Am 04.10.24 um 17:52 schrieb Gary Guo:
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.
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Gary Guo <gary@xxxxxxxxxxx>
---
...
diff --git a/rust/kernel/block/mq/request.rs b/rust/kernel/block/mq/request.rs
index a0e22827f3f4..7b63c02bdce7 100644
--- a/rust/kernel/block/mq/request.rs
+++ b/rust/kernel/block/mq/request.rs
....
@@ -37,6 +38,9 @@
/// We need to track C and D to ensure that it is safe to end the request and hand
/// back ownership to the block layer.
///
+/// Note that driver can still obtain new `ARef` even there is no `ARef`s in existence by using
Do you like to check this sentence? Maybe:
Note that "a" driver can still obtain "a" new `ARef` even "if" there
"are" no `ARef`s in existence by using ....
?
Best regards
Dirk
