From a4c9f71e3440dc6e944fa05bb7fcb3949fe5bcd4 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Mon, 14 Apr 2025 15:18:05 +0200 Subject: [PATCH] rust: device: implement Device::parent() Device::parent() returns a reference to the device' parent device, if any. Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250414131934.28418-3-dakr@kernel.org Signed-off-by: Danilo Krummrich --- rust/kernel/device.rs | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 0353c5552769..0d237cebd65e 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -67,6 +67,25 @@ impl Device { self.0.get() } + /// Returns a reference to the parent device, if any. + #[expect(unused)] + pub(crate) fn parent(&self) -> Option<&Self> { + // SAFETY: + // - By the type invariant `self.as_raw()` is always valid. + // - The parent device is only ever set at device creation. + let parent = unsafe { (*self.as_raw()).parent }; + + if parent.is_null() { + None + } else { + // SAFETY: + // - Since `parent` is not NULL, it must be a valid pointer to a `struct device`. + // - `parent` is valid for the lifetime of `self`, since a `struct device` holds a + // reference count of its parent. + Some(unsafe { Self::as_ref(parent) }) + } + } + /// Convert a raw C `struct device` pointer to a `&'a Device`. /// /// # Safety -- 2.50.1