[PATCH 0/3] implement `kernel::sync::Refcount` and convert users

[Gary Guo <gary@garyguo.net>]

Currently there're two refcount usage in rust/, `Arc` and `block::mq`.
`Arc` uses `refcount_t` with FFI calls directly, and `block::mq` use
Rust atomics and custom refcounting.

This series consolidate them to have a single `Refcount` which wraps
`refcount_t` and have it used by both.

With the removal of Rust `AtomicU64` this would also make the code work
for 32-bit systems. See [1] as a previous attempt to fix this issue.

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>
Link: https://lore.kernel.org/rust-for-linux/20240905061214.3954271-1-davidgow@google.com/ [1]

Gary Guo (3):
  rust: implement `kernel::sync::Refcount`
  rust: convert `Arc` to use `Refcount`
  rust: block: convert `block::mq` to use `Refcount`

 rust/helpers/refcount.c            |  15 ++++
 rust/kernel/block/mq/operations.rs |   7 +-
 rust/kernel/block/mq/request.rs    |  70 ++++++-------------
 rust/kernel/sync.rs                |   2 +
 rust/kernel/sync/arc.rs            |  45 ++++++------
 rust/kernel/sync/refcount.rs       | 106 +++++++++++++++++++++++++++++
 6 files changed, 168 insertions(+), 77 deletions(-)
 create mode 100644 rust/kernel/sync/refcount.rs


base-commit: c94d8cdb9ade6357824d6c2338e03d1cc726d43a
-- 
2.44.1