| a307bf1d | 05-Sep-2025 |
Gary Guo <gary@garyguo.net> |
rust: block: convert `block::mq` to use `Refcount`
Currently there's a custom reference counting in `block::mq`, which uses
`AtomicU64` Rust atomics, and this type doesn't exist on some 32-bit
archi
rust: block: convert `block::mq` to use `Refcount`
Currently there's a custom reference counting in `block::mq`, which uses
`AtomicU64` Rust atomics, and this type doesn't exist on some 32-bit
architectures. We cannot just change it to use 32-bit atomics, because
doing so will make it vulnerable to refcount overflow. So switch it to
use the kernel refcount `kernel::sync::Refcount` instead.
There is an operation needed by `block::mq`, atomically decreasing
refcount from 2 to 0, which is not available through refcount.h, so
I exposed `Refcount::as_atomic` which allows accessing the refcount
directly.
[boqun: Adopt the LKMM atomic API]
Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Acked-by: Andreas Hindborg <a.hindborg@kernel.org>
Tested-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20250723233312.3304339-5-gary@kernel.org
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| 076acb64 | 05-Sep-2025 |
Gary Guo <gary@garyguo.net> |
rust: convert `Arc` to use `Refcount`
With `Refcount` type created, `Arc` can use `Refcount` instead of
calling into FFI directly.
Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Fe
rust: convert `Arc` to use `Refcount`
With `Refcount` type created, `Arc` can use `Refcount` instead of
calling into FFI directly.
Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/r/20250723233312.3304339-4-gary@kernel.org
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| 7487645f | 05-Sep-2025 |
Gary Guo <gary@garyguo.net> |
rust: make `Arc::into_unique_or_drop` associated function
Make `Arc::into_unique_or_drop` to become a mere associated function
instead of a method (i.e. removing the `self` receiver).
It's a genera
rust: make `Arc::into_unique_or_drop` associated function
Make `Arc::into_unique_or_drop` to become a mere associated function
instead of a method (i.e. removing the `self` receiver).
It's a general convention for Rust smart pointers to avoid having
methods defined on them, because if the pointee type has a method of the
same name, then it is shadowed. This is normally for avoiding semver
breakage, which isn't an issue for kernel codebase, but it's still
generally a good practice to follow this rule, so that `ptr.foo()` would
always be calling a method on the pointee type.
Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/r/20250723233312.3304339-3-gary@kernel.org
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| bb38f35b | 05-Sep-2025 |
Gary Guo <gary@garyguo.net> |
rust: implement `kernel::sync::Refcount`
This is a wrapping layer of `include/linux/refcount.h`. Currently the
kernel refcount has already been used in `Arc`, however it calls into
FFI directly.
[b
rust: implement `kernel::sync::Refcount`
This is a wrapping layer of `include/linux/refcount.h`. Currently the
kernel refcount has already been used in `Arc`, however it calls into
FFI directly.
[boqun: Add the missing <> for the link in comment]
Signed-off-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/r/20250723233312.3304339-2-gary@kernel.org
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| d9ea5a41 | 05-Sep-2025 |
Boqun Feng <boqun.feng@gmail.com> |
rust: sync: Add memory barriers
Memory barriers are building blocks for concurrent code, hence provide
a minimal set of them.
The compiler barrier, barrier(), is implemented in inline asm instead o
rust: sync: Add memory barriers
Memory barriers are building blocks for concurrent code, hence provide
a minimal set of them.
The compiler barrier, barrier(), is implemented in inline asm instead of
using core::sync::atomic::compiler_fence() because memory models are
different: kernel's atomics are implemented in inline asm therefore the
compiler barrier should be implemented in inline asm as well. Also it's
currently only public to the kernel crate until there's a reasonable
driver usage.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-10-boqun.feng@gmail.com/
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| 84c6d36b | 05-Sep-2025 |
Boqun Feng <boqun.feng@gmail.com> |
rust: sync: atomic: Add Atomic<{usize,isize}>
Add generic atomic support for `usize` and `isize`. Note that instead of
mapping directly to `atomic_long_t`, the represention type
(`AtomicType::Repr`)
rust: sync: atomic: Add Atomic<{usize,isize}>
Add generic atomic support for `usize` and `isize`. Note that instead of
mapping directly to `atomic_long_t`, the represention type
(`AtomicType::Repr`) is selected based on CONFIG_64BIT. This reduces
the necessity of creating `atomic_long_*` helpers, which could save
the binary size of kernel if inline helpers are not available. To do so,
an internal type `isize_atomic_repr` is defined, it's `i32` in 32bit
kernel and `i64` in 64bit kernel.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-9-boqun.feng@gmail.com/
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| d6df37ba | 05-Sep-2025 |
Boqun Feng <boqun.feng@gmail.com> |
rust: sync: atomic: Add Atomic<u{32,64}>
Add generic atomic support for basic unsigned types that have an
`AtomicImpl` with the same size and alignment.
