* Re: [PATCH] rust: types: make `Opaque` be `!Unpin`
2023-06-30 15:03 [PATCH] rust: types: make `Opaque` be `!Unpin` Benno Lossin
@ 2023-06-30 15:32 ` Alice Ryhl
2023-06-30 17:52 ` Gary Guo
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Alice Ryhl @ 2023-06-30 15:32 UTC (permalink / raw)
To: Benno Lossin, Miguel Ojeda, Wedson Almeida Filho, Alex Gaynor
Cc: Boqun Feng, Gary Guo, Björn Roy Baron, Alice Ryhl,
Andreas Hindborg, rust-for-linux, linux-kernel, patches
On 6/30/23 17:03, Benno Lossin wrote:
> Adds a `PhantomPinned` field to `Opaque<T>`. This removes the last Rust
> guarantee: the assumption that the type `T` can be freely moved. This is
> not the case for many types from the C side (e.g. if they contain a
> `struct list_head`). This change removes the need to add a
> `PhantomPinned` field manually to Rust structs that contain C structs
> which must not be moved.
>
> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] rust: types: make `Opaque` be `!Unpin`
2023-06-30 15:03 [PATCH] rust: types: make `Opaque` be `!Unpin` Benno Lossin
2023-06-30 15:32 ` Alice Ryhl
@ 2023-06-30 17:52 ` Gary Guo
2023-07-03 9:30 ` Andreas Hindborg (Samsung)
2023-08-09 23:21 ` Miguel Ojeda
3 siblings, 0 replies; 5+ messages in thread
From: Gary Guo @ 2023-06-30 17:52 UTC (permalink / raw)
To: Benno Lossin
Cc: Miguel Ojeda, Wedson Almeida Filho, Alex Gaynor, Boqun Feng,
Björn Roy Baron, Alice Ryhl, Andreas Hindborg,
rust-for-linux, linux-kernel, patches
On Fri, 30 Jun 2023 15:03:23 +0000
Benno Lossin <benno.lossin@proton.me> wrote:
> Adds a `PhantomPinned` field to `Opaque<T>`. This removes the last Rust
> guarantee: the assumption that the type `T` can be freely moved. This is
> not the case for many types from the C side (e.g. if they contain a
> `struct list_head`). This change removes the need to add a
> `PhantomPinned` field manually to Rust structs that contain C structs
> which must not be moved.
>
> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
> ---
> This patch depends on the patch that swaps `UnsafeCell` with
> `MaybeUninit` inside `Opaque` [1].
>
> [1]: https://lore.kernel.org/rust-for-linux/20230614115328.2825961-1-aliceryhl@google.com/
> ---
> rust/kernel/types.rs | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index fb41635f1e1f..e664a2beef30 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -6,7 +6,7 @@
> use alloc::boxed::Box;
> use core::{
> cell::UnsafeCell,
> - marker::PhantomData,
> + marker::{PhantomData, PhantomPinned},
> mem::MaybeUninit,
> ops::{Deref, DerefMut},
> ptr::NonNull,
> @@ -224,17 +224,26 @@ fn drop(&mut self) {
> ///
> /// This is meant to be used with FFI objects that are never interpreted by Rust code.
> #[repr(transparent)]
> -pub struct Opaque<T>(UnsafeCell<MaybeUninit<T>>);
> +pub struct Opaque<T> {
> + value: UnsafeCell<MaybeUninit<T>>,
> + _pin: PhantomPinned,
> +}
>
> impl<T> Opaque<T> {
> /// Creates a new opaque value.
> pub const fn new(value: T) -> Self {
> - Self(UnsafeCell::new(MaybeUninit::new(value)))
> + Self {
> + value: UnsafeCell::new(MaybeUninit::new(value)),
> + _pin: PhantomPinned,
> + }
> }
>
> /// Creates an uninitialised value.
> pub const fn uninit() -> Self {
> - Self(UnsafeCell::new(MaybeUninit::uninit()))
> + Self {
> + value: UnsafeCell::new(MaybeUninit::uninit()),
> + _pin: PhantomPinned,
> + }
> }
>
> /// Creates a pin-initializer from the given initializer closure.
> @@ -258,7 +267,7 @@ pub fn ffi_init(init_func: impl FnOnce(*mut T)) -> impl PinInit<Self> {
>
> /// Returns a raw pointer to the opaque data.
> pub fn get(&self) -> *mut T {
> - UnsafeCell::get(&self.0).cast::<T>()
> + UnsafeCell::get(&self.value).cast::<T>()
> }
>
> /// Gets the value behind `this`.
