1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155

mod context;
mod id;
mod manager;
mod process;
mod processor;
mod signal;
mod switch;
#[allow(clippy::module_inception)]
mod task;

use self::id::TaskUserRes;
use crate::fs::{open_file, OpenFlags};
use alloc::{sync::Arc, vec::Vec};
use lazy_static::*;
use manager::fetch_task;
use process::ProcessControlBlock;
use switch::__switch;

pub use context::TaskContext;
pub use id::{kstack_alloc, pid_alloc, KernelStack, PidHandle, IDLE_PID};
pub use manager::{add_task, pid2process, remove_from_pid2process};
pub use processor::{
    current_kstack_top, current_process, current_task, current_trap_cx, current_trap_cx_user_va,
    current_user_token, run_tasks, schedule, take_current_task,
};
pub use signal::SignalFlags;
pub use task::{TaskControlBlock, TaskStatus};

pub fn suspend_current_and_run_next() {
    // There must be an application running.
    let task = take_current_task().unwrap();

    // ---- access current TCB exclusively
    let mut task_inner = task.inner_exclusive_access();
    let task_cx_ptr = &mut task_inner.task_cx as *mut TaskContext;
    // Change status to Ready
    task_inner.task_status = TaskStatus::Ready;
    drop(task_inner);
    // ---- release current TCB

    // push back to ready queue.
    add_task(task);
    // jump to scheduling cycle
    schedule(task_cx_ptr);
}

/// This function must be followed by a schedule
pub fn block_current_task() -> *mut TaskContext {
    let task = take_current_task().unwrap();
    let mut task_inner = task.inner_exclusive_access();
    task_inner.task_status = TaskStatus::Blocking;
    &mut task_inner.task_cx as *mut TaskContext
}

pub fn block_current_and_run_next() {
    let task_cx_ptr = block_current_task();
    schedule(task_cx_ptr);
}

pub fn exit_current_and_run_next(exit_code: i32) {
    let task = take_current_task().unwrap();
    let mut task_inner = task.inner_exclusive_access();
    let process = task.process.upgrade().unwrap();
    let tid = task_inner.res.as_ref().unwrap().tid;
    // record exit code
    task_inner.exit_code = Some(exit_code);
    task_inner.res = None;
    // here we do not remove the thread since we are still using the kstack
    // it will be deallocated when sys_waittid is called
    drop(task_inner);
    drop(task);
    // however, if this is the main thread of current process
    // the process should terminate at once
    if tid == 0 {
        let pid = process.getpid();
        if pid == IDLE_PID {
            println!(
                "[kernel] Idle process exit with exit_code {} ...",
                exit_code
            );
            if exit_code != 0 {
                crate::sbi::shutdown(255); //255 == -1 for err hint
            } else {
                crate::sbi::shutdown(0); //0 for success hint
            }
        }
        remove_from_pid2process(pid);
        let mut process_inner = process.inner_exclusive_access();
        // mark this process as a zombie process
        process_inner.is_zombie = true;
        // record exit code of main process
        process_inner.exit_code = exit_code;

        {
            // move all child processes under init process
            let mut initproc_inner = INITPROC.inner_exclusive_access();
            for child in process_inner.children.iter() {
                child.inner_exclusive_access().parent = Some(Arc::downgrade(&INITPROC));
                initproc_inner.children.push(child.clone());
            }
        }

        // deallocate user res (including tid/trap_cx/ustack) of all threads
        // it has to be done before we dealloc the whole memory_set
        // otherwise they will be deallocated twice
        let mut recycle_res = Vec::<TaskUserRes>::new();
        for task in process_inner.tasks.iter().filter(|t| t.is_some()) {
            let task = task.as_ref().unwrap();
            let mut task_inner = task.inner_exclusive_access();
            if let Some(res) = task_inner.res.take() {
                recycle_res.push(res);
            }
        }
        // dealloc_tid and dealloc_user_res require access to PCB inner, so we
        // need to collect those user res first, then release process_inner
        // for now to avoid deadlock/double borrow problem.
        drop(process_inner);
        recycle_res.clear();

        let mut process_inner = process.inner_exclusive_access();
        process_inner.children.clear();
        // deallocate other data in user space i.e. program code/data section
        process_inner.memory_set.recycle_data_pages();
        // drop file descriptors
        process_inner.fd_table.clear();
    }
    drop(process);
    // we do not have to save task context
    let mut _unused = TaskContext::zero_init();
    schedule(&mut _unused as *mut _);
}

lazy_static! {
    pub static ref INITPROC: Arc<ProcessControlBlock> = {
        let inode = open_file("initproc", OpenFlags::RDONLY).unwrap();
        let v = inode.read_all();
        ProcessControlBlock::new(v.as_slice())
    };
}

pub fn add_initproc() {
    let _initproc = INITPROC.clone();
}

pub fn check_signals_of_current() -> Option<(i32, &'static str)> {
    let process = current_process();
    let process_inner = process.inner_exclusive_access();
    process_inner.signals.check_error()
}

pub fn current_add_signal(signal: SignalFlags) {
    let process = current_process();
    let mut process_inner = process.inner_exclusive_access();
    process_inner.signals |= signal;
}