Messages in this thread | | | Date | Sat, 04 Feb 2023 19:48:08 +0100 | Subject | Re: [RFC 2/5] rust: sync: Arc: Introduces ArcInner::count() | From | "Vincenzo Palazzo" <> |
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On Thu Feb 2, 2023 at 12:22 AM CET, Boqun Feng wrote: > This allows reading the current count of a refcount in an `ArcInner`. > > Signed-off-by: Boqun Feng <boqun.feng@gmail.com> > --- Reviwed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
> rust/helpers.c | 6 ++++++ > rust/kernel/sync/arc.rs | 9 +++++++++ > 2 files changed, 15 insertions(+) > > diff --git a/rust/helpers.c b/rust/helpers.c > index 09a4d93f9d62..afc5f1a39fef 100644 > --- a/rust/helpers.c > +++ b/rust/helpers.c > @@ -46,6 +46,12 @@ bool rust_helper_refcount_dec_and_test(refcount_t *r) > } > EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test); > > +unsigned int rust_helper_refcount_read(refcount_t *r) > +{ > + return refcount_read(r); > +} > +EXPORT_SYMBOL_GPL(rust_helper_refcount_read); > + > /* > * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type > * as the Rust `usize` type, so we can use it in contexts where Rust > diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs > index fc680a4a795c..fbfceaa3096e 100644 > --- a/rust/kernel/sync/arc.rs > +++ b/rust/kernel/sync/arc.rs > @@ -127,6 +127,15 @@ struct ArcInner<T: ?Sized> { > data: T, > } > > +impl<T: ?Sized> ArcInner<T> { > + /// Returns the current reference count of [`ArcInner`]. > + fn count(&self) -> u32 { > + // SAFETY: `self.refcount.get()` is always a valid pointer, and `refcount_read()` is a > + // normal atomic read (i.e. no data race) only requiring on the address is valid. > + unsafe { bindings::refcount_read(self.refcount.get()) } > + } > +} > + > // This is to allow [`Arc`] (and variants) to be used as the type of `self`. > impl<T: ?Sized> core::ops::Receiver for Arc<T> {} > > -- > 2.39.1
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