Unit tests are added including Atomic<i32> a
rust: sync: atomic: Add Atomic<u{32,64}>
Add generic atomic support for basic unsigned types that have an
`AtomicImpl` with the same size and alignment.
Unit tests are added including Atomic<i32> and Atomic<i64>.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-8-boqun.feng@gmail.com/
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| d1320543 | 05-Sep-2025 |
Boqun Feng <boqun.feng@gmail.com> |
rust: sync: atomic: Add the framework of arithmetic operations
One important set of atomic operations is the arithmetic operations,
i.e. add(), sub(), fetch_add(), add_return(), etc. However it may
rust: sync: atomic: Add the framework of arithmetic operations
One important set of atomic operations is the arithmetic operations,
i.e. add(), sub(), fetch_add(), add_return(), etc. However it may not
make senses for all the types that `AtomicType` to have arithmetic
operations, for example a `Foo(u32)` may not have a reasonable add() or
sub(), plus subword types (`u8` and `u16`) currently don't have
atomic arithmetic operations even on C side and might not have them in
the future in Rust (because they are usually suboptimal on a few
architecures). Therefore the plan is to add a few subtraits of
`AtomicType` describing which types have and can do atomic arithemtic
operations.
One trait `AtomicAdd` is added, and only add() and fetch_add() are
added. The rest will be added in the future.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-7-boqun.feng@gmail.com/
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| b606a532 | 05-Sep-2025 |
Boqun Feng <boqun.feng@gmail.com> |
rust: sync: atomic: Add atomic {cmp,}xchg operations
xchg() and cmpxchg() are basic operations on atomic. Provide these based
on C APIs.
Note that cmpxchg() use the similar function signature as
co
rust: sync: atomic: Add atomic {cmp,}xchg operations
xchg() and cmpxchg() are basic operations on atomic. Provide these based
on C APIs.
Note that cmpxchg() use the similar function signature as
compare_exchange() in Rust std: returning a `Result`, `Ok(old)` means
the operation succeeds and `Err(old)` means the operation fails.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-6-boqun.feng@gmail.com/
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| 29c32c40 | 05-Sep-2025 |
Boqun Feng <boqun.feng@gmail.com> |
rust: sync: atomic: Add generic atomics
To provide using LKMM atomics for Rust code, a generic `Atomic<T>` is
added, currently `T` needs to be Send + Copy because these are the
straightforward usage
rust: sync: atomic: Add generic atomics
To provide using LKMM atomics for Rust code, a generic `Atomic<T>` is
added, currently `T` needs to be Send + Copy because these are the
straightforward usages and all basic types support this.
Implement `AtomicType` for `i32` and `i64`, and so far only basic
operations load() and store() are introduced.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-5-boqun.feng@gmail.com/
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| b638c9bc | 05-Sep-2025 |
Boqun Feng <boqun.feng@gmail.com> |
rust: sync: atomic: Add ordering annotation types
Preparation for atomic primitives. Instead of a suffix like _acquire, a
method parameter along with the corresponding generic parameter will be
used
rust: sync: atomic: Add ordering annotation types
Preparation for atomic primitives. Instead of a suffix like _acquire, a
method parameter along with the corresponding generic parameter will be
used to specify the ordering of an atomic operations. For example,
atomic load() can be defined as:
impl<T: ...> Atomic<T> {
pub fn load<O: AcquireOrRelaxed>(&self, _o: O) -> T { ... }
}
and acquire users would do:
let r = x.load(Acquire);
relaxed users:
let r = x.load(Relaxed);
doing the following:
let r = x.load(Release);
will cause a compiler error.
Compared to suffixes, it's easier to tell what ordering variants an
operation has, and it also make it easier to unify the implementation of
all ordering variants in one method via generic. The `TYPE` associate
const is for generic function to pick up the particular implementation
specified by an ordering annotation.
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>
Link: https://lore.kernel.org/all/20250719030827.61357-4-boqun.feng@gmail.com/
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| 12717ebe | 12-Jun-2025 |
Andreas Hindborg <a.hindborg@kernel.org> |
rust: types: add FOREIGN_ALIGN to ForeignOwnable
The current implementation of `ForeignOwnable` is leaking the type of the
opaque pointer to consumers of the API. This allows consumers of the opaque
rust: types: add FOREIGN_ALIGN to ForeignOwnable
The current implementation of `ForeignOwnable` is leaking the type of the
opaque pointer to consumers of the API. This allows consumers of the opaque
pointer to rely on the information that can be extracted from the pointer
type.
To prevent this, change the API to the version suggested by Maira
Canal (link below): Remove `ForeignOwnable::PointedTo` in favor of a
constant, which specifies the alignment of the pointers returned by
`into_foreign`.
With this change, `ArcInner` no longer needs `pub` visibility, so change it
to private.
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Suggested-by: Maíra Canal <mcanal@igalia.com>
Link: https://lore.kernel.org/r/20240309235927.168915-3-mcanal@igalia.com
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250612-pointed-to-v3-1-b009006d86a1@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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