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Kernel: Make sure we can allocate kernel stack before creating thread

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Wrap thread creation in a Thread::try_create() helper that first
allocates a kernel stack region. If that allocation fails, we propagate
an ENOMEM error to the caller.

This avoids the situation where a thread is half-constructed, without a
valid kernel stack, and avoids having to do messy cleanup in that case.
This commit is contained in:
Andreas Kling 2021-02-07 18:13:51 +01:00
parent 5c45b0d32d
commit b466ede1ea
4 changed files with 32 additions and 29 deletions
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25
Kernel/Thread.cpp
View file

@ -53,20 +53,29 @@ void Thread::initialize()
g_tid_map = new HashMap<ThreadID, Thread*>();
}
Thread::Thread(NonnullRefPtr<Process> process)
KResultOr<NonnullRefPtr<Thread>> Thread::try_create(NonnullRefPtr<Process> process)
{
auto kernel_stack_region = MM.allocate_kernel_region(default_kernel_stack_size, {}, Region::Access::Read | Region::Access::Write, false, AllocationStrategy::AllocateNow);
if (!kernel_stack_region)
return ENOMEM;
return adopt(*new Thread(move(process), kernel_stack_region.release_nonnull()));
}
Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Region> kernel_stack_region)
: m_process(move(process))
, m_kernel_stack_region(move(kernel_stack_region))
, m_name(m_process->name())
{
bool is_first_thread = m_process->add_thread(*this);
ArmedScopeGuard guard([&]() {
drop_thread_count(is_first_thread);
});
if (is_first_thread) {
// First thread gets TID == PID
m_tid = m_process->pid().value();
} else {
m_tid = Process::allocate_pid().value();
}
m_kernel_stack_region->set_name(String::formatted("Kernel stack (thread {})", m_tid.value()));
{
ScopedSpinLock lock(g_tid_map_lock);
auto result = g_tid_map->set(m_tid, this);
@ -126,7 +135,6 @@ Thread::Thread(NonnullRefPtr<Process> process)
// The finalizer is responsible for dropping this reference once this
// thread is ready to be cleaned up.
ref();
guard.disarm();
}
Thread::~Thread()
@ -881,11 +889,10 @@ RegisterState& Thread::get_register_dump_from_stack()
RefPtr<Thread> Thread::clone(Process& process)
{
auto clone = adopt(*new Thread(process));
if (!clone->was_created()) {
// We failed to clone this thread
auto thread_or_error = Thread::try_create(process);
if (thread_or_error.is_error())
return {};
}
auto& clone = thread_or_error.value();
memcpy(clone->m_signal_action_data, m_signal_action_data, sizeof(m_signal_action_data));
clone->m_signal_mask = m_signal_mask;
memcpy(clone->m_fpu_state, m_fpu_state, sizeof(FPUState));