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Kernel: Remove ProcessInspectionHandle and make Process RefCounted

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By making the Process class RefCounted we don't really need
ProcessInspectionHandle anymore. This also fixes some race
conditions where a Process may be deleted while still being
used by ProcFS.

Also make sure to acquire the Process' lock when accessing
regions.

Last but not least, there's no reason why a thread can't be
scheduled while being inspected, though in practice it won't
happen anyway because the scheduler lock is held at the same
time.
This commit is contained in:
Tom 2020-08-01 20:04:56 -06:00 • committed by Andreas Kling
parent 5bbf6ed46b
commit 538b985487
13 changed files with 191 additions and 273 deletions
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12
Kernel/Scheduler.cpp
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@ -66,6 +66,7 @@ void Scheduler::update_state_for_thread(Thread& thread)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(g_scheduler_data);
ASSERT(g_scheduler_lock.own_lock());
auto& list = g_scheduler_data->thread_list_for_state(thread.state());
if (list.contains(thread))
@ -255,7 +256,7 @@ bool Thread::WaitBlocker::should_unblock(Thread& thread, time_t, long)
{
bool should_unblock = m_wait_options & WNOHANG;
if (m_waitee_pid != -1) {
auto* peer = Process::from_pid(m_waitee_pid);
auto peer = Process::from_pid(m_waitee_pid);
if (!peer)
return true;
}
@ -458,9 +459,6 @@ bool Scheduler::pick_next()
Thread* thread_to_schedule = nullptr;
for (auto* thread : sorted_runnables) {
if (thread->process().is_being_inspected())
continue;
if (thread->process().exec_tid() && thread->process().exec_tid() != thread->tid())
continue;
@ -516,6 +514,8 @@ bool Scheduler::yield()
bool Scheduler::donate_to(Thread* beneficiary, const char* reason)
{
ASSERT(beneficiary);
// Set the m_in_scheduler flag before acquiring the spinlock. This
// prevents a recursive call into Scheduler::invoke_async upon
// leaving the scheduler lock.
@ -534,8 +534,6 @@ bool Scheduler::donate_to(Thread* beneficiary, const char* reason)
ScopedSpinLock lock(g_scheduler_lock);
ASSERT(!proc.in_irq());
if (!Thread::is_thread(beneficiary))
return false;
if (proc.in_critical()) {
proc.invoke_scheduler_async();
@ -660,7 +658,7 @@ void Scheduler::initialize()
g_finalizer_wait_queue = new WaitQueue;
g_finalizer_has_work.store(false, AK::MemoryOrder::memory_order_release);
s_colonel_process = Process::create_kernel_process(idle_thread, "colonel", idle_loop, 1);
s_colonel_process = &Process::create_kernel_process(idle_thread, "colonel", idle_loop, 1).leak_ref();
ASSERT(s_colonel_process);
ASSERT(idle_thread);
idle_thread->set_priority(THREAD_PRIORITY_MIN);