diff options
Diffstat (limited to 'rust/kernel/block/mq/operations.rs')
| -rw-r--r-- | rust/kernel/block/mq/operations.rs | 72 |
1 files changed, 56 insertions, 16 deletions
diff --git a/rust/kernel/block/mq/operations.rs b/rust/kernel/block/mq/operations.rs index c2b98f507bcb..f91a1719886c 100644 --- a/rust/kernel/block/mq/operations.rs +++ b/rust/kernel/block/mq/operations.rs @@ -6,13 +6,15 @@ use crate::{ bindings, - block::mq::request::RequestDataWrapper, - block::mq::Request, + block::mq::{request::RequestDataWrapper, Request}, error::{from_result, Result}, prelude::*, - types::ARef, + sync::Refcount, + types::{ARef, ForeignOwnable}, }; -use core::{marker::PhantomData, sync::atomic::AtomicU64, sync::atomic::Ordering}; +use core::marker::PhantomData; + +type ForeignBorrowed<'a, T> = <T as ForeignOwnable>::Borrowed<'a>; /// Implement this trait to interface blk-mq as block devices. /// @@ -26,12 +28,23 @@ use core::{marker::PhantomData, sync::atomic::AtomicU64, sync::atomic::Ordering} /// [module level documentation]: kernel::block::mq #[macros::vtable] pub trait Operations: Sized { + /// Data associated with the `struct request_queue` that is allocated for + /// the `GenDisk` associated with this `Operations` implementation. + type QueueData: ForeignOwnable; + /// Called by the kernel to queue a request with the driver. If `is_last` is /// `false`, the driver is allowed to defer committing the request. - fn queue_rq(rq: ARef<Request<Self>>, is_last: bool) -> Result; + fn queue_rq( + queue_data: ForeignBorrowed<'_, Self::QueueData>, + rq: ARef<Request<Self>>, + is_last: bool, + ) -> Result; /// Called by the kernel to indicate that queued requests should be submitted. - fn commit_rqs(); + fn commit_rqs(queue_data: ForeignBorrowed<'_, Self::QueueData>); + + /// Called by the kernel when the request is completed. + fn complete(rq: ARef<Request<Self>>); /// Called by the kernel to poll the device for completed requests. Only /// used for poll queues. @@ -70,7 +83,7 @@ impl<T: Operations> OperationsVTable<T> { /// promise to not access the request until the driver calls /// `bindings::blk_mq_end_request` for the request. unsafe extern "C" fn queue_rq_callback( - _hctx: *mut bindings::blk_mq_hw_ctx, + hctx: *mut bindings::blk_mq_hw_ctx, bd: *const bindings::blk_mq_queue_data, ) -> bindings::blk_status_t { // SAFETY: `bd.rq` is valid as required by the safety requirement for @@ -78,7 +91,7 @@ impl<T: Operations> OperationsVTable<T> { let request = unsafe { &*(*bd).rq.cast::<Request<T>>() }; // One refcount for the ARef, one for being in flight - request.wrapper_ref().refcount().store(2, Ordering::Relaxed); + request.wrapper_ref().refcount().set(2); // SAFETY: // - We own a refcount that we took above. We pass that to `ARef`. @@ -88,10 +101,20 @@ impl<T: Operations> OperationsVTable<T> { // reference counted by `ARef` until then. let rq = unsafe { Request::aref_from_raw((*bd).rq) }; + // SAFETY: `hctx` is valid as required by this function. + let queue_data = unsafe { (*(*hctx).queue).queuedata }; + + // SAFETY: `queue.queuedata` was created by `GenDiskBuilder::build` with + // a call to `ForeignOwnable::into_foreign` to create `queuedata`. + // `ForeignOwnable::from_foreign` is only called when the tagset is + // dropped, which happens after we are dropped. + let queue_data = unsafe { T::QueueData::borrow(queue_data) }; + // SAFETY: We have exclusive access and we just set the refcount above. unsafe { Request::start_unchecked(&rq) }; let ret = T::queue_rq( + queue_data, rq, // SAFETY: `bd` is valid as required by the safety requirement for // this function. @@ -110,18 +133,35 @@ impl<T: Operations> OperationsVTable<T> { /// /// # Safety /// - /// This function may only be called by blk-mq C infrastructure. - unsafe extern "C" fn commit_rqs_callback(_hctx: *mut bindings::blk_mq_hw_ctx) { - T::commit_rqs() + /// This function may only be called by blk-mq C infrastructure. The caller + /// must ensure that `hctx` is valid. + unsafe extern "C" fn commit_rqs_callback(hctx: *mut bindings::blk_mq_hw_ctx) { + // SAFETY: `hctx` is valid as required by this function. + let queue_data = unsafe { (*(*hctx).queue).queuedata }; + + // SAFETY: `queue.queuedata` was created by `GenDisk::try_new()` with a + // call to `ForeignOwnable::into_foreign()` to create `queuedata`. + // `ForeignOwnable::from_foreign()` is only called when the tagset is + // dropped, which happens after we are dropped. + let queue_data = unsafe { T::QueueData::borrow(queue_data) }; + T::commit_rqs(queue_data) } - /// This function is called by the C kernel. It is not currently - /// implemented, and there is no way to exercise this code path. + /// This function is called by the C kernel. A pointer to this function is + /// installed in the `blk_mq_ops` vtable for the driver. /// /// # Safety /// - /// This function may only be called by blk-mq C infrastructure. - unsafe extern "C" fn complete_callback(_rq: *mut bindings::request) {} + /// This function may only be called by blk-mq C infrastructure. `rq` must + /// point to a valid request that has been marked as completed. The pointee + /// of `rq` must be valid for write for the duration of this function. + unsafe extern "C" fn complete_callback(rq: *mut bindings::request) { + // SAFETY: This function can only be dispatched through + // `Request::complete`. We leaked a refcount then which we pick back up + // now. + let aref = unsafe { Request::aref_from_raw(rq) }; + T::complete(aref); + } /// This function is called by the C kernel. A pointer to this function is /// installed in the `blk_mq_ops` vtable for the driver. @@ -187,7 +227,7 @@ impl<T: Operations> OperationsVTable<T> { // SAFETY: The refcount field is allocated but not initialized, so // it is valid for writes. - unsafe { RequestDataWrapper::refcount_ptr(pdu.as_ptr()).write(AtomicU64::new(0)) }; + unsafe { RequestDataWrapper::refcount_ptr(pdu.as_ptr()).write(Refcount::new(0)) }; Ok(0) }) |