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Kernel: Fix Thread::relock_process leaving critical section

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We don't want to explicitly enable interrupts when leaving the
critical section to trigger a context switch.
This commit is contained in:
Tom 2021-01-23 22:41:44 -07:00 committed by Andreas Kling
parent ccaeb47401
commit e9e76b8074
Notes: sideshowbarker 2024-07-18 22:48:26 +09:00 
Author: https://github.com/tomuta
Commit: https://github.com/SerenityOS/serenity/commit/e9e76b80749
Pull-request: https://github.com/SerenityOS/serenity/pull/5073
2 changed files with 11 additions and 9 deletions
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9
Kernel/Scheduler.cpp
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@ -583,16 +583,19 @@ void Scheduler::invoke_async()
void Scheduler::yield_from_critical()
{
auto& proc = Processor::current();
ASSERT(proc.in_critical());
auto before_critical = proc.in_critical();
ASSERT(before_critical);
ASSERT(!proc.in_irq());
yield(); // Flag a context switch
u32 prev_flags;
u32 prev_crit = Processor::current().clear_critical(prev_flags, false);
u32 prev_crit = proc.clear_critical(prev_flags, false);
// Note, we may now be on a different CPU!
Processor::current().restore_critical(prev_crit, prev_flags);
auto& new_proc = Processor::current();
new_proc.restore_critical(prev_crit, prev_flags);
ASSERT(before_critical == new_proc.in_critical());
}
void Scheduler::notify_finalizer()

11
Kernel/Thread.cpp
View file

@ -305,17 +305,16 @@ void Thread::relock_process(LockMode previous_locked, u32 lock_count_to_restore)
// flagged by calling Scheduler::donate_to or Scheduler::yield
// above. We have to do it this way because we intentionally
// leave the critical section here to be able to switch contexts.
u32 prev_flags;
u32 prev_crit = Processor::current().clear_critical(prev_flags, true);
auto critical_before = Processor::current().in_critical();
ASSERT(critical_before);
// CONTEXT SWITCH HAPPENS HERE!
// NOTE: We may be on a different CPU now!
Processor::current().restore_critical(prev_crit, prev_flags);
Scheduler::yield_from_critical();
ASSERT(Processor::current().in_critical() == critical_before);
if (previous_locked != LockMode::Unlocked) {
// We've unblocked, relock the process if needed and carry on.
RESTORE_LOCK(process().big_lock(), previous_locked, lock_count_to_restore);
ASSERT(Processor::current().in_critical() == critical_before);
}
}