Make new processes start sleeping

src/interrupts.rs

@@ -188,14 +188,11 @@ fn irq_handler(_stack_frame: InterruptStackFrame, index: u8, _error_code: Option
                 clippy::unwrap_used,
                 reason = "The PID is known valid due to using it in message_queue_mut in the if-let condition"
             )]
-            let sleep_status = TASKING.proc_sleeping(pid).unwrap();
-            if sleep_status == Some(SleepReason::WaitingForIPC) {
-                #[expect(
-                    clippy::unwrap_used,
-                    reason = "The PID is known valid due to using it in message_queue_mut in the if-let condition"
-                )]
-                TASKING.wake(pid).unwrap();
-            }
+            #[expect(
+                clippy::unwrap_used,
+                reason = "The PID is known valid due to using it in message_queue_mut in the if-let condition"
+            )]
+            TASKING.wake(pid, SleepReason::WaitingForIPC).unwrap();
         } else {
             println!("irq 1 msg: Bad PID ({})", pid);
         }
@@ -549,14 +546,11 @@ extern "C" fn syscall_handler() {
                         clippy::unwrap_used,
                         reason = "The PID is known valid due to using it in message_queue_mut in the if-let condition"
                     )]
-                    let sleep_status = TASKING.proc_sleeping(pid).unwrap();
-                    if sleep_status == Some(SleepReason::WaitingForIPC) {
-                        #[expect(
-                            clippy::unwrap_used,
-                            reason = "The PID is known valid due to using it in message_queue_mut in the if-let condition"
-                        )]
-                        TASKING.wake(pid).unwrap();
-                    }
+                    #[expect(
+                        clippy::unwrap_used,
+                        reason = "The PID is known valid due to using it in message_queue_mut in the if-let condition"
+                    )]
+                    TASKING.wake(pid, SleepReason::WaitingForIPC).unwrap();
                     retval = 0;
                 } else {
                     println!("ipc_send: Bad PID ({})", pid);
@@ -752,6 +746,14 @@ extern "C" fn syscall_handler() {
                 retval = 1;
             }
         }
+        24 => {
+            let pid = usize(regs.rcx);
+            if TASKING.wake(pid, SleepReason::NewProcess).is_err() {
+                retval = 1;
+            } else {
+                retval = 0;
+            }
+        }
         _ => (),
     };
     unsafe { SYSCALL_REGS = regs };

src/main.rs

@@ -102,7 +102,7 @@ use physical_memory::PHYSICAL_MEMORY;
 use serial::SECOND_PORT;
 use spin::lazy::Lazy;
 use tar_no_std::TarArchiveRef;
-use tasking::TASKING;
+use tasking::{SleepReason, TASKING};
 use virtual_memory::{ACTIVE_SPACE, KERNEL_SPACE};
 use x86_64::{
     registers::rflags::{self, RFlags},
@@ -290,11 +290,12 @@ pub fn main() {
         clippy::unwrap_used,
         reason = "Argument does not contain a null byte, thus this cannot panic"
     )]
-    TASKING
+    let init_pid = TASKING
         .new_process(
             ptr::with_exposed_provenance(usize(init.ehdr.e_entry)),
             init_addr_space,
             &[&CString::new(b"init").unwrap()],
         )
         .expect("Failed to create init process");
+    TASKING.wake(init_pid, SleepReason::NewProcess).unwrap();
 }

src/tasking.rs

@@ -85,6 +85,7 @@ extern "C" fn task_init() {
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum SleepReason {
     WaitingForIPC,
+    NewProcess,
 }
 
 #[derive(Debug)]
@@ -203,10 +204,10 @@ impl Tasking {
             address_spaces: Mutex::new(Slab::new()),
             data_buffers: Mutex::new(Slab::new()),
             message_queue: Mutex::new(SegQueue::new()),
-            sleeping: RwLock::new(None),
+            sleeping: RwLock::new(Some(SleepReason::NewProcess)),
             arguments: (user_arg_mem.cast(), arguments.len()),
         });
-        self.ready_to_run.lock().push_back(pid);
+        //self.ready_to_run.lock().push_back(pid);
         Ok(pid)
     }
 
