From 47e6715bb7ea388a9a3a13d31918827ba3aa3f4a Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Sun, 13 Jul 2025 20:26:54 +0200 Subject: [PATCH] rust: device: implement Device::as_bound() Provide an unsafe functions for abstractions to convert a regular &Device to a &Device. This is useful for registrations that provide certain guarantees for the scope of their callbacks, such as IRQs or certain class device registrations (e.g. PWM, miscdevice). Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250713182737.64448-2-dakr@kernel.org [ Remove unnecessary cast(). - Danilo ] 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 d527ceef829e..b6b81546a0da 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -60,6 +60,25 @@ impl Device { // SAFETY: By the safety requirements ptr is valid unsafe { Self::as_ref(ptr) }.into() } + + /// Convert a [`&Device`](Device) into a [`&Device`](Device). + /// + /// # Safety + /// + /// The caller is responsible to ensure that the returned [`&Device`](Device) + /// only lives as long as it can be guaranteed that the [`Device`] is actually bound. + pub unsafe fn as_bound(&self) -> &Device { + let ptr = core::ptr::from_ref(self); + + // CAST: By the safety requirements the caller is responsible to guarantee that the + // returned reference only lives as long as the device is actually bound. + let ptr = ptr.cast(); + + // SAFETY: + // - `ptr` comes from `from_ref(self)` above, hence it's guaranteed to be valid. + // - Any valid `Device` pointer is also a valid pointer for `Device`. + unsafe { &*ptr } + } } impl Device { -- 2.47.2