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bind/backport-0044-Use-a-reference-counter-for-zt.patch
jiangheng ad37c37958 backport some patches from community 
(cherry picked from commit a9fd9ece9b9436b6103d084920c6897ef1adbae6)
2022-09-03 21:36:21 +08:00

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From 7db778854e35f2dcea2a08207110dfed9366e8a5 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Mon, 31 Aug 2020 19:28:38 +1000
Subject: [PATCH] Use a reference counter for zt
WARNING: ThreadSanitizer: data race
Write of size 8 at 0x000000000001 by thread T1 (mutexes: write M1):
#0 memset <null>
#1 mem_put lib/isc/mem.c:819
#2 isc___mem_free lib/isc/mem.c:1662
#3 isc__mem_free lib/isc/mem.c:3078
#4 isc___mem_putanddetach lib/isc/mem.c:1221
#5 isc__mem_putanddetach lib/isc/mem.c:3033
#6 zt_destroy lib/dns/zt.c:214
#7 doneloading lib/dns/zt.c:591
#8 zone_asyncload lib/dns/zone.c:2243
#9 dispatch lib/isc/task.c:1157
#10 run lib/isc/task.c:1331
#11 <null> <null>
Previous atomic read of size 8 at 0x000000000001 by thread T2:
#0 __tsan_atomic64_load <null>
#1 isc_rwlock_unlock lib/isc/rwlock.c:612
#2 doneloading lib/dns/zt.c:585
#3 zone_asyncload lib/dns/zone.c:2243
#4 dispatch lib/isc/task.c:1157
#5 run lib/isc/task.c:1331
#6 <null> <null>
Location is heap block of size 273 at 0x000000000015 allocated by thread T3:
#0 malloc <null>
#1 internal_memalloc lib/isc/mem.c:887
#2 mem_get lib/isc/mem.c:792
#3 mem_allocateunlocked lib/isc/mem.c:1545
#4 isc___mem_allocate lib/isc/mem.c:1566
#5 isc__mem_allocate lib/isc/mem.c:3048
#6 isc___mem_get lib/isc/mem.c:1304
#7 isc__mem_get lib/isc/mem.c:3012
#8 dns_zt_create lib/dns/zt.c:85
#9 dns_view_create lib/dns/view.c:126
#10 create_view server.c:5312
#11 load_configuration server.c:8101
#12 loadconfig server.c:9428
#13 ns_server_reconfigcommand server.c:9763
#14 ns_control_docommand bin/named/control.c:243
#15 control_recvmessage bin/named/controlconf.c:465
#16 dispatch lib/isc/task.c:1157
#17 run lib/isc/task.c:1331
#18 <null> <null>
Conflict: NA
Reference: https://gitlab.isc.org/isc-projects/bind9/-/commit/7db778854e35f2dcea2a08207110dfed9366e8a5
---
lib/dns/zt.c | 63 ++++++++++++++++++++++------------------------------
1 file changed, 26 insertions(+), 37 deletions(-)
diff --git a/lib/dns/zt.c b/lib/dns/zt.c
index 8098b90d1f..14d8bcd6be 100644
--- a/lib/dns/zt.c
+++ b/lib/dns/zt.c
@@ -41,9 +41,10 @@ struct dns_zt {
isc_rwlock_t rwlock;
dns_zt_allloaded_t loaddone;
void * loaddone_arg;
+ isc_refcount_t references;
+
/* Locked by lock. */
- bool flush;
- uint32_t references;
+ bool flush;
unsigned int loads_pending;
dns_rbt_t *table;
};
@@ -97,7 +98,7 @@ dns_zt_create(isc_mem_t *mctx, dns_rdataclass_t rdclass, dns_zt_t **ztp) {
zt->mctx = NULL;
isc_mem_attach(mctx, &zt->mctx);
- zt->references = 1;
+ isc_refcount_init(&zt->references, 1);
zt->flush = false;
zt->rdclass = rdclass;
zt->magic = ZTMAGIC;
@@ -187,13 +188,7 @@ dns_zt_attach(dns_zt_t *zt, dns_zt_t **ztp) {
REQUIRE(VALID_ZT(zt));
REQUIRE(ztp != NULL && *ztp == NULL);
- RWLOCK(&zt->rwlock, isc_rwlocktype_write);