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] rust: types: make `Opaque` be `!Unpin`
2023-06-30 15:03 [PATCH] rust: types: make `Opaque` be `!Unpin` Benno Lossin
2023-06-30 15:32 ` Alice Ryhl
2023-06-30 17:52 ` Gary Guo
@ 2023-07-03 9:30 ` Andreas Hindborg (Samsung)
2023-08-09 23:21 ` Miguel Ojeda
3 siblings, 0 replies; 5+ messages in thread
From: Andreas Hindborg (Samsung) @ 2023-07-03 9:30 UTC (permalink / raw)
To: Benno Lossin
Cc: Miguel Ojeda, Wedson Almeida Filho, Alex Gaynor, Boqun Feng,
Gary Guo, Björn Roy Baron, Alice Ryhl, rust-for-linux,
linux-kernel, patches
Benno Lossin <benno.lossin@proton.me> writes:
> Adds a `PhantomPinned` field to `Opaque<T>`. This removes the last Rust
> guarantee: the assumption that the type `T` can be freely moved. This is
> not the case for many types from the C side (e.g. if they contain a
> `struct list_head`). This change removes the need to add a
> `PhantomPinned` field manually to Rust structs that contain C structs
> which must not be moved.
>
> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
> ---
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
> This patch depends on the patch that swaps `UnsafeCell` with
> `MaybeUninit` inside `Opaque` [1].
>
> [1]: https://lore.kernel.org/rust-for-linux/20230614115328.2825961-1-aliceryhl@google.com/
> ---
> rust/kernel/types.rs | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index fb41635f1e1f..e664a2beef30 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -6,7 +6,7 @@
> use alloc::boxed::Box;
> use core::{
> cell::UnsafeCell,
> - marker::PhantomData,
> + marker::{PhantomData, PhantomPinned},
> mem::MaybeUninit,
> ops::{Deref, DerefMut},
> ptr::NonNull,
> @@ -224,17 +224,26 @@ fn drop(&mut self) {
> ///
> /// This is meant to be used with FFI objects that are never interpreted by Rust code.
> #[repr(transparent)]
> -pub struct Opaque<T>(UnsafeCell<MaybeUninit<T>>);
> +pub struct Opaque<T> {
> + value: UnsafeCell<MaybeUninit<T>>,
> + _pin: PhantomPinned,
> +}
>
> impl<T> Opaque<T> {
> /// Creates a new opaque value.
> pub const fn new(value: T) -> Self {
> - Self(UnsafeCell::new(MaybeUninit::new(value)))
> + Self {
> + value: UnsafeCell::new(MaybeUninit::new(value)),
> + _pin: PhantomPinned,
> + }
> }
>
> /// Creates an uninitialised value.
> pub const fn uninit() -> Self {
> - Self(UnsafeCell::new(MaybeUninit::uninit()))
> + Self {
> + value: UnsafeCell::new(MaybeUninit::uninit()),
> + _pin: PhantomPinned,
> + }
> }
>
> /// Creates a pin-initializer from the given initializer closure.
> @@ -258,7 +267,7 @@ pub fn ffi_init(init_func: impl FnOnce(*mut T)) -> impl PinInit<Self> {
>
> /// Returns a raw pointer to the opaque data.
> pub fn get(&self) -> *mut T {
> - UnsafeCell::get(&self.0).cast::<T>()
> + UnsafeCell::get(&self.value).cast::<T>()
> }
>
> /// Gets the value behind `this`.
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] rust: types: make `Opaque` be `!Unpin`
2023-06-30 15:03 [PATCH] rust: types: make `Opaque` be `!Unpin` Benno Lossin
` (2 preceding siblings ...)
2023-07-03 9:30 ` Andreas Hindborg (Samsung)
@ 2023-08-09 23:21 ` Miguel Ojeda
3 siblings, 0 replies; 5+ messages in thread
From: Miguel Ojeda @ 2023-08-09 23:21 UTC (permalink / raw)
To: Benno Lossin
Cc: Miguel Ojeda, Wedson Almeida Filho, Alex Gaynor, Boqun Feng,
Gary Guo, Björn Roy Baron, Alice Ryhl, Andreas Hindborg,
rust-for-linux, linux-kernel, patches
On Fri, Jun 30, 2023 at 5:03 PM Benno Lossin <benno.lossin@proton.me> wrote:
>
> Adds a `PhantomPinned` field to `Opaque<T>`. This removes the last Rust
> guarantee: the assumption that the type `T` can be freely moved. This is
> not the case for many types from the C side (e.g. if they contain a
> `struct list_head`). This change removes the need to add a
> `PhantomPinned` field manually to Rust structs that contain C structs
> which must not be moved.
>
> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Applied to `rust-next` -- thanks everyone!
Cheers,
Miguel
^ permalink raw reply [flat|nested] 5+ messages in thread