14:8
|
14 | struct FwFunc(
| ^^^^^^
error[E0308]: mismatched types
--> rust/kernel/firmware.rs:64:45
|
64 | let ret = unsafe { func.0(pfw as _, name.as_char_ptr(), dev.as_raw()) };
| ------ ^^^^^^^^^^^^^^^^^^ expected `*const i8`, found `*const u8`
| |
| arguments to this function are incorrect
|
= note: expected raw pointer `*const i8`
found raw pointer `*const u8`
error: aborting due to 3 previous errors
```
Fixes: de6582833db0 ("rust: add firmware abstractions")
Cc: stable@vger.kernel.org
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Christian Schrefl <chrisi.schrefl@gmail.com>
---
Changes in v3:
- Clarify build issues with v6.13 in commit message.
- Link to v2: https://lore.kernel.org/r/20250412-rust_arm_fix_fw_abstaction-v2-1-8e6fdf093d71@gmail.com
Changes in v2:
- Use `kernel::ffi::c_char` instead of `core::ffi::c_char`. (Danilo & Benno)
- Reword the commit message.
- Link to v1: https://lore.kernel.org/r/20250411-rust_arm_fix_fw_abstaction-v1-1-0a9e598451c6@gmail.com
---
rust/kernel/firmware.rs | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
index f04b058b09b2d2397e26344d0e055b3aa5061432..2494c96e105f3a28af74548d63a44464ba50eae3 100644
--- a/rust/kernel/firmware.rs
+++ b/rust/kernel/firmware.rs
@@ -4,7 +4,7 @@
//!
//! C header: [`include/linux/firmware.h`](srctree/include/linux/firmware.h)
-use crate::{bindings, device::Device, error::Error, error::Result, str::CStr};
+use crate::{bindings, device::Device, error::Error, error::Result, ffi, str::CStr};
use core::ptr::NonNull;
/// # Invariants
@@ -12,7 +12,11 @@
/// One of the following: `bindings::request_firmware`, `bindings::firmware_request_nowarn`,
/// `bindings::firmware_request_platform`, `bindings::request_firmware_direct`.
struct FwFunc(
- unsafe extern "C" fn(*mut *const bindings::firmware, *const u8, *mut bindings::device) -> i32,
+ unsafe extern "C" fn(
+ *mut *const bindings::firmware,
+ *const ffi::c_char,
+ *mut bindings::device,
+ ) -> i32,
);
impl FwFunc {
---
base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
change-id: 20250408-rust_arm_fix_fw_abstaction-4c3a89d75e29
Best regards,
--
Christian Schrefl <chrisi.schrefl@gmail.com>On Sun, Apr 13, 2025 at 09:26:56PM +0200, Christian Schrefl wrote: > The `FwFunc` struct contains an function with a char pointer argument, > for which a `*const u8` pointer was used. This is not really the > "proper" type for this, so use a `*const kernel::ffi::c_char` pointer > instead. With the following changes, applied to driver-core-linus, thanks! * add firmware prefix to commit subject - Danilo
On Sun, Apr 13, 2025 at 9:27 PM Christian Schrefl <chrisi.schrefl@gmail.com> wrote: > > The `FwFunc` struct contains an function with a char pointer argument, > for which a `*const u8` pointer was used. This is not really the > "proper" type for this, so use a `*const kernel::ffi::c_char` pointer > instead. If I don't take it: Acked-by: Miguel Ojeda <ojeda@kernel.org> Thanks! Cheers, Miguel
On Sun, Apr 13, 2025 at 10:21:01PM +0200, Miguel Ojeda wrote: > On Sun, Apr 13, 2025 at 9:27 PM Christian Schrefl > <chrisi.schrefl@gmail.com> wrote: > > > > The `FwFunc` struct contains an function with a char pointer argument, > > for which a `*const u8` pointer was used. This is not really the > > "proper" type for this, so use a `*const kernel::ffi::c_char` pointer > > instead. > > If I don't take it: > > Acked-by: Miguel Ojeda <ojeda@kernel.org> Thanks, I'll take it now. greg k-h
On Tue, Apr 15, 2025 at 04:57:45PM +0200, Greg Kroah-Hartman wrote: > On Sun, Apr 13, 2025 at 10:21:01PM +0200, Miguel Ojeda wrote: > > On Sun, Apr 13, 2025 at 9:27 PM Christian Schrefl > > <chrisi.schrefl@gmail.com> wrote: > > > > > > The `FwFunc` struct contains an function with a char pointer argument, > > > for which a `*const u8` pointer was used. This is not really the > > > "proper" type for this, so use a `*const kernel::ffi::c_char` pointer > > > instead. > > > > If I don't take it: > > > > Acked-by: Miguel Ojeda <ojeda@kernel.org> > > Thanks, I'll take it now. Oops, it's already in the driver-core tree :)
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