linux-toradex.git/rust/kernel/sync, branch v6.4-rc1

rust: sync: introduce `CondVar`

2023-04-21T23:46:45+00:00

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 
Cc: Ingo Molnar 
Cc: Will Deacon 
Cc: Waiman Long 
Reviewed-by: Martin Rodriguez Reboredo 
Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20230411054543.21278-12-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda

rust: lock: add `Guard::do_unlocked`

2023-04-21T23:46:30+00:00

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 
Signed-off-by: Wedson Almeida Filho 
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

rust: sync: introduce `LockedBy`

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

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 
Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Benno Lossin 
Link: https://lore.kernel.org/r/20230411054543.21278-13-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda

rust: lock: introduce `SpinLock`

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

This is the `spinlock_t` lock backend and allows Rust code to use the
kernel spinlock idiomatically.

Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Will Deacon 
Cc: Waiman Long 
Reviewed-by: Martin Rodriguez Reboredo 
Signed-off-by: Wedson Almeida Filho 
Link: https://lore.kernel.org/r/20230419174426.132207-1-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda

rust: lock: introduce `Mutex`

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

This is the `struct mutex` lock backend and allows Rust code to use the
kernel mutex idiomatically.

Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Will Deacon 
Cc: Waiman Long 
Reviewed-by: Martin Rodriguez Reboredo 
Signed-off-by: Wedson Almeida Filho 
Link: https://lore.kernel.org/r/20230411054543.21278-3-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda

rust: sync: introduce `Lock` and `Guard`

2023-04-21T22:19:42+00:00

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 
Suggested-by: Gary Guo 
Signed-off-by: Wedson Almeida Filho 
Link: https://lore.kernel.org/r/20230411054543.21278-2-wedsonaf@gmail.com
[ Fixed typo. ]
Signed-off-by: Miguel Ojeda

rust: sync: add functions for initializing `UniqueArc>`

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

Add two functions `init_with` and `pin_init_with` to
`UniqueArc>` 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 
Reviewed-by: Gary Guo 
Reviewed-by: Alice Ryhl 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20230408122429.1103522-16-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda

rust: sync: reduce stack usage of `UniqueArc::try_new_uninit`

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

`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 
Reviewed-by: Alice Ryhl 
Reviewed-by: Gary Guo 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20230408122429.1103522-15-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda

rust: init/sync: add `InPlaceInit` trait to pin-initialize smart pointers

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

The `InPlaceInit` trait that provides two functions, for initializing
using `PinInit` and `Init`. It is implemented by `Arc`,
`UniqueArc` and `Box`.

Signed-off-by: Benno Lossin 
Reviewed-by: Alice Ryhl 
Reviewed-by: Gary Guo 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20230408122429.1103522-9-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda

rust: sync: change error type of constructor functions

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

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 
Reviewed-by: Andreas Hindborg 
Reviewed-by: Alice Ryhl 
Reviewed-by: Gary Guo 
Link: https://lore.kernel.org/r/20230408122429.1103522-4-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda