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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/QuickSort.h>
#include <AK/ScopeGuard.h>
#include <AK/TemporaryChange.h>
#include <AK/Time.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Net/Socket.h>
#include <Kernel/Process.h>
#include <Kernel/Profiling.h>
#include <Kernel/RTC.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Time/TimeManagement.h>
#include <Kernel/TimerQueue.h>
//#define LOG_EVERY_CONTEXT_SWITCH
//#define SCHEDULER_DEBUG
//#define SCHEDULER_RUNNABLE_DEBUG
namespace Kernel {
class SchedulerPerProcessorData {
AK_MAKE_NONCOPYABLE(SchedulerPerProcessorData);
AK_MAKE_NONMOVABLE(SchedulerPerProcessorData);
public:
SchedulerPerProcessorData() = default;
Thread* m_pending_beneficiary { nullptr };
const char* m_pending_donate_reason { nullptr };
bool m_in_scheduler { true };
};
SchedulerData* g_scheduler_data;
timeval g_timeofday;
RecursiveSpinLock g_scheduler_lock;
void Scheduler::init_thread(Thread& thread)
{
ASSERT(g_scheduler_data);
g_scheduler_data->m_nonrunnable_threads.append(thread);
}
static u32 time_slice_for(const Thread& thread)
{
// One time slice unit == 1ms
if (&thread == Processor::current().idle_thread())
return 1;
return 10;
}
timeval Scheduler::time_since_boot()
{
return { TimeManagement::the().seconds_since_boot(), (suseconds_t)TimeManagement::the().ticks_this_second() * 1000 };
}
Thread* g_finalizer;
WaitQueue* g_finalizer_wait_queue;
Atomic<bool> g_finalizer_has_work { false };
static Process* s_colonel_process;
u64 g_uptime;
Thread::JoinBlocker::JoinBlocker(Thread& joinee, KResult& try_join_result, void*& joinee_exit_value)
: m_joinee(&joinee)
, m_joinee_exit_value(joinee_exit_value)
{
auto* current_thread = Thread::current();
// We need to hold our lock to avoid a race where try_join succeeds
// but the joinee is joining immediately
ScopedSpinLock lock(m_lock);
try_join_result = joinee.try_join(*current_thread);
m_join_error = try_join_result.is_error();
}
void Thread::JoinBlocker::was_unblocked()
{
ScopedSpinLock lock(m_lock);
if (!m_join_error && m_joinee) {
// If the joinee hasn't exited yet, remove ourselves now
ASSERT(m_joinee != Thread::current());
m_joinee->join_done();
m_joinee = nullptr;
}
}
bool Thread::JoinBlocker::should_unblock(Thread&)
{
// We need to acquire our lock as the joinee could call joinee_exited
// at any moment
ScopedSpinLock lock(m_lock);
if (m_join_error) {
// Thread::block calls should_unblock before actually blocking.
// If detected that we can't really block due to an error, we'll
// return true here, which will cause Thread::block to return
// with BlockResult::NotBlocked. Technically, because m_join_error
// will only be set in the constructor, we don't need any lock
// to check for it, but at the same time there should not be
// any contention, either...
return true;
}
return m_joinee == nullptr;
}
void Thread::JoinBlocker::joinee_exited(void* value)
{
ScopedSpinLock lock(m_lock);
if (!m_joinee) {
// m_joinee can be nullptr if the joiner timed out and the
// joinee waits on m_lock while the joiner holds it but has
// not yet called join_done.
