This is the traditional condition variable or monitor synchronisation
primitive. It is implemented with C's `wait_queue_head_t`.
It allows users to release a lock and go to sleep while guaranteeing
that notifications won't be missed. This is achieved by enqueuing a wait
entry before releasing the lock.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20230411054543.21278-12-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
It releases the lock, executes some function provided by the caller,
then reacquires the lock. This is preparation for the implementation of
condvars, which will sleep after between unlocking and relocking.
We need an explicit `relock` method for primitives like `SpinLock` that
have an irqsave variant: we use the guard state to determine if the lock
was originally acquired with the regular `lock` function or
`lock_irqsave`.
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/rust-for-linux/20230412121431.41627-1-wedsonaf@gmail.com/
[ Removed the irqsave bits as discussed. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This allows us to have data protected by a lock despite not being
wrapped by it. Access is granted by providing evidence that the lock is
held by the caller.
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230411054543.21278-13-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This is the `spinlock_t` lock backend and allows Rust code to use the
kernel spinlock idiomatically.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230419174426.132207-1-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This is the `struct mutex` lock backend and allows Rust code to use the
kernel mutex idiomatically.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230411054543.21278-3-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
They are generic Rust implementations of a lock and a lock guard that
contain code that is common to all locks. Different backends will be
introduced in subsequent commits.
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230411054543.21278-2-wedsonaf@gmail.com
[ Fixed typo. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Add two functions `init_with` and `pin_init_with` to
`UniqueArc<MaybeUninit<T>>` to initialize the memory of already allocated
`UniqueArc`s. This is useful when you want to allocate memory check some
condition inside of a context where allocation is forbidden and then
conditionally initialize an object.
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230408122429.1103522-16-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
`UniqueArc::try_new_uninit` calls `Arc::try_new(MaybeUninit::uninit())`.
This results in the uninitialized memory being placed on the stack,
which may be arbitrarily large due to the generic `T` and thus could
cause a stack overflow for large types.
Change the implementation to use the pin-init API which enables in-place
initialization. In particular it avoids having to first construct and
then move the uninitialized memory from the stack into the final location.
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230408122429.1103522-15-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The `InPlaceInit` trait that provides two functions, for initializing
using `PinInit<T, E>` and `Init<T>`. It is implemented by `Arc<T>`,
`UniqueArc<T>` and `Box<T>`.
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230408122429.1103522-9-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Change the error type of the constructors of `Arc` and `UniqueArc` to be
`AllocError` instead of `Error`. This makes the API more clear as to
what can go wrong when calling `try_new` or its variants.
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20230408122429.1103522-4-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
We can already create `UniqueArc<MaybeUninit<T>>` instances with
`UniqueArc::try_new_uninit()` and write to them with `write()`. Add
the missing unsafe `assume_init()` function to promote it to
`UniqueArc<T>`, so users can do piece-wise initialization of the
contents instead of doing it all at once as long as they keep the
invariants (the same requirements as `MaybeUninit::assume_init()`).
This mirrors the std `Arc::assume_init()` function. In the kernel,
since we have `UniqueArc`, arguably this only belongs there since most
use cases will initialize it immediately after creating it, before
demoting it to `Arc` to share it.
[ Miguel: The "Rust pin-init API for pinned initialization of structs"
patch series [1] from Benno Lossin contains a very similar patch:
rust: sync: add `assume_init` to `UniqueArc`
Adds the `assume_init` function to `UniqueArc<MaybeUninit<T>>` that
unsafely assumes the value to be initialized and yields a value of type
`UniqueArc<T>`. This function is used when manually initializing the
pointee of an `UniqueArc`.
To make that patch a noop and thus drop it, I adjusted the `SAFETY`
comment here to be the same as in the current latest version of
that series (v7).
I have also brought the `Reviewed-by`s there into here, and reworded
the `Co-authored-by` into `Co-developed-by`. ]
Link: https://lore.kernel.org/r/20230408122429.1103522-5-y86-dev@protonmail.com [1]
Co-developed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Wedson Almeida Filho <walmeida@microsoft.com>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20230224-rust-arc-v2-2-5c97a865b276@asahilina.net
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This allows printing the inner data of `Arc` and its friends if the
inner data implements `Display` or `Debug`. It's useful for logging and
debugging purpose.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20230207185216.1314638-2-boqun.feng@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This allows us to hand ownership of Rust ref-counted objects to
the C side of the kernel.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Reviewed-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Trait objects (`dyn T`) require trait `T` to be "object safe". One of
the requirements for "object safety" is that the receiver have one of
the allowed types. This commit adds `Arc<T>` and `ArcBorrow<'_, T>` to
the list of allowed types.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Since `Arc<T>` does not allow mutating `T` directly (i.e., without inner
mutability), it is currently not possible to do some initialisation of
`T` post construction but before being shared.
`UniqueArc<T>` addresses this problem essentially being an `Arc<T>` that
has a refcount of 1 and is therefore writable. Once initialisation is
completed, it can be transitioned (without failure paths) into an
`Arc<T>`.
Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This allows associated functions whose `self` argument has
`ArcBorrow<T>` as their type. This, in turn, allows callers to use the
dot syntax to make calls.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This allows us to create references to a ref-counted allocation without
double-indirection and that still allow us to increment the refcount to
a new `Arc<T>`.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
The coercion is only allowed if `U` is a compatible dynamically-sized
type (DST). For example, if we have some type `X` that implements trait
`Y`, then this allows `Arc<X>` to be coerced into `Arc<dyn Y>`.
Suggested-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This allows associated functions whose `self` argument has `Arc<T>` or
variants as their type. This, in turn, allows callers to use the dot
syntax to make calls.
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This is a basic implementation of `Arc` backed by C's `refcount_t`. It
allows Rust code to idiomatically allocate memory that is ref-counted.
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Wedson Almeida Filho