[CF 5736] v1 - Fix a race condition in ConditionVariableTimedSleep()

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Patch(es): https://www.postgresql.org/message-id/aBhuTqNhMN3prcqe@ip-10-97-1-34.eu-west-3.compute.internal
Author(s): Bertrand Drouvot

Author: Commitfest Bot

src/backend/storage/lmgr/condition_variable.c

@@ -184,6 +184,8 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout,
 		if (!proclist_contains(&cv->wakeup, MyProcNumber, cvWaitLink))
 		{
 			done = true;
+			if (cv_sleep_target == NULL)
+				cv_sleep_target = cv;
 			proclist_push_tail(&cv->wakeup, MyProcNumber, cvWaitLink);
 		}
 		SpinLockRelease(&cv->mutex);