return;
}
m_joinee_exit_value = value;
m_joinee = nullptr;
set_interrupted_by_death();
}
Thread::FileDescriptionBlocker::FileDescriptionBlocker(const FileDescription& description)
: m_blocked_description(description)
{
}
const FileDescription& Thread::FileDescriptionBlocker::blocked_description() const
{
return m_blocked_description;
}
Thread::AcceptBlocker::AcceptBlocker(const FileDescription& description)
: FileDescriptionBlocker(description)
{
}
bool Thread::AcceptBlocker::should_unblock(Thread&)
{
auto& socket = *blocked_description().socket();
return socket.can_accept();
}
Thread::ConnectBlocker::ConnectBlocker(const FileDescription& description)
: FileDescriptionBlocker(description)
{
}
bool Thread::ConnectBlocker::should_unblock(Thread&)
{
auto& socket = *blocked_description().socket();
return socket.setup_state() == Socket::SetupState::Completed;
}
Thread::WriteBlocker::WriteBlocker(const FileDescription& description)
: FileDescriptionBlocker(description)
{
}
timespec* Thread::WriteBlocker::override_timeout(timespec* timeout)
{
auto& description = blocked_description();
if (description.is_socket()) {
auto& socket = *description.socket();
if (socket.has_send_timeout()) {
timeval_to_timespec(Scheduler::time_since_boot(), m_deadline);
timespec_add_timeval(m_deadline, socket.send_timeout(), m_deadline);
if (!timeout || m_deadline < *timeout)
return &m_deadline;
}
}
return timeout;
}
bool Thread::WriteBlocker::should_unblock(Thread&)
{
return blocked_description().can_write();
}
Thread::ReadBlocker::ReadBlocker(const FileDescription& description)
: FileDescriptionBlocker(description)
{
}
timespec* Thread::ReadBlocker::override_timeout(timespec* timeout)
{
auto& description = blocked_description();
if (description.is_socket()) {
auto& socket = *description.socket();
if (socket.has_receive_timeout()) {
timeval_to_timespec(Scheduler::time_since_boot(), m_deadline);
timespec_add_timeval(m_deadline, socket.receive_timeout(), m_deadline);
if (!timeout || m_deadline < *timeout)
return &m_deadline;
}
}
return timeout;
}
bool Thread::ReadBlocker::should_unblock(Thread&)
{
return blocked_description().can_read();
}
Thread::ConditionBlocker::ConditionBlocker(const char* state_string, Function<bool()>&& condition)
: m_block_until_condition(move(condition))
, m_state_string(state_string)
{
ASSERT(m_block_until_condition);
}
bool Thread::ConditionBlocker::should_unblock(Thread&)
{
return m_block_until_condition();
}
Thread::SleepBlocker::SleepBlocker(u64 wakeup_time)
: m_wakeup_time(wakeup_time)
{
}
bool Thread::SleepBlocker::should_unblock(Thread&)
{
return m_wakeup_time <= g_uptime;
}
Thread::SelectBlocker::SelectBlocker(const FDVector& read_fds, const FDVector& write_fds, const FDVector& except_fds)
: m_select_read_fds(read_fds)
, m_select_write_fds(write_fds)
, m_select_exceptional_fds(except_fds)
{
}
bool Thread::SelectBlocker::should_unblock(Thread& thread)
{
auto& process = thread.process();
for (int fd : m_select_read_fds) {
if (!process.m_fds[fd])
continue;
if (process.m_fds[fd].description()->can_read())
return true;
}
for (int fd : m_select_write_fds) {
if (!process.m_fds[fd])
continue;
if (process.m_fds[fd].description()->can_write())
return true;
}
return false;
}
Thread::WaitBlocker::WaitBlocker(int wait_options, ProcessID& waitee_pid)
: m_wait_options(wait_options)
, m_waitee_pid(waitee_pid)
{
}
bool Thread::WaitBlocker::should_unblock(Thread& thread)
{
bool should_unblock = m_wait_options & WNOHANG;
if (m_waitee_pid != -1) {
auto peer = Process::from_pid(m_waitee_pid);
if (!peer)
return true;
}
thread.process().for_each_child([&](Process& child) {
if (m_waitee_pid != -1 && m_waitee_pid != child.pid())
return IterationDecision::Continue;
bool child_exited = child.is_dead();
bool child_stopped = false;
if (child.thread_count()) {
child.for_each_thread([&](auto& child_thread) {
if (child_thread.state() == Thread::State::Stopped && !child_thread.has_pending_signal(SIGCONT)) {
child_stopped = true;
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
}
bool fits_the_spec = ((m_wait_options & WEXITED) && child_exited)
|| ((m_wait_options & WSTOPPED) && child_stopped);
if (!fits_the_spec)
return IterationDecision::Continue;
m_waitee_pid = child.pid();
should_unblock = true;
return IterationDecision::Break;
});
return should_unblock;
}
Thread::SemiPermanentBlocker::SemiPermanentBlocker(Reason reason)
: m_reason(reason)
{
}
bool Thread::SemiPermanentBlocker::should_unblock(Thread&)
{
// someone else has to unblock us
return false;
}
// Called by the scheduler on threads that are blocked for some reason.
