From: Ondřej Surý <ondrej@isc.org>
Date: Mon, 14 Apr 2025 16:56:54 +0000 (+0200)
Subject: Unify the int32_t vs int_fast32_t when working with atomic types
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ae54bd80764300982045f5611adcfce13262b2f4;p=thirdparty%2Fbind9.git

Unify the int32_t vs int_fast32_t when working with atomic types

There's a mismatch between the atomic and non-atomic types that could
potentialy lead to a rwlock deadlock (after two billion 2^32) writes.
Use int_fast32_t when loading the atomic_int_fast32_t types in the
isc_rwlock unit.

(cherry picked from commit 86673ee67aacf677c96f8272e4a0b9fa65e06310)
---

diff --git a/lib/isc/rwlock.c b/lib/isc/rwlock.c
index aa1156555db..2617e554ad5 100644
--- a/lib/isc/rwlock.c
+++ b/lib/isc/rwlock.c
@@ -307,7 +307,7 @@ isc_rwlock_destroy(isc_rwlock_t *rwl) {
 
 static isc_result_t
 isc__rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
-	int32_t cntflag;
+	int_fast32_t cntflag;
 
 	REQUIRE(VALID_RWLOCK(rwl));
 
@@ -385,7 +385,7 @@ isc__rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
 		 */
 		atomic_store_release(&rwl->write_granted, 0);
 	} else {
-		int32_t prev_writer;
+		int_fast32_t prev_writer;
 
 		/* enter the waiting queue, and wait for our turn */
 		prev_writer = atomic_fetch_add_release(&rwl->write_requests, 1);
@@ -430,9 +430,9 @@ isc__rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
 
 isc_result_t
 isc_rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
-	int32_t cnt = 0;
-	int32_t spins = atomic_load_acquire(&rwl->spins) * 2 + 10;
-	int32_t max_cnt = ISC_MAX(spins, RWLOCK_MAX_ADAPTIVE_COUNT);
+	int_fast32_t cnt = 0;
+	int_fast32_t spins = atomic_load_acquire(&rwl->spins) * 2 + 10;
+	int_fast32_t max_cnt = ISC_MAX(spins, RWLOCK_MAX_ADAPTIVE_COUNT);
 	isc_result_t result = ISC_R_SUCCESS;
 
 	do {
@@ -450,7 +450,7 @@ isc_rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
 
 isc_result_t
 isc_rwlock_trylock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
-	int32_t cntflag;
+	int_fast32_t cntflag;
 
 	REQUIRE(VALID_RWLOCK(rwl));
 
@@ -547,7 +547,7 @@ isc_rwlock_tryupgrade(isc_rwlock_t *rwl) {
 
 void
 isc_rwlock_downgrade(isc_rwlock_t *rwl) {
-	int32_t prev_readers;
+	int_fast32_t prev_readers;
 
 	REQUIRE(VALID_RWLOCK(rwl));
 
@@ -571,7 +571,7 @@ isc_rwlock_downgrade(isc_rwlock_t *rwl) {
 
 isc_result_t
 isc_rwlock_unlock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
-	int32_t prev_cnt;
+	int_fast32_t prev_cnt;
 
 	REQUIRE(VALID_RWLOCK(rwl));