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Kernel: Fix some problems with Thread::wait_on and Lock

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This changes the Thread::wait_on function to not enable interrupts
upon leaving, which caused some problems with page fault handlers
and in other situations. It may now be called from critical
sections, with interrupts enabled or disabled, and returns to the
same state.

This also requires some fixes to Lock. To aid debugging, a new
define LOCK_DEBUG is added that enables checking for Lock leaks
upon finalization of a Thread.
This commit is contained in:
Tom 2020-11-30 19:04:36 -07:00 • committed by Andreas Kling
parent 9e32d79e02
commit 78f1b5e359
10 changed files with 178 additions and 83 deletions
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24
Kernel/Thread.cpp
View file

@ -316,7 +316,16 @@ void Thread::finalize()
ASSERT(Thread::current() == g_finalizer);
ASSERT(Thread::current() != this);
#ifdef LOCK_DEBUG
ASSERT(!m_lock.own_lock());
if (lock_count() > 0) {
dbg() << "Thread " << *this << " leaking " << lock_count() << " Locks!";
ScopedSpinLock list_lock(m_holding_locks_lock);
for (auto& info : m_holding_locks_list)
dbg() << " - " << info.lock->name() << " @ " << info.lock << " locked at " << info.file << ":" << info.line << " count: " << info.count;
ASSERT_NOT_REACHED();
}
#endif
{
ScopedSpinLock lock(g_scheduler_lock);
@ -1080,10 +1089,9 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, const
}
});
if (!timer) {
if (lock)
*lock = false;
// We timed out already, don't block
// The API contract guarantees we return with interrupts enabled,
// regardless of how we got called
critical.set_interrupt_flag_on_destruction(true);
return BlockResult::InterruptedByTimeout;
}
}
@ -1094,16 +1102,13 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, const
// The WaitQueue was already requested to wake someone when
// nobody was waiting. So return right away as we shouldn't
// be waiting
// The API contract guarantees we return with interrupts enabled,
// regardless of how we got called
critical.set_interrupt_flag_on_destruction(true);
// NOTE: Do not set lock to false in this case!
return BlockResult::NotBlocked;
}
did_unlock = unlock_process_if_locked();
if (lock)
*lock = false;
did_unlock = unlock_process_if_locked();
set_state(State::Queued);
m_wait_reason = reason;
@ -1158,9 +1163,6 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, const
TimerQueue::the().cancel_timer(timer.release_nonnull());
}
// The API contract guarantees we return with interrupts enabled,
// regardless of how we got called
sti();
return result;
}