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Kernel: Stop swallowing thread unblocks while process is stopped

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This easily led to kernel deadlocks if the stopped thread held an
important global mutex (like the disk cache lock) while blocking.
Resolve this by ensuring stopped threads have a chance to return to the
userland boundary before actually stopping.
This commit is contained in:
Idan Horowitz 2024-02-09 21:13:41 +02:00 • committed by Andreas Kling
parent 458e990b7b
commit e38ccebfc8
4 changed files with 24 additions and 23 deletions
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11
Kernel/Tasks/Scheduler.cpp
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@ -268,9 +268,14 @@ void Scheduler::context_switch(Thread* thread)
return;
// If the last process hasn't blocked (still marked as running),
// mark it as runnable for the next round.
if (from_thread->state() == Thread::State::Running)
from_thread->set_state(Thread::State::Runnable);
// mark it as runnable for the next round, unless it's supposed
// to be stopped, in which case just mark it as such.
if (from_thread->state() == Thread::State::Running) {
if (from_thread->should_be_stopped())
from_thread->set_state(Thread::State::Stopped);
else
from_thread->set_state(Thread::State::Runnable);
}
#ifdef LOG_EVERY_CONTEXT_SWITCH
auto const msg = "Scheduler[{}]: {} -> {} [prio={}] {:p}";