Merge pull request #799 from stlankes/async

revise handling of asynchronous tasks

Cargo.toml

@@ -57,8 +57,6 @@ smp = ["include-transformed"]
 fsgsbase = []
 trace = []
 tcp = [
-    "async-task",
-    "futures-lite",
     "smoltcp",
 ]
 dhcpv4 = [
@@ -85,8 +83,6 @@ pflock = "0.2"
 shell-words = { version = "1.1", default-features = false }
 qemu-exit = "3.0"
 rand_chacha = { version = "0.3", default-features = false }
-futures-lite = { version = "1.11", default-features = false, optional = true }
-async-task = { version = "4.4", default-features = false, optional = true }
 lock_api = "0.4"
 num = { version = "0.4", default-features = false }
 num-traits = { version = "0.2", default-features = false }

src/arch/aarch64/kernel/core_local.rs

@@ -1,21 +1,25 @@
 use alloc::boxed::Box;
+use alloc::vec::Vec;
 use core::arch::asm;
-use core::cell::Cell;
+use core::cell::{Cell, RefCell, RefMut};
 use core::ptr;
 use core::sync::atomic::Ordering;
 
 use super::interrupts::{IrqStatistics, IRQ_COUNTERS};
 use super::CPU_ONLINE;
+use crate::executor::task::AsyncTask;
 use crate::scheduler::{CoreId, PerCoreScheduler};
 
-pub struct CoreLocal {
+pub(crate) struct CoreLocal {
 	this: *const Self,
 	/// ID of the current Core.
 	core_id: CoreId,
 	/// Scheduler of the current Core.
 	scheduler: Cell<*mut PerCoreScheduler>,
 	/// Interface to the interrupt counters
 	irq_statistics: &'static IrqStatistics,
+	/// Queue of async tasks
+	async_tasks: RefCell<Vec<AsyncTask>>,
 }
 
 impl CoreLocal {
@@ -30,6 +34,7 @@ impl CoreLocal {
 			core_id,
 			scheduler: Cell::new(ptr::null_mut()),
 			irq_statistics,
+			async_tasks: RefCell::new(Vec::new()),
 		};
 		let this = Box::leak(Box::new(this));
 		this.this = &*this;
@@ -50,7 +55,7 @@ impl CoreLocal {
 }
 
 #[inline]
-pub fn core_id() -> CoreId {
+pub(crate) fn core_id() -> CoreId {
 	if cfg!(target_os = "none") {
 		CoreLocal::get().core_id
 	} else {
@@ -59,14 +64,18 @@ pub fn core_id() -> CoreId {
 }
 
 #[inline]
-pub fn core_scheduler() -> &'static mut PerCoreScheduler {
+pub(crate) fn core_scheduler() -> &'static mut PerCoreScheduler {
 	unsafe { &mut *CoreLocal::get().scheduler.get() }
 }
 
-pub fn set_core_scheduler(scheduler: *mut PerCoreScheduler) {
+pub(crate) fn async_tasks() -> RefMut<'static, Vec<AsyncTask>> {
+	CoreLocal::get().async_tasks.borrow_mut()
+}
+
+pub(crate) fn set_core_scheduler(scheduler: *mut PerCoreScheduler) {
 	CoreLocal::get().scheduler.set(scheduler);
 }
 
-pub fn increment_irq_counter(irq_no: u8) {
+pub(crate) fn increment_irq_counter(irq_no: u8) {
 	CoreLocal::get().irq_statistics.inc(irq_no);
 }

src/arch/x86_64/kernel/core_local.rs

@@ -1,6 +1,7 @@
 use alloc::boxed::Box;
+use alloc::vec::Vec;
 use core::arch::asm;
-use core::cell::Cell;
+use core::cell::{Cell, RefCell, RefMut};
 use core::ptr;
 use core::sync::atomic::Ordering;
 
@@ -10,10 +11,11 @@ use x86_64::VirtAddr;
 
 use super::interrupts::{IrqStatistics, IRQ_COUNTERS};
 use super::CPU_ONLINE;
+use crate::executor::task::AsyncTask;
 use crate::scheduler::{CoreId, PerCoreScheduler};
 
