kernel/
cpu.rs

1// SPDX-License-Identifier: GPL-2.0
2
3//! Generic CPU definitions.
4//!
5//! C header: [`include/linux/cpu.h`](srctree/include/linux/cpu.h)
6
7use crate::{bindings, device::Device, error::Result, prelude::ENODEV};
8
9/// Creates a new instance of CPU's device.
10///
11/// # Safety
12///
13/// Reference counting is not implemented for the CPU device in the C code. When a CPU is
14/// hot-unplugged, the corresponding CPU device is unregistered, but its associated memory
15/// is not freed.
16///
17/// Callers must ensure that the CPU device is not used after it has been unregistered.
18/// This can be achieved, for example, by registering a CPU hotplug notifier and removing
19/// any references to the CPU device within the notifier's callback.
20pub unsafe fn from_cpu(cpu: u32) -> Result<&'static Device> {
21    // SAFETY: It is safe to call `get_cpu_device()` for any CPU.
22    let ptr = unsafe { bindings::get_cpu_device(cpu) };
23    if ptr.is_null() {
24        return Err(ENODEV);
25    }
26
27    // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to
28    // a `struct device` and is never freed by the C code.
29    Ok(unsafe { Device::as_ref(ptr) })
30}
kernel/cpu.rs

kernel/
cpu.rs