@@ -222,63 +223,66 @@ impl Tasking {
     }
 
     pub fn task_yield(&self) {
-        self.freeable_kstacks.lock().clear();
-        let Some(current_pid) = *self.current_pid.read() else {
-            self.wfi_loop.store(false, Ordering::Relaxed);
-            return;
-        };
-        let next_process_pid = self.ready_to_run.lock().pop_front();
-        if let Some(next_process_pid) = next_process_pid {
-            self.wfi_loop.store(false, Ordering::Relaxed);
-            if next_process_pid == self.current_pid().unwrap() {
-                println!("Yielding to currect process! Returning");
-                return;
+        loop {
+            self.freeable_kstacks.lock().clear();
+            let Some(current_pid) = *self.current_pid.read() else {
+                self.wfi_loop.store(false, Ordering::Relaxed);
+                break;
+            };
+            let next_process_pid = self.ready_to_run.lock().pop_front();
+            if let Some(next_process_pid) = next_process_pid {
+                self.wfi_loop.store(false, Ordering::Relaxed);
+                if next_process_pid == self.current_pid().unwrap() {
+                    println!("Yielding to currect process! Returning");
+                    break;
+                }
+                #[expect(
+                    clippy::expect_used,
+                    reason = "This expect checks a critical invariant. If this fails, the kernel MUST panic"
+                )]
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                let current_address_space = self.processes.write()[next_process_pid]
+                    .address_space
+                    .take()
+                    .expect("Non-current process has active page table")
+                    .activate();
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                self.processes.write()[current_pid].address_space = Some(current_address_space);
+                let processes = self.processes.read();
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                let current_process = &processes[current_pid];
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                let next_process = &processes[next_process_pid];
+                gdt::set_tss_stack(next_process.kernel_esp_top);
+                if current_process.sleeping.read().is_none() {
+                    self.ready_to_run.lock().push_back(current_pid);
+                }
+                let kernel_esp = next_process.kernel_esp;
+                let previous_process = current_pid;
+                *self.current_pid.write() = Some(next_process_pid);
+                core::mem::drop(processes);
+                let mut processes = self.processes.write();
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                let curr_stack = addr_of_mut!(processes[previous_process].kernel_esp);
+                core::mem::drop(processes);
+                switch_to_asm(curr_stack, kernel_esp);
+                break;
+            } else if {
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                let res = self.processes.read()[current_pid].sleeping.read().is_some();
+                res
+            } {
+                //println!("All processes sleeping, exiting QEMU");
+                //self.print_stats();
+                //qemu_exit::exit_qemu();
+                //println!("All processes sleeping, waiting for interrupt");
+                self.wfi_loop.store(true, Ordering::Relaxed);
+                x86_64::instructions::interrupts::enable_and_hlt();
+                x86_64::instructions::interrupts::disable();
+            } else {
+                self.wfi_loop.store(false, Ordering::Relaxed);
+                break;
             }
-            #[expect(
-                clippy::expect_used,
-                reason = "This expect checks a critical invariant. If this fails, the kernel MUST panic"
-            )]
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            let current_address_space = self.processes.write()[next_process_pid]
-                .address_space
-                .take()
-                .expect("Non-current process has active page table")
-                .activate();
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            self.processes.write()[current_pid].address_space = Some(current_address_space);
-            let processes = self.processes.read();
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            let current_process = &processes[current_pid];
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            let next_process = &processes[next_process_pid];
-            gdt::set_tss_stack(next_process.kernel_esp_top);
-            if current_process.sleeping.read().is_none() {
-                self.ready_to_run.lock().push_back(current_pid);
-            }
-            let kernel_esp = next_process.kernel_esp;
-            let previous_process = current_pid;
-            *self.current_pid.write() = Some(next_process_pid);
-            core::mem::drop(processes);
-            let mut processes = self.processes.write();
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            let curr_stack = addr_of_mut!(processes[previous_process].kernel_esp);
-            core::mem::drop(processes);
-            switch_to_asm(curr_stack, kernel_esp);
-        } else if {
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            let res = self.processes.read()[current_pid].sleeping.read().is_some();
-            res
-        } {
-            //println!("All processes sleeping, exiting QEMU");
-            //self.print_stats();
-            //qemu_exit::exit_qemu();
-            //println!("All processes sleeping, waiting for interrupt");
-            self.wfi_loop.store(true, Ordering::Relaxed);
-            x86_64::instructions::interrupts::enable_and_hlt();
-            x86_64::instructions::interrupts::disable();
-            self.task_yield();
-        } else {
-            self.wfi_loop.store(false, Ordering::Relaxed);
         }
     }
 
