task: better async error handling

src/device/nvme/error.rs

@@ -0,0 +1,15 @@
+use abi::error::Error;
+
+use super::queue::CommandError;
+
+#[derive(Debug)]
+pub enum NvmeError {
+    MemoryError(Error),
+    CommandError(CommandError),
+}
+
+impl From<CommandError> for NvmeError {
+    fn from(value: CommandError) -> Self {
+        Self::CommandError(value)
+    }
+}

src/device/nvme/mod.rs

@@ -29,12 +29,14 @@ use crate::{
 
 use self::{
     command::{CreateIoCompletionQueue, CreateIoSubmissionQueue, SetFeatureRequest},
+    error::NvmeError,
     queue::QueuePair,
 };
 
 use super::bus::pci::{FromPciBus, PciDeviceInfo};
 
 mod command;
+mod error;
 mod queue;
 
 register_bitfields! {
@@ -120,29 +122,23 @@ impl Regs {
 }
 
 impl NvmeController {
-    async fn late_init(&'static self) {
+    async fn late_init(&'static self) -> Result<(), NvmeError> {
-        // let ioq = QueuePair::new(capacity, sq_doorbell, cq_doorbell).unwrap();
-
         runtime::spawn(self.poll_task()).expect("Couldn't spawn NVMe poll task");
         let admin_q = self.admin_q.get();
 
         // Request a CQ/SQ pair for I/O
         admin_q
             .request_no_data(SetFeatureRequest::NumberOfQueues(1, 1))
-            .unwrap()
+            .await?;
-            .await
-            .unwrap();
 
         // Allocate the queue
         let (sq_doorbell, cq_doorbell) = unsafe { self.doorbell_pair(1) };
-        let io_q = QueuePair::new(32, sq_doorbell, cq_doorbell).unwrap();
+        let io_q = QueuePair::new(32, sq_doorbell, cq_doorbell).map_err(NvmeError::MemoryError)?;
 
         // Identify the controller
         let identify = admin_q
-            .request(IdentifyControllerRequest { nsid: 0 })
+            .request(IdentifyControllerRequest { nsid: 0 })?
-            .unwrap()
+            .await?;
-            .await
-            .unwrap();
 
         // Create the queue on the device side
         admin_q
@@ -151,9 +147,7 @@ impl NvmeController {
                 size: 32,
                 data: io_q.cq_physical_pointer(),
             })
-            .unwrap()
+            .await?;
-            .await
-            .unwrap();
         admin_q
             .request_no_data(CreateIoSubmissionQueue {
                 id: 1,
@@ -161,9 +155,7 @@ impl NvmeController {
                 size: 32,
                 data: io_q.sq_physical_pointer(),
             })
-            .unwrap()
+            .await?;
-            .await
-            .unwrap();
 
         loop {}
     }

src/device/nvme/queue.rs

@@ -22,7 +22,10 @@ use crate::{
     task::runtime::QueueWaker,
 };
 
-use super::command::{Command, Request};
+use super::{
+    command::{Command, Request},
+    error::NvmeError,
+};
 
 #[derive(Zeroable, Pod, Clone, Copy, Debug)]
 #[repr(C)]
@@ -338,12 +341,7 @@ impl<'a> QueuePair<'a> {
         }
     }
 
-    pub fn submit<C: Command>(
+    pub fn submit<C: Command>(&self, cmd: C, ranges: &[PhysicalAddress], set_pending: bool) -> u32 {
-        &self,
-        cmd: C,
-        ranges: &[PhysicalAddress],
-        set_pending: bool,
-    ) -> Result<u32, Error> {
         let mut inner = self.inner.lock();
         let mut sqe = SubmissionQueueEntry::zeroed();
 
@@ -370,24 +368,27 @@ impl<'a> QueuePair<'a> {
 
         inner.sq.enqueue(sqe);
 
-        Ok(command_id)
+        command_id
     }
 
     pub fn request_no_data<'r, C: Command>(
         &'r self,
         req: C,
-    ) -> Result<impl Future<Output = Result<(), CommandError>> + 'r, Error>
+    ) -> impl Future<Output = Result<(), CommandError>> + 'r
     where
         'r: 'a,
     {
-        let command_id = self.submit(req, &[], true)?;
+        let command_id = self.submit(req, &[], true);
-        Ok(self.wait_for_completion(command_id, ()))
+        self.wait_for_completion(command_id, ())
     }
 
     pub fn request<'r, R: Request>(
         &'r self,
         req: R,
-    ) -> Result<impl Future<Output = Result<PhysicalRefMut<'r, R::Response>, CommandError>>, Error>
+    ) -> Result<
+        impl Future<Output = Result<PhysicalRefMut<'r, R::Response>, CommandError>>,
+        NvmeError,
+    >
     where
         R::Response: 'r,
         'r: 'a,
@@ -395,11 +396,11 @@ impl<'a> QueuePair<'a> {
         assert_ne!(size_of::<R::Response>(), 0);
         assert!(size_of::<R::Response>() < 0x1000);
 
-        let page = phys::alloc_page()?;
+        let page = phys::alloc_page().map_err(NvmeError::MemoryError)?;
         // TODO PageBox
         let response = unsafe { PhysicalRefMut::map(page) };
 
-        let command_id = self.submit(req, &[page], true)?;
+        let command_id = self.submit(req, &[page], true);
         Ok(self.wait_for_completion(command_id, response))
     }
 

src/task/runtime/executor.rs

@@ -7,7 +7,7 @@ use futures_util::{task::waker_ref, Future};
 use crate::task::{spawn_kernel_closure, thread::Thread};
 
 use super::{
-    task::Task,
+    task::{Task, Termination},
     task_queue::{self},
 };
 
@@ -38,7 +38,9 @@ pub fn spawn_async_worker(index: usize) -> Result<(), Error> {
 }
 
 /// Creates a new task for the [Future] and queues it for execution in background
-pub fn spawn<F: Future<Output = ()> + Send + 'static>(future: F) -> Result<(), Error> {
+pub fn spawn<T: Termination, F: Future<Output = T> + Send + 'static>(
+    future: F,
+) -> Result<(), Error> {
     enqueue(Task::new(future))
 }
 

src/task/runtime/task.rs

@@ -1,9 +1,15 @@
+use core::fmt;
+
 use alloc::sync::Arc;
 use futures_util::{future::BoxFuture, task::ArcWake, Future, FutureExt};
 use kernel_util::sync::IrqSafeSpinlock;
 
 use super::executor;
 
+pub trait Termination {
+    fn print(&self);
+}
+
 pub struct Task {
     pub(super) future: IrqSafeSpinlock<Option<BoxFuture<'static, ()>>>,
 }
@@ -15,8 +21,25 @@ impl ArcWake for Task {
 }
 
 impl Task {
-    pub fn new<F: Future<Output = ()> + Send + 'static>(future: F) -> Arc<Self> {
+    pub fn new<T: Termination, F: Future<Output = T> + Send + 'static>(future: F) -> Arc<Self> {
-        let future = IrqSafeSpinlock::new(Some(future.boxed()));
+        let future = IrqSafeSpinlock::new(Some(
+            async move {
+                future.await.print();
+            }
+            .boxed(),
+        ));
         Arc::new(Self { future })
     }
 }
+
+impl Termination for () {
+    fn print(&self) {}
+}
+
+impl<T, E: fmt::Debug> Termination for Result<T, E> {
+    fn print(&self) {
+        if let Err(error) = self {
+            errorln!("A task finished with an error: {:?}", error);
+        }
+    }
+}