linux-stable.git/rust/kernel/types.rs, branch linux-6.5.y

rust: types: make `Opaque` be `!Unpin`

2023-11-08T13:09:04+00:00

[ Upstream commit 0b4e3b6f6b79b1add04008a6ceaaf661107e8902 ]

Adds a `PhantomPinned` field to `Opaque`. 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 
Reviewed-by: Gary Guo 
Reviewed-by: Alice Ryhl 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20230630150216.109789-1-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda 
Signed-off-by: Sasha Levin

rust: make `UnsafeCell` the outer type in `Opaque`

2023-11-08T13:09:03+00:00

[ Upstream commit 35cad617df2eeef8440a38e82bb2d81ae32ca50d ]

When combining `UnsafeCell` with `MaybeUninit`, it is idiomatic to use
`UnsafeCell` as the outer type. Intuitively, this is because a
`MaybeUninit` might not contain a `T`, but we always want the effect
of the `UnsafeCell`, even if the inner value is uninitialized.

Now, strictly speaking, this doesn't really make a difference. The
compiler will always apply the `UnsafeCell` effect even if the inner
value is uninitialized. But I think we should follow the convention
here.

Signed-off-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Reviewed-by: Martin Rodriguez Reboredo 
Link: https://lore.kernel.org/r/20230614115328.2825961-1-aliceryhl@google.com
Signed-off-by: Miguel Ojeda 
Stable-dep-of: 0b4e3b6f6b79 ("rust: types: make `Opaque` be `!Unpin`")
Signed-off-by: Sasha Levin

rust: delete `ForeignOwnable::borrow_mut`

2023-08-04T15:10:50+00:00

We discovered that the current design of `borrow_mut` is problematic.
This patch removes it until a better solution can be found.

Specifically, the current design gives you access to a `&mut T`, which
lets you change where the `ForeignOwnable` points (e.g., with
`core::mem::swap`). No upcoming user of this API intended to make that
possible, making all of them unsound.

Signed-off-by: Alice Ryhl 
Reviewed-by: Gary Guo 
Reviewed-by: Benno Lossin 
Reviewed-by: Martin Rodriguez Reboredo 
Fixes: 0fc4424d24a2 ("rust: types: introduce `ForeignOwnable`")
Link: https://lore.kernel.org/r/20230706094615.3080784-1-aliceryhl@google.com
Signed-off-by: Miguel Ojeda

rust: specify when `ARef` is thread safe

2023-05-31T16:53:10+00:00

An `ARef` behaves just like the `Arc` when it comes to thread safety, so
we can reuse the thread safety comments from `Arc` here.

This is necessary because without this change, the Rust compiler will
assume that things are not thread safe even though they are.

Signed-off-by: Alice Ryhl 
Reviewed-by: Andreas Hindborg 
Reviewed-by: Boqun Feng 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: Benno Lossin 
Link: https://lore.kernel.org/r/20230531145939.3714886-4-aliceryhl@google.com
Signed-off-by: Miguel Ojeda

rust: introduce `ARef`

2023-04-21T22:20:00+00:00

This is an owned reference to an object that is always ref-counted. This
is meant to be used in wrappers for C types that have their own ref
counting functions, for example, tasks, files, inodes, dentries, etc.

Reviewed-by: Martin Rodriguez Reboredo 
Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Gary Guo 
Link: https://lore.kernel.org/r/20230411054543.21278-8-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda

rust: types: add `Opaque::ffi_init`

2023-04-12T16:41:05+00:00

This function allows to easily initialize `Opaque` with the pin-init
API. `Opaque::ffi_init` takes a closure and returns a pin-initializer.
This pin-initiailizer calls the given closure with a pointer to the
inner `T`.

Co-developed-by: Gary Guo 
Signed-off-by: Gary Guo 
Signed-off-by: Benno Lossin 
Reviewed-by: Andreas Hindborg 
Reviewed-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20230408122429.1103522-14-y86-dev@protonmail.com
[ Fixed typo. ]
Signed-off-by: Miguel Ojeda

rust: types: add `Opaque::raw_get`

2023-04-12T16:41:05+00:00

This function mirrors `UnsafeCell::raw_get`. It avoids creating a
reference and allows solely using raw pointers.
The `pin-init` API will be using this, since uninitialized memory
requires raw pointers.

Signed-off-by: Benno Lossin 
Reviewed-by: Gary Guo 
Reviewed-by: Andreas Hindborg 
Reviewed-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20230408122429.1103522-6-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda

rust: types: implement `ForeignOwnable` for the unit type

2023-02-01T12:24:36+00:00

This allows us to use the unit type `()` when we have no object whose
ownership must be managed but one implementing the `ForeignOwnable`
trait is needed.

Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Vincenzo Palazzo 
Reviewed-by: Gary Guo 
Reviewed-by: Andreas Hindborg 
Signed-off-by: Miguel Ojeda

rust: types: implement `ForeignOwnable` for `Box`

2023-02-01T12:24:19+00:00

This allows us to hand ownership of Rust dynamically allocated
objects to the C side of the kernel.

Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Gary Guo 
Reviewed-by: Vincenzo Palazzo 
Reviewed-by: Alice Ferrazzi 
Reviewed-by: Andreas Hindborg 
Signed-off-by: Miguel Ojeda

rust: types: introduce `ForeignOwnable`

2023-02-01T12:24:07+00:00

It was originally called `PointerWrapper`. It is used to convert
a Rust object to a pointer representation (void *) that can be
stored on the C side, used, and eventually returned to Rust.

Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Vincenzo Palazzo 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: Gary Guo 
Reviewed-by: Andreas Hindborg 
Signed-off-by: Miguel Ojeda