Commit b9ff1c2a authored by Shankari Anand's avatar Shankari Anand Committed by Greg Kroah-Hartman
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rust: miscdevice: clarify invariant for `MiscDeviceRegistration` 



Reword and expand the invariant documentation for `MiscDeviceRegistration`
to clarify what it means for the inner device to be "registered".
It expands to explain:
- `inner` points to a `miscdevice` registered via `misc_register`.
- This registration stays valid for the entire lifetime of the object.
- Deregistration is guaranteed on `Drop`, via `misc_deregister`.

Reported-by: default avatarBenno Lossin <lossin@kernel.org>
Closes: https://github.com/Rust-for-Linux/linux/issues/1168


Fixes: f893691e ("rust: miscdevice: add base miscdevice abstraction")
Signed-off-by: default avatarShankari Anand <shankari.ak0208@gmail.com>
Link: https://lore.kernel.org/r/20250626104520.563036-1-shankari.ak0208@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9b5cdd5f

rust/kernel/miscdevice.rs

+7 −1
Original line number Diff line number Diff line
@@ -45,7 +45,13 @@ pub const fn into_raw<T: MiscDevice>(self) -> bindings::miscdevice { 
///

/// # Invariants

///

/// `inner` is a registered misc device.

/// - `inner` contains a `struct miscdevice` that is registered using

///   `misc_register()`.

/// - This registration remains valid for the entire lifetime of the

///   [`MiscDeviceRegistration`] instance.

/// - Deregistration occurs exactly once in [`Drop`] via `misc_deregister()`.

/// - `inner` wraps a valid, pinned `miscdevice` created using

///   [`MiscDeviceOptions::into_raw`].

#[repr(transparent)]

#[pin_data(PinnedDrop)]

pub struct MiscDeviceRegistration<T> {