virtq: remove Transfer

Transfer was a wrapper around TransferToken, which in turn is a wrapper around BufferToken with the state of the transfer and the queue which the transfer is to be returned. The receiving queues do not need a reference to themselves and the transfer state is no longer needed as a variable since we do not share the transfer with the caller while the transfer in process. As a result, we are able to replace the uses of Transfer with BufferToken. Most methods on Transfer are also wrappers around the underlying BufferToken and could be removed in entirely. Those that didn't have an exact analogue in the implementation of BufferToken were moved there.

src/drivers/net/virtio_net.rs

@@ -2,6 +2,7 @@
 //!
 //! The module contains ...
 
+use alloc::boxed::Box;
 use alloc::collections::VecDeque;
 use alloc::rc::Rc;
 use alloc::vec::Vec;
@@ -31,9 +32,7 @@ use crate::drivers::virtio::transport::mmio::{ComCfg, IsrStatus, NotifCfg};
 use crate::drivers::virtio::transport::pci::{ComCfg, IsrStatus, NotifCfg};
 use crate::drivers::virtio::virtqueue::packed::PackedVq;
 use crate::drivers::virtio::virtqueue::split::SplitVq;
-use crate::drivers::virtio::virtqueue::{
-	BuffSpec, BufferToken, Bytes, Transfer, Virtq, VqIndex, VqSize,
-};
+use crate::drivers::virtio::virtqueue::{BuffSpec, BufferToken, Bytes, Virtq, VqIndex, VqSize};
 use crate::executor::device::{RxToken, TxToken};
 
 /// A wrapper struct for the raw configuration structure.
@@ -155,14 +154,14 @@ enum MqCmd {
 
 pub struct RxQueues {
 	vqs: Vec<Rc<dyn Virtq>>,
-	poll_queue: Rc<RefCell<VecDeque<Transfer>>>,
+	poll_queue: Rc<RefCell<VecDeque<Box<BufferToken>>>>,
 	is_multi: bool,
 }
 
 impl RxQueues {
 	pub fn new(
 		vqs: Vec<Rc<dyn Virtq>>,
-		poll_queue: Rc<RefCell<VecDeque<Transfer>>>,
+		poll_queue: Rc<RefCell<VecDeque<Box<BufferToken>>>>,
 		is_multi: bool,
 	) -> Self {
 		Self {
@@ -176,14 +175,8 @@ impl RxQueues {
 	/// This currently include nothing. But in the future it might include among others::
 	/// * Calculating missing checksums
 	/// * Merging receive buffers, by simply checking the poll_queue (if VIRTIO_NET_F_MRG_BUF)
-	fn post_processing(transfer: Transfer) -> Result<Transfer, VirtioNetError> {
-		if transfer.poll() {
-			// Here we could implement all features.
-			Ok(transfer)
-		} else {
-			warn!("Unfinished transfer in post processing. Returning buffer to queue. This will need explicit cleanup.");
-			Err(VirtioNetError::ProcessOngoing)
-		}
+	fn post_processing(buffer_tkn: Box<BufferToken>) -> Result<Box<BufferToken>, VirtioNetError> {
+		Ok(buffer_tkn)
 	}
 
 	/// Adds a given queue to the underlying vector and populates the queue with RecvBuffers.
@@ -230,7 +223,7 @@ impl RxQueues {
 		}
 	}
 
-	fn get_next(&mut self) -> Option<Transfer> {
+	fn get_next(&mut self) -> Option<Box<BufferToken>> {
 		let transfer = self.poll_queue.borrow_mut().pop_front();
 
 		transfer.or_else(|| {
@@ -276,7 +269,7 @@ impl RxQueues {
 /// to the respective queue structures.
 pub struct TxQueues {
 	vqs: Vec<Rc<dyn Virtq>>,
-	poll_queue: Rc<RefCell<VecDeque<Transfer>>>,
+	poll_queue: Rc<RefCell<VecDeque<Box<BufferToken>>>>,
 	ready_queue: Vec<BufferToken>,
 	/// Indicates, whether the Driver/Device are using multiple
 	/// queues for communication.
@@ -286,7 +279,7 @@ pub struct TxQueues {
 impl TxQueues {
 	pub fn new(
 		vqs: Vec<Rc<dyn Virtq>>,
-		poll_queue: Rc<RefCell<VecDeque<Transfer>>>,
+		poll_queue: Rc<RefCell<VecDeque<Box<BufferToken>>>>,
 		ready_queue: Vec<BufferToken>,
 		is_multi: bool,
 	) -> Self {
@@ -419,8 +412,8 @@ impl TxQueues {
 			self.poll();
 		}
 
-		while let Some(transfer) = self.poll_queue.borrow_mut().pop_back() {
-			let mut tkn = transfer.reuse().unwrap();
+		while let Some(buffer_token) = self.poll_queue.borrow_mut().pop_back() {
+			let mut tkn = buffer_token.reset();
 			let (send_len, _) = tkn.len();
 
 			match send_len.cmp(&len) {
@@ -586,8 +579,7 @@ impl NetworkDriver for VirtioNetDriver {
 						// drop packets with invalid packet size
 						if packet.len() < HEADER_SIZE {
 							transfer
-								.reuse()
-								.unwrap()
+								.reset()
 								.provide()
 								.dispatch_await(Rc::clone(&self.recv_vqs.poll_queue), false);
 
@@ -604,8 +596,7 @@ impl NetworkDriver for VirtioNetDriver {
 
 						vec_data.extend_from_slice(&packet[mem::size_of::<VirtioNetHdr>()..]);
 						transfer
-							.reuse()
-							.unwrap()
+							.reset()
 							.provide()
 							.dispatch_await(Rc::clone(&self.recv_vqs.poll_queue), false);
 
@@ -627,8 +618,7 @@ impl NetworkDriver for VirtioNetDriver {
 						let packet = recv_data.pop().unwrap();
 						vec_data.extend_from_slice(packet);
 						transfer
-							.reuse()
-							.unwrap()
+							.reset()
 							.provide()
 							.dispatch_await(Rc::clone(&self.recv_vqs.poll_queue), false);
 					}
@@ -637,8 +627,7 @@ impl NetworkDriver for VirtioNetDriver {
 				} else {
 					error!("Empty transfer, or with wrong buffer layout. Reusing and returning error to user-space network driver...");
 					transfer
-						.reuse()
-						.unwrap()
+						.reset()
 						.write_seq(None::<&VirtioNetHdr>, Some(&VirtioNetHdr::default()))
 						.unwrap()
 						.provide()