 #[repr(C)]
-pub struct CoreLocal {
+pub(crate) struct CoreLocal {
 	this: *const Self,
 	/// Sequential ID of this CPU Core.
 	core_id: CoreId,
@@ -25,6 +27,8 @@ pub struct CoreLocal {
 	pub kernel_stack: Cell<u64>,
 	/// Interface to the interrupt counters
 	irq_statistics: &'static IrqStatistics,
+	/// Queue of async tasks
+	async_tasks: RefCell<Vec<AsyncTask>>,
 }
 
 impl CoreLocal {
@@ -43,13 +47,15 @@ impl CoreLocal {
 			tss: Cell::new(ptr::null_mut()),
 			kernel_stack: Cell::new(0),
 			irq_statistics,
+			async_tasks: RefCell::new(Vec::new()),
 		};
 		let this = Box::leak(Box::new(this));
 		this.this = &*this;
 
 		GsBase::write(VirtAddr::from_ptr(this));
 	}
 
+	#[inline]
 	pub fn get() -> &'static Self {
 		debug_assert_ne!(VirtAddr::zero(), GsBase::read());
 		unsafe {
@@ -60,22 +66,26 @@ impl CoreLocal {
 	}
 }
 
-pub fn core_id() -> CoreId {
+pub(crate) fn core_id() -> CoreId {
 	if cfg!(target_os = "none") {
 		CoreLocal::get().core_id
 	} else {
 		0
 	}
 }
 
-pub fn core_scheduler() -> &'static mut PerCoreScheduler {
+pub(crate) fn core_scheduler() -> &'static mut PerCoreScheduler {
 	unsafe { &mut *CoreLocal::get().scheduler.get() }
 }
 
-pub fn set_core_scheduler(scheduler: *mut PerCoreScheduler) {
+pub(crate) fn async_tasks() -> RefMut<'static, Vec<AsyncTask>> {
+	CoreLocal::get().async_tasks.borrow_mut()
+}
+
+pub(crate) fn set_core_scheduler(scheduler: *mut PerCoreScheduler) {
 	CoreLocal::get().scheduler.set(scheduler);
 }
 
-pub fn increment_irq_counter(irq_no: u8) {
+pub(crate) fn increment_irq_counter(irq_no: u8) {
 	CoreLocal::get().irq_statistics.inc(irq_no);
 }

src/drivers/net/mod.rs

@@ -47,37 +47,30 @@ pub trait NetworkInterface {
 
 #[inline]
 fn _irqhandler() -> bool {
-	if let Some(driver) = hardware::get_network_driver() {
+	let result = if let Some(driver) = hardware::get_network_driver() {
 		driver.lock().handle_interrupt()
 	} else {
 		debug!("Unable to handle interrupt!");
 		false
-	}
+	};
+
+	// TODO: do we need it?
+	crate::executor::run();
+
+	result
 }
 
 #[cfg(target_arch = "aarch64")]
 pub(crate) fn network_irqhandler(_state: &State) -> bool {
 	debug!("Receive network interrupt");
-	let has_packet = _irqhandler();
-
-	if has_packet {
-		#[cfg(feature = "tcp")]
-		core_scheduler().wakeup_async_tasks();
-	}
-
-	has_packet
+	_irqhandler()
 }
 
 #[cfg(target_arch = "x86_64")]
 pub(crate) extern "x86-interrupt" fn network_irqhandler(_stack_frame: ExceptionStackFrame) {
 	debug!("Receive network interrupt");
 	apic::eoi();
-	let has_packet = _irqhandler();
+	let _ = _irqhandler();
 