// Make a decision as to whether to unblock them or not.
void Thread::consider_unblock(time_t now_sec, long now_usec)
{
ScopedSpinLock lock(m_lock);
switch (state()) {
case Thread::Invalid:
case Thread::Runnable:
case Thread::Running:
case Thread::Dead:
case Thread::Stopped:
case Thread::Queued:
case Thread::Dying:
/* don't know, don't care */
return;
case Thread::Blocked: {
ASSERT(m_blocker != nullptr);
timespec now;
now.tv_sec = now_sec,
now.tv_nsec = now_usec * 1000ull;
bool timed_out = m_blocker_timeout && now >= *m_blocker_timeout;
if (timed_out || m_blocker->should_unblock(*this))
unblock();
return;
}
}
}
void Scheduler::start()
{
ASSERT_INTERRUPTS_DISABLED();
// We need to acquire our scheduler lock, which will be released
// by the idle thread once control transferred there
g_scheduler_lock.lock();
auto& processor = Processor::current();
processor.set_scheduler_data(*new SchedulerPerProcessorData());
ASSERT(processor.is_initialized());
auto& idle_thread = *processor.idle_thread();
ASSERT(processor.current_thread() == &idle_thread);
ASSERT(processor.idle_thread() == &idle_thread);
idle_thread.set_ticks_left(time_slice_for(idle_thread));
idle_thread.did_schedule();
idle_thread.set_initialized(true);
processor.init_context(idle_thread, false);
idle_thread.set_state(Thread::Running);
ASSERT(idle_thread.affinity() == (1u << processor.id()));
processor.initialize_context_switching(idle_thread);
ASSERT_NOT_REACHED();
}
bool Scheduler::pick_next()
{
ASSERT_INTERRUPTS_DISABLED();
auto current_thread = Thread::current();
auto now = time_since_boot();
auto now_sec = now.tv_sec;
auto now_usec = now.tv_usec;
// Set the m_in_scheduler flag before acquiring the spinlock. This
// prevents a recursive call into Scheduler::invoke_async upon
// leaving the scheduler lock.
ScopedCritical critical;
auto& scheduler_data = Processor::current().get_scheduler_data();
scheduler_data.m_in_scheduler = true;
ScopeGuard guard(
[]() {
// We may be on a different processor after we got switched
// back to this thread!
auto& scheduler_data = Processor::current().get_scheduler_data();
ASSERT(scheduler_data.m_in_scheduler);
scheduler_data.m_in_scheduler = false;
});
ScopedSpinLock lock(g_scheduler_lock);
if (current_thread->should_die() && current_thread->state() == Thread::Running) {
// Rather than immediately killing threads, yanking the kernel stack
// away from them (which can lead to e.g. reference leaks), we always
// allow Thread::wait_on to return. This allows the kernel stack to
// clean up and eventually we'll get here shortly before transitioning
// back to user mode (from Processor::exit_trap). At this point we
// no longer want to schedule this thread. We can't wait until
// Scheduler::enter_current because we don't want to allow it to
// transition back to user mode.
#ifdef SCHEDULER_DEBUG
dbg() << "Scheduler[" << Processor::current().id() << "]: Thread " << *current_thread << " is dying";
#endif
current_thread->set_state(Thread::Dying);
}
// Check and unblock threads whose wait conditions have been met.
Scheduler::for_each_nonrunnable([&](Thread& thread) {
thread.consider_unblock(now_sec, now_usec);
return IterationDecision::Continue;
});
Process::for_each([&](Process& process) {
if (process.is_dead()) {
if (current_thread->process().pid() != process.pid() && (!process.ppid() || !Process::from_pid(process.ppid()))) {
auto name = process.name();
auto pid = process.pid();
auto exit_status = Process::reap(process);
dbg() << "Scheduler[" << Processor::current().id() << "]: Reaped unparented process " << name << "(" << pid.value() << "), exit status: " << exit_status.si_status;
}
return IterationDecision::Continue;
}
if (process.m_alarm_deadline && g_uptime > process.m_alarm_deadline) {
process.m_alarm_deadline = 0;
// FIXME: Should we observe this signal somehow?
(void)process.send_signal(SIGALRM, nullptr);
}
return IterationDecision::Continue;
});
// Dispatch any pending signals.