-
- INSIST(zt->references > 0);
- zt->references++;
- INSIST(zt->references != 0);
-
- RWUNLOCK(&zt->rwlock, isc_rwlocktype_write);
+ isc_refcount_increment(&zt->references, NULL);
*ztp = zt;
}
@@ -206,8 +201,10 @@ flush(dns_zone_t *zone, void *uap) {
static void
zt_destroy(dns_zt_t *zt) {
- if (zt->flush)
+ if (zt->flush) {
(void)dns_zt_apply(zt, false, flush, NULL);
+ }
+ isc_refcount_destroy(&zt->references);
dns_rbt_destroy(&zt->table);
isc_rwlock_destroy(&zt->rwlock);
zt->magic = 0;
@@ -216,28 +213,24 @@ zt_destroy(dns_zt_t *zt) {
static void
zt_flushanddetach(dns_zt_t **ztp, bool need_flush) {
- bool destroy = false;
+ unsigned int refs;
dns_zt_t *zt;
REQUIRE(ztp != NULL && VALID_ZT(*ztp));
zt = *ztp;
+ *ztp = NULL;
- RWLOCK(&zt->rwlock, isc_rwlocktype_write);
-
- INSIST(zt->references > 0);
- zt->references--;
- if (zt->references == 0)
- destroy = true;
- if (need_flush)
+ if (need_flush) {
+ RWLOCK(&zt->rwlock, isc_rwlocktype_write);
zt->flush = true;
+ RWUNLOCK(&zt->rwlock, isc_rwlocktype_write);
+ }
- RWUNLOCK(&zt->rwlock, isc_rwlocktype_write);
-
- if (destroy)
+ isc_refcount_decrement(&zt->references, &refs);
+ if (refs == 0) {
zt_destroy(zt);
-
- *ztp = NULL;
+ }
}
void
@@ -301,13 +294,11 @@ dns_zt_asyncload2(dns_zt_t *zt, dns_zt_allloaded_t alldone, void *arg,
*/
zt->loads_pending++;
result = dns_zt_apply2(zt, false, NULL, asyncload, &params);
-
pending = --zt->loads_pending;
if (pending != 0) {
zt->loaddone = alldone;
zt->loaddone_arg = arg;
}
-
RWUNLOCK(&zt->rwlock, isc_rwlocktype_write);
if (pending == 0)
@@ -329,18 +320,18 @@ asyncload(dns_zone_t *zone, void *paramsv) {
dns_zt_t *zt;
REQUIRE(zone != NULL);
- zt = dns_zone_getview(zone)->zonetable;
+ zt = params->zt;
INSIST(VALID_ZT(zt));
- INSIST(zt->references > 0);
- zt->references++;
+ isc_refcount_increment(&zt->references, NULL);
zt->loads_pending++;
result = dns_zone_asyncload2(zone, *params->dl, zt, params->newonly);
if (result != ISC_R_SUCCESS) {
- zt->references--;
+ unsigned int refs;
zt->loads_pending--;
- INSIST(zt->references > 0);
+ isc_refcount_decrement(&zt->references, &refs);
+ INSIST(refs > 0);
}
return (ISC_R_SUCCESS);
}
@@ -560,7 +551,7 @@ dns_zt_apply2(dns_zt_t *zt, bool stop, isc_result_t *sub,
*/
static isc_result_t
doneloading(dns_zt_t *zt, dns_zone_t *zone, isc_task_t *task) {
- bool destroy = false;
+ unsigned int refs;
dns_zt_allloaded_t alldone = NULL;
void *arg = NULL;
@@ -571,10 +562,6 @@ doneloading(dns_zt_t *zt, dns_zone_t *zone, isc_task_t *task) {
RWLOCK(&zt->rwlock, isc_rwlocktype_write);
INSIST(zt->loads_pending != 0);
- INSIST(zt->references != 0);
- zt->references--;
- if (zt->references == 0)
- destroy = true;
zt->loads_pending--;
if (zt->loads_pending == 0) {
alldone = zt->loaddone;
@@ -587,8 +574,10 @@ doneloading(dns_zt_t *zt, dns_zone_t *zone, isc_task_t *task) {
if (alldone != NULL)
alldone(arg);
- if (destroy)
+ isc_refcount_decrement(&zt->references, &refs);
+ if (refs == 0) {
zt_destroy(zt);
+ }
return (ISC_R_SUCCESS);
}
--
2.23.0
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