From 0fcccf3ff04a54d597bffcb7a42668c52a7dcec0 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 17 Jan 2025 12:00:01 +0100 Subject: rust: qom: add reference counting functionality Add a smart pointer that allows to add and remove references from QOM objects. It's important to note that while all QOM objects have a reference count, in practice not all of them have their lifetime guarded by it. Embedded objects, specifically, are confined to the lifetime of the owner. When writing Rust bindings this is important, because embedded objects are *never* used through the "Owned<>" smart pointer that is introduced here. Reviewed-by: Zhao Liu Signed-off-by: Paolo Bonzini --- rust/qemu-api/src/vmstate.rs | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'rust/qemu-api/src/vmstate.rs') diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/vmstate.rs index 6ac432cf52..11d21b8791 100644 --- a/rust/qemu-api/src/vmstate.rs +++ b/rust/qemu-api/src/vmstate.rs @@ -29,6 +29,8 @@ use core::{marker::PhantomData, mem, ptr::NonNull}; pub use crate::bindings::{VMStateDescription, VMStateField}; use crate::{ bindings::{self, VMStateFlags}, + prelude::*, + qom::Owned, zeroable::Zeroable, }; @@ -191,7 +193,8 @@ pub const fn vmstate_varray_flag(_: PhantomData) -> VMStateFlags /// * a transparent wrapper for any of the above (`Cell`, `UnsafeCell`, /// [`BqlCell`](crate::cell::BqlCell), [`BqlRefCell`](crate::cell::BqlRefCell) /// * a raw pointer to any of the above -/// * a `NonNull` pointer or a `Box` for any of the above +/// * a `NonNull` pointer, a `Box` or an [`Owned`](crate::qom::Owned) for any of +/// the above /// * an array of any of the above /// /// In order to support other types, the trait `VMState` must be implemented @@ -398,6 +401,7 @@ impl_vmstate_pointer!(NonNull where T: VMState); // Unlike C pointers, Box is always non-null therefore there is no need // to specify VMS_ALLOC. impl_vmstate_pointer!(Box where T: VMState); +impl_vmstate_pointer!(Owned where T: VMState + ObjectType); // Arrays using the underlying type's VMState plus // VMS_ARRAY/VMS_ARRAY_OF_POINTER -- cgit 1.4.1