From 4c2eda67f55a8a263820d12aaeaa7e1dfe7406ee Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <akorotkov@postgresql.org>
Date: Fri, 15 Mar 2024 14:31:25 +0200
Subject: Fix race condition in transaction timeout TAP tests

The interruption handler within the injection point can get stuck in an
infinite loop while handling transaction timeout. To avoid this situation
we reset the timeout flag before invoking the injection point.

Author: Alexander Korotkov
Reviewed-by: Andrey Borodin
Discussion: https://postgr.es/m/ZfPchPC6oNN71X2J%40paquier.xyz
---
 src/backend/tcop/postgres.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

(limited to 'src/backend/tcop/postgres.c')

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 7ac623019bc..fd4199a0983 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3409,8 +3409,10 @@ ProcessInterrupts(void)
 		/*
 		 * If the GUC has been reset to zero, ignore the signal.  This is
 		 * important because the GUC update itself won't disable any pending
-		 * interrupt.
+		 * interrupt.  We need to unset the flag before the injection point,
+		 * otherwise we could loop in interrupts checking.
 		 */
+		IdleInTransactionSessionTimeoutPending = false;
 		if (IdleInTransactionSessionTimeout > 0)
 		{
 			INJECTION_POINT("idle-in-transaction-session-timeout");
@@ -3418,13 +3420,12 @@ ProcessInterrupts(void)
 					(errcode(ERRCODE_IDLE_IN_TRANSACTION_SESSION_TIMEOUT),
 					 errmsg("terminating connection due to idle-in-transaction timeout")));
 		}
-		else
-			IdleInTransactionSessionTimeoutPending = false;
 	}
 
 	if (TransactionTimeoutPending)
 	{
 		/* As above, ignore the signal if the GUC has been reset to zero. */
+		TransactionTimeoutPending = false;
 		if (TransactionTimeout > 0)
 		{
 			INJECTION_POINT("transaction-timeout");
@@ -3432,13 +3433,12 @@ ProcessInterrupts(void)
 					(errcode(ERRCODE_TRANSACTION_TIMEOUT),
 					 errmsg("terminating connection due to transaction timeout")));
 		}
-		else
-			TransactionTimeoutPending = false;
 	}
 
 	if (IdleSessionTimeoutPending)
 	{
 		/* As above, ignore the signal if the GUC has been reset to zero. */
+		IdleSessionTimeoutPending = false;
 		if (IdleSessionTimeout > 0)
 		{
 			INJECTION_POINT("idle-session-timeout");
@@ -3446,8 +3446,6 @@ ProcessInterrupts(void)
 					(errcode(ERRCODE_IDLE_SESSION_TIMEOUT),
 					 errmsg("terminating connection due to idle-session timeout")));
 		}
-		else
-			IdleSessionTimeoutPending = false;
 	}
 
 	/*
-- 
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