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rust: device: change the from_raw() function

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The function Device::from_raw() increments a refcount by a call to
bindings::get_device(ptr). This can be confused because usually
from_raw() functions don't increment a refcount.
Hence, rename Device::from_raw() to avoid confuion with other "from_raw"
semantics.

The new name of function should be "get_device" to be consistent with
the function get_device() already exist in .c files.

This function body also changed, because the `into()` will convert the
`&'a Device` into `ARef<Device>` and also call `inc_ref` from the
`AlwaysRefCounted` trait implemented for Device.

Signed-off-by: Guilherme Giacomo Simoes <trintaeoitogc@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Closes: https://github.com/Rust-for-Linux/linux/issues/1088
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241001205603.106278-1-trintaeoitogc@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Guilherme Giacomo Simoes 2024-10-01 17:56:03 -03:00 committed by Greg Kroah-Hartman
parent 9852d85ec9
commit cc4332afb5
2 changed files with 4 additions and 13 deletions
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15
rust/kernel/device.rs
View File

@ -51,18 +51,9 @@ impl Device {
///
/// It must also be ensured that `bindings::device::release` can be called from any thread.
/// While not officially documented, this should be the case for any `struct device`.
pub unsafe fn from_raw(ptr: *mut bindings::device) -> ARef<Self> {
// SAFETY: By the safety requirements, ptr is valid.
// Initially increase the reference count by one to compensate for the final decrement once
// this newly created `ARef<Device>` instance is dropped.
unsafe { bindings::get_device(ptr) };
// CAST: `Self` is a `repr(transparent)` wrapper around `bindings::device`.
let ptr = ptr.cast::<Self>();
// SAFETY: `ptr` is valid by the safety requirements of this function. By the above call to
// `bindings::get_device` we also own a reference to the underlying `struct device`.
unsafe { ARef::from_raw(ptr::NonNull::new_unchecked(ptr)) }
pub unsafe fn get_device(ptr: *mut bindings::device) -> ARef<Self> {
// SAFETY: By the safety requirements ptr is valid
unsafe { Self::as_ref(ptr) }.into()
}
/// Obtain the raw `struct device *`.

2
rust/kernel/firmware.rs
View File

@ -44,7 +44,7 @@ fn request_nowarn() -> Self {
///
/// # fn no_run() -> Result<(), Error> {
/// # // SAFETY: *NOT* safe, just for the example to get an `ARef<Device>` instance
/// # let dev = unsafe { Device::from_raw(core::ptr::null_mut()) };
/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };
///
/// let fw = Firmware::request(c_str!("path/to/firmware.bin"), &dev)?;
/// let blob = fw.data();