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kernel/condition_variable: Check thread->state before unblock.

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See inline comments. Should help with #17444.
This commit is contained in:
Augustin Cavalier 2021-12-07 13:30:36 -05:00
parent b3780b5658
commit acdd232ad5
1 changed files with 5 additions and 2 deletions
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7
src/system/kernel/condition_variable.cpp
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@ -401,7 +401,8 @@ ConditionVariable::_NotifyLocked(bool all, status_t result)
const status_t waitStatus = atomic_get_and_set(&entry->fWaitStatus, result);
// Prevent the thread from changing status after we unset its fVariable,
// as otherwise it could re-block itself before we call thread_unblock.
// as otherwise it could become unblocked (or may already be so) and then
// re-block itself on something else before we call thread_unblock.
SpinLocker threadLocker(thread->scheduler_lock);
// No matter what the thread is doing, as we were the ones to clear its
@ -412,7 +413,9 @@ ConditionVariable::_NotifyLocked(bool all, status_t result)
// Do this after unsetting fVariable, as in case the entry wakes up
// and tries to remove itself, it need not not have to wait for us.
if (waitStatus == STATUS_WAITING)
// (We check thread->state here as it cannot change while we hold
// the scheduler lock, unlike thread_is_blocked, which can!)
if (waitStatus == STATUS_WAITING && thread->state == B_THREAD_WAITING)
thread_unblock_locked(thread, result);
}