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Allow condition variables to be used in interrupt code. 

Adjust the condition variable sleep loop to work correctly when code
reached by its internal CHECK_FOR_INTERRUPTS() call interacts with
another condition variable.

There are no such cases currently, but a proposed patch would do this.

Discussion: https://postgr.es/m/CA+hUKGLdemy2gBm80kz20GTe6hNVwoErE8KwcJk6-U56oStjtg@mail.gmail.com
This commit is contained in:
Thomas Munro 2021-03-01 16:28:12 +13:00
parent 814f1d8bc3
commit f5a5773a9d
1 changed files with 9 additions and 2 deletions
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11
src/backend/storage/lmgr/condition_variable.c
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@ -165,8 +165,6 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout,
/* Reset latch before examining the state of the wait list. */
ResetLatch(MyLatch);
CHECK_FOR_INTERRUPTS();
/*
* If this process has been taken out of the wait list, then we know
* that it has been signaled by ConditionVariableSignal (or
@ -190,6 +188,15 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout,
}
SpinLockRelease(&cv->mutex);
/*
* Check for interrupts, and return spuriously if that caused the
* current sleep target to change (meaning that interrupt handler code
* waited for a different condition variable).
*/
CHECK_FOR_INTERRUPTS();
if (cv != cv_sleep_target)
done = true;
/* We were signaled, so return */
if (done)
return false;