Thread::for_each_living([&](Thread& thread) -> IterationDecision {
ScopedSpinLock lock(thread.get_lock());
if (!thread.has_unmasked_pending_signals())
return IterationDecision::Continue;
// NOTE: dispatch_one_pending_signal() may unblock the process.
bool was_blocked = thread.is_blocked();
if (thread.dispatch_one_pending_signal() == ShouldUnblockThread::No)
return IterationDecision::Continue;
if (was_blocked) {
#ifdef SCHEDULER_DEBUG
dbg() << "Scheduler[" << Processor::current().id() << "]:Unblock " << thread << " due to signal";
#endif
ASSERT(thread.m_blocker != nullptr);
thread.m_blocker->set_interrupted_by_signal();
thread.unblock();
}
return IterationDecision::Continue;
});
#ifdef SCHEDULER_RUNNABLE_DEBUG
dbg() << "Non-runnables:";
Scheduler::for_each_nonrunnable([](Thread& thread) -> IterationDecision {
if (thread.state() == Thread::Queued)
dbg() << " " << String::format("%-12s", thread.state_string()) << " " << thread << " @ " << String::format("%w", thread.tss().cs) << ":" << String::format("%x", thread.tss().eip) << " Reason: " << (thread.wait_reason() ? thread.wait_reason() : "none");
else if (thread.state() == Thread::Dying)
dbg() << " " << String::format("%-12s", thread.state_string()) << " " << thread << " @ " << String::format("%w", thread.tss().cs) << ":" << String::format("%x", thread.tss().eip) << " Finalizable: " << thread.is_finalizable();
else
dbg() << " " << String::format("%-12s", thread.state_string()) << " " << thread << " @ " << String::format("%w", thread.tss().cs) << ":" << String::format("%x", thread.tss().eip);
return IterationDecision::Continue;
});
dbg() << "Runnables:";
Scheduler::for_each_runnable([](Thread& thread) -> IterationDecision {
dbg() << " " << String::format("%3u", thread.effective_priority()) << "/" << String::format("%2u", thread.priority()) << " " << String::format("%-12s", thread.state_string()) << " " << thread << " @ " << String::format("%w", thread.tss().cs) << ":" << String::format("%x", thread.tss().eip);
return IterationDecision::Continue;
});
#endif
Thread* thread_to_schedule = nullptr;
Vector<Thread*, 128> sorted_runnables;
for_each_runnable([&](auto& thread) {
if ((thread.affinity() & (1u << Processor::current().id())) != 0)
sorted_runnables.append(&thread);
if (&thread == scheduler_data.m_pending_beneficiary) {
thread_to_schedule = &thread;
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
if (thread_to_schedule) {
// The thread we're supposed to donate to still exists
const char* reason = scheduler_data.m_pending_donate_reason;
scheduler_data.m_pending_beneficiary = nullptr;
scheduler_data.m_pending_donate_reason = nullptr;
// We need to leave our first critical section before switching context,
// but since we're still holding the scheduler lock we're still in a critical section
critical.leave();
#ifdef SCHEDULER_DEBUG
dbg() << "Processing pending donate to " << *thread_to_schedule << " reason=" << reason;
#endif
return donate_to_and_switch(thread_to_schedule, reason);
}
// Either we're not donating or the beneficiary disappeared.
// Either way clear any pending information
scheduler_data.m_pending_beneficiary = nullptr;
scheduler_data.m_pending_donate_reason = nullptr;
quick_sort(sorted_runnables, [](auto& a, auto& b) { return a->effective_priority() >= b->effective_priority(); });
for (auto* thread : sorted_runnables) {
if (thread->process().exec_tid() && thread->process().exec_tid() != thread->tid())
continue;
ASSERT(thread->state() == Thread::Runnable || thread->state() == Thread::Running);
if (!thread_to_schedule) {
thread->m_extra_priority = 0;
thread_to_schedule = thread;
} else {
thread->m_extra_priority++;
}
}
if (!thread_to_schedule)
thread_to_schedule = Processor::current().idle_thread();
#ifdef SCHEDULER_DEBUG
dbg() << "Scheduler[" << Processor::current().id() << "]: Switch to " << *thread_to_schedule << " @ " << String::format("%04x:%08x", thread_to_schedule->tss().cs, thread_to_schedule->tss().eip);
#endif
// We need to leave our first critical section before switching context,
// but since we're still holding the scheduler lock we're still in a critical section
critical.leave();
return context_switch(thread_to_schedule);
}
bool Scheduler::yield()
{
InterruptDisabler disabler;
auto& proc = Processor::current();
auto& scheduler_data = proc.get_scheduler_data();
// Clear any pending beneficiary
scheduler_data.m_pending_beneficiary = nullptr;
scheduler_data.m_pending_donate_reason = nullptr;
auto current_thread = Thread::current();
#ifdef SCHEDULER_DEBUG
