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Kernel: Get rid of "main thread" concept

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The idea of all processes reliably having a main thread was nice in
some ways, but cumbersome in others. More importantly, it didn't match
up with POSIX thread semantics, so let's move away from it.

This thread gets rid of Process::main_thread() and you now we just have
a bunch of Thread objects floating around each Process.

When the finalizer nukes the last Thread in a Process, it will also
tear down the Process.

There's a bunch of more things to fix around this, but this is where we
get started :^)
This commit is contained in:
Andreas Kling 2019-12-22 11:35:02 +01:00
parent 150837e7e8
commit 16812f0f98
Notes: sideshowbarker 2024-07-19 10:46:27 +09:00
6 changed files with 123 additions and 113 deletions
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17
Kernel/Scheduler.cpp
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@ -47,6 +47,7 @@ static u32 time_slice_for(ThreadPriority priority)
Thread* current;
Thread* g_last_fpu_thread;
Thread* g_finalizer;
Thread* g_colonel;
WaitQueue* g_finalizer_wait_queue;
static Process* s_colonel_process;
u64 g_uptime;
@ -222,7 +223,7 @@ bool Thread::WaitBlocker::should_unblock(Thread& thread, time_t, long)
return IterationDecision::Continue;
bool child_exited = child.is_dead();
bool child_stopped = child.main_thread().state() == Thread::State::Stopped;
bool child_stopped = child.thread_count() && child.any_thread().state() == Thread::State::Stopped;
bool wait_finished = ((m_wait_options & WEXITED) && child_exited)
|| ((m_wait_options & WSTOPPED) && child_stopped);
@ -288,7 +289,7 @@ bool Scheduler::pick_next()
if (!current) {
// XXX: The first ever context_switch() goes to the idle process.
// This to setup a reliable place we can return to.
return context_switch(s_colonel_process->main_thread());
return context_switch(*g_colonel);
}
struct timeval now;
@ -305,7 +306,7 @@ bool Scheduler::pick_next()
Process::for_each([&](Process& process) {
if (process.is_dead()) {
if (current != &process.main_thread() && (!process.ppid() || !Process::from_pid(process.ppid()))) {
if (current->pid() != process.pid() && (!process.ppid() || !Process::from_pid(process.ppid()))) {
auto name = process.name();
auto pid = process.pid();
auto exit_status = Process::reap(process);
@ -369,7 +370,7 @@ bool Scheduler::pick_next()
auto& runnable_list = g_scheduler_data->m_runnable_threads;
if (runnable_list.is_empty())
return context_switch(s_colonel_process->main_thread());
return context_switch(*g_colonel);
auto* previous_head = runnable_list.first();
for (;;) {
@ -386,7 +387,7 @@ bool Scheduler::pick_next()
if (thread == previous_head) {
// Back at process_head, nothing wants to run. Send in the colonel!
return context_switch(s_colonel_process->main_thread());
return context_switch(*g_colonel);
}
}
}
@ -535,9 +536,9 @@ void Scheduler::initialize()
g_finalizer_wait_queue = new WaitQueue;
s_redirection.selector = gdt_alloc_entry();
initialize_redirection();
s_colonel_process = Process::create_kernel_process("colonel", nullptr);
s_colonel_process = Process::create_kernel_process(g_colonel, "colonel", nullptr);
// Make sure the colonel uses a smallish time slice.
s_colonel_process->main_thread().set_priority(ThreadPriority::Idle);
g_colonel->set_priority(ThreadPriority::Idle);
load_task_register(s_redirection.selector);
}
@ -614,7 +615,7 @@ static bool s_should_stop_idling = false;
void Scheduler::stop_idling()
{
if (current != &s_colonel_process->main_thread())
if (current != g_colonel)
return;
s_should_stop_idling = true;