@@ -287,37 +291,39 @@ impl Tasking {
     }
 
     pub fn exit(&self) -> ! {
-        let next_process_pid = self.ready_to_run.lock().pop_front();
-        if let Some(next_process_pid) = next_process_pid {
-            self.wfi_loop.store(false, Ordering::Relaxed);
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            let mut processes = self.processes.write();
-            if let Some(current_pid) = *self.current_pid.read() {
-                self.freeable_kstacks.lock().push(processes.remove(current_pid).kernel_stack);
+        loop {
+            let next_process_pid = self.ready_to_run.lock().pop_front();
+            if let Some(next_process_pid) = next_process_pid {
+                self.wfi_loop.store(false, Ordering::Relaxed);
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                let mut processes = self.processes.write();
+                if let Some(current_pid) = *self.current_pid.read() {
+                    self.freeable_kstacks.lock().push(processes.remove(current_pid).kernel_stack);
+                }
+                #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
+                let next_process = &mut processes[next_process_pid];
+                #[expect(
+                    clippy::expect_used,
+                    reason = "This expect checks a critical invariant. If this fails, the kernel MUST panic"
+                )]
+                next_process
+                    .address_space
+                    .take()
+                    .expect("Non-current process has active page table")
+                    .activate();
+                gdt::set_tss_stack(next_process.kernel_esp_top);
+                let kernel_esp = next_process.kernel_esp;
+                *self.current_pid.write() = Some(next_process_pid);
+                core::mem::drop(processes);
+                switch_to_asm_exit(kernel_esp);
+                unreachable!()
+            } else {
+                //println!("Last non-sleeping process exited, exiting QEMU");
+                self.wfi_loop.store(true, Ordering::Relaxed);
+                x86_64::instructions::interrupts::enable_and_hlt();
+                x86_64::instructions::interrupts::disable();
+                //self.exit();
             }
-            #[warn(clippy::indexing_slicing, reason = "FIXME(?)")]
-            let next_process = &mut processes[next_process_pid];
-            #[expect(
-                clippy::expect_used,
-                reason = "This expect checks a critical invariant. If this fails, the kernel MUST panic"
-            )]
-            next_process
-                .address_space
-                .take()
-                .expect("Non-current process has active page table")
-                .activate();
-            gdt::set_tss_stack(next_process.kernel_esp_top);
-            let kernel_esp = next_process.kernel_esp;
-            *self.current_pid.write() = Some(next_process_pid);
-            core::mem::drop(processes);
-            switch_to_asm_exit(kernel_esp);
-            unreachable!()
-        } else {
-            //println!("Last non-sleeping process exited, exiting QEMU");
-            self.wfi_loop.store(true, Ordering::Relaxed);
-            x86_64::instructions::interrupts::enable_and_hlt();
-            x86_64::instructions::interrupts::disable();
-            self.exit();
         }
     }
 
@@ -389,10 +395,15 @@ impl Tasking {
         self.task_yield();
     }
 
-    pub fn wake(&self, pid: usize) -> Result<(), InvalidPid> {
-        *self.processes.read().get(pid).ok_or(InvalidPid)?.sleeping.write() = None;
-        if Some(pid) != self.current_pid() {
-            self.ready_to_run.lock().push_back(pid);
+    pub fn wake(&self, pid: usize, reason: SleepReason) -> Result<(), InvalidPid> {
+        let processes = self.processes.read();
+        let process = processes.get(pid).ok_or(InvalidPid)?;
+        let mut sleeping = process.sleeping.write();
+        if *sleeping == Some(reason) {
+            if Some(pid) != self.current_pid() {
+                self.ready_to_run.lock().push_back(pid);
+            }
+            *sleeping = None;
         }
         Ok(())
     }