dbg() << "Scheduler[" << proc.id() << "]: yielding thread " << *current_thread << " in_irq: " << proc.in_irq();
#endif
ASSERT(current_thread != nullptr);
if (proc.in_irq() || proc.in_critical()) {
// If we're handling an IRQ we can't switch context, or we're in
// a critical section where we don't want to switch contexts, then
// delay until exiting the trap or critical section
proc.invoke_scheduler_async();
return false;
}
if (!Scheduler::pick_next())
return false;
#ifdef SCHEDULER_DEBUG
dbg() << "Scheduler[" << Processor::current().id() << "]: yield returns to thread " << *current_thread << " in_irq: " << Processor::current().in_irq();
#endif
return true;
}
bool Scheduler::donate_to_and_switch(Thread* beneficiary, const char* reason)
{
ASSERT(g_scheduler_lock.own_lock());
auto& proc = Processor::current();
ASSERT(proc.in_critical() == 1);
(void)reason;
unsigned ticks_left = Thread::current()->ticks_left();
if (!beneficiary || beneficiary->state() != Thread::Runnable || ticks_left <= 1)
return Scheduler::yield();
unsigned ticks_to_donate = min(ticks_left - 1, time_slice_for(*beneficiary));
#ifdef SCHEDULER_DEBUG
dbg() << "Scheduler[" << proc.id() << "]: Donating " << ticks_to_donate << " ticks to " << *beneficiary << ", reason=" << reason;
#endif
beneficiary->set_ticks_left(ticks_to_donate);
return Scheduler::context_switch(beneficiary);
}
bool Scheduler::donate_to(Thread* beneficiary, const char* reason)
{
ASSERT(beneficiary);
if (beneficiary == Thread::current())
return Scheduler::yield();
// Set the m_in_scheduler flag before acquiring the spinlock. This
// prevents a recursive call into Scheduler::invoke_async upon
// leaving the scheduler lock.
ScopedCritical critical;
auto& proc = Processor::current();
auto& scheduler_data = proc.get_scheduler_data();
scheduler_data.m_in_scheduler = true;
ScopeGuard guard(
[]() {
// We may be on a different processor after we got switched
// back to this thread!
auto& scheduler_data = Processor::current().get_scheduler_data();
ASSERT(scheduler_data.m_in_scheduler);
scheduler_data.m_in_scheduler = false;
});
ASSERT(!proc.in_irq());
if (proc.in_critical() > 1) {
scheduler_data.m_pending_beneficiary = beneficiary; // Save the beneficiary
scheduler_data.m_pending_donate_reason = reason;
proc.invoke_scheduler_async();
return false;
}
ScopedSpinLock lock(g_scheduler_lock);
// "Leave" the critical section before switching context. Since we
// still hold the scheduler lock, we're not actually leaving it.
// Processor::switch_context expects Processor::in_critical() to be 1
critical.leave();
donate_to_and_switch(beneficiary, reason);
return false;
}
bool Scheduler::context_switch(Thread* thread)
{
thread->set_ticks_left(time_slice_for(*thread));
thread->did_schedule();
auto from_thread = Thread::current();
if (from_thread == thread)
return false;
if (from_thread) {
// If the last process hasn't blocked (still marked as running),
// mark it as runnable for the next round.
if (from_thread->state() == Thread::Running)
from_thread->set_state(Thread::Runnable);
#ifdef LOG_EVERY_CONTEXT_SWITCH
dbg() << "Scheduler[" << Processor::current().id() << "]: " << *from_thread << " -> " << *thread << " [" << thread->priority() << "] " << String::format("%w", thread->tss().cs) << ":" << String::format("%x", thread->tss().eip);
#endif
}
auto& proc = Processor::current();
if (!thread->is_initialized()) {
proc.init_context(*thread, false);
thread->set_initialized(true);
}
thread->set_state(Thread::Running);
// Mark it as active because we are using this thread. This is similar
// to comparing it with Processor::current_thread, but when there are
// multiple processors there's no easy way to check whether the thread
// is actually still needed. This prevents accidental finalization when
// a thread is no longer in Running state, but running on another core.
thread->set_active(true);
proc.switch_context(from_thread, thread);
// NOTE: from_thread at this point reflects the thread we were
// switched from, and thread reflects Thread::current()
enter_current(*from_thread);
ASSERT(thread == Thread::current());
return true;
}
void Scheduler::enter_current(Thread& prev_thread)
{
ASSERT(g_scheduler_lock.is_locked());
prev_thread.set_active(false);
if (prev_thread.state() == Thread::Dying) {
// If the thread we switched from is marked as dying, then notify
// the finalizer. Note that as soon as we leave the scheduler lock
// the finalizer may free from_thread!
notify_finalizer();
}
}
void Scheduler::leave_on_first_switch(u32 flags)
{
// This is called when a thread is swiched into for the first time.