-	if has_packet {
-		let core_scheduler = core_scheduler();
-		#[cfg(feature = "tcp")]
-		core_scheduler.wakeup_async_tasks();
-		core_scheduler.reschedule();
-	}
+	core_scheduler().reschedule();
 }

src/drivers/net/virtio_net.rs

@@ -10,6 +10,7 @@ use core::cell::RefCell;
 use core::cmp::Ordering;
 use core::mem;
 use core::result::Result;
+use core::str::FromStr;
 
 use pci_types::InterruptLine;
 use zerocopy::AsBytes;
@@ -517,7 +518,13 @@ impl NetworkInterface for VirtioNetDriver {
 	/// Currently, if VIRTIO_NET_F_MAC is not set
 	//  MTU is set static to 1500 bytes.
 	fn get_mtu(&self) -> u16 {
-		if self.dev_cfg.features.is_feature(Features::VIRTIO_NET_F_MTU) {
+		if let Some(my_mtu) = hermit_var!("HERMIT_MTU") {
+			warn!(
+				"Using value of the environment variable HERMIT_MTU ({}) as MTU",
+				my_mtu
+			);
+			u16::from_str(&my_mtu).unwrap()
+		} else if self.dev_cfg.features.is_feature(Features::VIRTIO_NET_F_MTU) {
 			self.dev_cfg.raw.get_mtu()
 		} else {
 			1500

src/env.rs

@@ -108,7 +108,6 @@ pub fn freq() -> Option<u16> {
 	CLI.get().unwrap().freq
 }
 
-#[cfg(all(feature = "tcp", not(feature = "dhcpv4")))]
 pub fn var(key: &str) -> Option<&String> {
 	CLI.get().unwrap().env_vars.get(key)
 }

src/executor/device.rs

@@ -13,14 +13,12 @@ use smoltcp::wire::{EthernetAddress, HardwareAddress};
 #[cfg(not(feature = "dhcpv4"))]
 use smoltcp::wire::{IpAddress, IpCidr, Ipv4Address};
 
+use super::network::{NetworkInterface, NetworkState};
 use crate::arch;
 #[cfg(not(feature = "pci"))]
 use crate::arch::kernel::mmio as hardware;
 #[cfg(feature = "pci")]
 use crate::drivers::pci as hardware;
-#[cfg(not(feature = "dhcpv4"))]
-use crate::env;
-use crate::executor::{NetworkInterface, NetworkState};
 
 /// Data type to determine the mac address
 #[derive(Debug, Copy, Clone)]
@@ -35,33 +33,6 @@ impl HermitNet {
 	}
 }
 
-/// Returns the value of the specified environment variable.
-///
-/// The value is fetched from the current runtime environment and, if not
-/// present, falls back to the same environment variable set at compile time
-/// (might not be present as well).
-#[cfg(not(feature = "dhcpv4"))]
-macro_rules! hermit_var {
-	($name:expr) => {{
-		use alloc::borrow::Cow;
-
-		match env::var($name) {
-			Some(val) => Some(Cow::from(val)),
-			None => option_env!($name).map(Cow::Borrowed),
-		}
-	}};
-}
-
-/// Tries to fetch the specified environment variable with a default value.
-///
-/// Fetches according to [`hermit_var`] or returns the specified default value.
-#[cfg(not(feature = "dhcpv4"))]
-macro_rules! hermit_var_or {
-	($name:expr, $default:expr) => {{
-		hermit_var!($name).as_deref().unwrap_or($default)
-	}};
-}
-
 impl<'a> NetworkInterface<'a> {
 	#[cfg(feature = "dhcpv4")]
 	pub(crate) fn create() -> NetworkState<'a> {
@@ -89,7 +60,7 @@ impl<'a> NetworkInterface<'a> {
 			config.hardware_addr = hardware_addr;
 		}
 
-		let iface = Interface::new(config, &mut device, crate::executor::now());
+		let iface = Interface::new(config, &mut device, crate::executor::network::now());
 		let mut sockets = SocketSet::new(vec![]);
 		let dhcp_handle = sockets.add(dhcp);
 
@@ -154,7 +125,7 @@ impl<'a> NetworkInterface<'a> {
 			config.hardware_addr = hardware_addr;
 		}
 
-		let mut iface = Interface::new(config, &mut device, crate::executor::now());
+		let mut iface = Interface::new(config, &mut device, crate::executor::network::now());
 		iface.update_ip_addrs(|ip_addrs| {
 			ip_addrs
 				.push(IpCidr::new(