Messages in this thread | | | From | "Andreas Hindborg (Samsung)" <> | Subject | Re: [PATCH v2 6/8] rust: workqueue: implement `WorkItemPointer` for pointer types | Date | Fri, 02 Jun 2023 16:42:44 +0200 |
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Alice Ryhl <aliceryhl@google.com> writes:
> This implements the `WorkItemPointer` trait for the pointer types that > you are likely to use the workqueue with. The `Arc` type is for > reference counted objects, and the `Pin<Box<T>>` type is for objects > where the caller has exclusive ownership of the object. > > Co-developed-by: Gary Guo <gary@garyguo.net> > Signed-off-by: Gary Guo <gary@garyguo.net> > Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg (Samsung) <nmi@metaspace.dk>
> --- > rust/kernel/workqueue.rs | 97 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 96 insertions(+), 1 deletion(-) > > diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs > index dbf0aab29a85..f06a2f036d8b 100644 > --- a/rust/kernel/workqueue.rs > +++ b/rust/kernel/workqueue.rs > @@ -28,8 +28,10 @@ > //! > //! C header: [`include/linux/workqueue.h`](../../../../include/linux/workqueue.h) > > -use crate::{bindings, prelude::*, types::Opaque}; > +use crate::{bindings, prelude::*, sync::Arc, types::Opaque}; > +use alloc::boxed::Box; > use core::marker::{PhantomData, PhantomPinned}; > +use core::pin::Pin; > > /// A kernel work queue. > /// > @@ -323,6 +325,99 @@ unsafe fn raw_get_work(ptr: *mut Self) -> *mut $crate::workqueue::Work<$work_typ > )*}; > } > > +unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T> > +where > + T: WorkItem<ID, Pointer = Self>, > + T: HasWork<T, ID>, > +{ > + unsafe extern "C" fn run(ptr: *mut bindings::work_struct) { > + // SAFETY: The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`. > + let ptr = ptr as *mut Work<T, ID>; > + // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`. > + let ptr = unsafe { T::work_container_of(ptr) }; > + // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership. > + let arc = unsafe { Arc::from_raw(ptr) }; > + > + T::run(arc) > + } > +} > + > +unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T> > +where > + T: WorkItem<ID, Pointer = Self>, > + T: HasWork<T, ID>, > +{ > + type EnqueueOutput = Result<(), Self>; > + > + unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput > + where > + F: FnOnce(*mut bindings::work_struct) -> bool, > + { > + // Casting between const and mut is not a problem as long as the pointer is a raw pointer. > + let ptr = Arc::into_raw(self) as *mut T; > + > + // SAFETY: Pointers into an `Arc` point at a valid value. > + let work_ptr = unsafe { T::raw_get_work(ptr) }; > + // SAFETY: `raw_get_work` returns a pointer to a valid value. > + let work_ptr = unsafe { Work::raw_get(work_ptr) }; > + > + if queue_work_on(work_ptr) { > + Ok(()) > + } else { > + // SAFETY: The work queue has not taken ownership of the pointer. > + Err(unsafe { Arc::from_raw(ptr) }) > + } > + } > +} > + > +unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<Box<T>> > +where > + T: WorkItem<ID, Pointer = Self>, > + T: HasWork<T, ID>, > +{ > + unsafe extern "C" fn run(ptr: *mut bindings::work_struct) { > + // SAFETY: The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`. > + let ptr = ptr as *mut Work<T, ID>; > + // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`. > + let ptr = unsafe { T::work_container_of(ptr) }; > + // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership. > + let boxed = unsafe { Box::from_raw(ptr) }; > + // SAFETY: The box was already pinned when it was enqueued. > + let pinned = unsafe { Pin::new_unchecked(boxed) }; > + > + T::run(pinned) > + } > +} > + > +unsafe impl<T, const ID: u64> RawWorkItem<ID> for Pin<Box<T>> > +where > + T: WorkItem<ID, Pointer = Self>, > + T: HasWork<T, ID>, > +{ > + type EnqueueOutput = (); > + > + unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput > + where > + F: FnOnce(*mut bindings::work_struct) -> bool, > + { > + // SAFETY: We're not going to move `self` or any of its fields, so its okay to temporarily > + // remove the `Pin` wrapper. > + let boxed = unsafe { Pin::into_inner_unchecked(self) }; > + let ptr = Box::into_raw(boxed); > + > + // SAFETY: Pointers into a `Box` point at a valid value. > + let work_ptr = unsafe { T::raw_get_work(ptr) }; > + // SAFETY: `raw_get_work` returns a pointer to a valid value. > + let work_ptr = unsafe { Work::raw_get(work_ptr) }; > + > + if !queue_work_on(work_ptr) { > + // SAFETY: This method requires exclusive ownership of the box, so it cannot be in a > + // workqueue. > + unsafe { ::core::hint::unreachable_unchecked() } > + } > + } > +} > + > /// Returns the system work queue (`system_wq`). > /// > /// It is the one used by `schedule[_delayed]_work[_on]()`. Multi-CPU multi-threaded. There are
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