// At this point, enter_current has already be called, but because
// Scheduler::context_switch is not in the call stack we need to
// clean up and release locks manually here
g_scheduler_lock.unlock(flags);
auto& scheduler_data = Processor::current().get_scheduler_data();
ASSERT(scheduler_data.m_in_scheduler);
scheduler_data.m_in_scheduler = false;
}
void Scheduler::prepare_after_exec()
{
// This is called after exec() when doing a context "switch" into
// the new process. This is called from Processor::assume_context
ASSERT(g_scheduler_lock.own_lock());
auto& scheduler_data = Processor::current().get_scheduler_data();
ASSERT(!scheduler_data.m_in_scheduler);
scheduler_data.m_in_scheduler = true;
}
void Scheduler::prepare_for_idle_loop()
{
// This is called when the CPU finished setting up the idle loop
// and is about to run it. We need to acquire he scheduler lock
ASSERT(!g_scheduler_lock.own_lock());
g_scheduler_lock.lock();
auto& scheduler_data = Processor::current().get_scheduler_data();
ASSERT(!scheduler_data.m_in_scheduler);
scheduler_data.m_in_scheduler = true;
}
Process* Scheduler::colonel()
{
ASSERT(s_colonel_process);
return s_colonel_process;
}
void Scheduler::initialize()
{
ASSERT(&Processor::current() != nullptr); // sanity check
Thread* idle_thread = nullptr;
g_scheduler_data = new SchedulerData;
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).leak_ref();
ASSERT(s_colonel_process);
ASSERT(idle_thread);
idle_thread->set_priority(THREAD_PRIORITY_MIN);
idle_thread->set_name(StringView("idle thread #0"));
set_idle_thread(idle_thread);
}
void Scheduler::set_idle_thread(Thread* idle_thread)
{
Processor::current().set_idle_thread(*idle_thread);
Processor::current().set_current_thread(*idle_thread);
}
Thread* Scheduler::create_ap_idle_thread(u32 cpu)
{
ASSERT(cpu != 0);
// This function is called on the bsp, but creates an idle thread for another AP
ASSERT(Processor::current().id() == 0);
ASSERT(s_colonel_process);
Thread* idle_thread = s_colonel_process->create_kernel_thread(idle_loop, THREAD_PRIORITY_MIN, String::format("idle thread #%u", cpu), 1 << cpu, false);
ASSERT(idle_thread);
return idle_thread;
}
void Scheduler::timer_tick(const RegisterState& regs)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(Processor::current().in_irq());
if (Processor::current().id() > 0)
return;
auto current_thread = Processor::current().current_thread();
if (!current_thread)
return;
++g_uptime;
g_timeofday = TimeManagement::now_as_timeval();
if (current_thread->process().is_profiling()) {
SmapDisabler disabler;
auto backtrace = current_thread->raw_backtrace(regs.ebp, regs.eip);
auto& sample = Profiling::next_sample_slot();
sample.pid = current_thread->process().pid();
sample.tid = current_thread->tid();
sample.timestamp = g_uptime;
for (size_t i = 0; i < min(backtrace.size(), Profiling::max_stack_frame_count); ++i) {
sample.frames[i] = backtrace[i];
}
}
TimerQueue::the().fire();
if (current_thread->tick())
return;
ASSERT_INTERRUPTS_DISABLED();
ASSERT(Processor::current().in_irq());
Processor::current().invoke_scheduler_async();
}
void Scheduler::invoke_async()
{
ASSERT_INTERRUPTS_DISABLED();
auto& proc = Processor::current();
ASSERT(!proc.in_irq());
// Since this function is called when leaving critical sections (such
// as a SpinLock), we need to check if we're not already doing this
// to prevent recursion
if (!proc.get_scheduler_data().m_in_scheduler)
pick_next();
}
void Scheduler::notify_finalizer()
{
if (g_finalizer_has_work.exchange(true, AK::MemoryOrder::memory_order_acq_rel) == false)
g_finalizer_wait_queue->wake_all();
}
void Scheduler::idle_loop()
{
dbg() << "Scheduler[" << Processor::current().id() << "]: idle loop running";
ASSERT(are_interrupts_enabled());
for (;;) {
asm("hlt");
if (Processor::current().id() == 0)
yield();
}
}
}
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