Lock access to acache stats when not using atomics

    WARNING: ThreadSanitizer: data race
    Write of size 4 at 0x000000000001 by thread T1 (mutexes: write M1):
    #0 dns_acache_getentry lib/dns/acache.c:1549:2
    #1 rdataset_getadditional lib/dns/rbtdb.c:9912:11
    #2 dns_rdataset_getadditional lib/dns/rdataset.c:711:11
    #3 query_addadditional2 bin/named/query.c:1991:11
    #4 additionaldata_ns lib/dns/./rdata/generic/ns_2.c:198:10
    #5 dns_rdata_additionaldata lib/dns/rdata.c:1246:2
    #6 dns_rdataset_additionaldata lib/dns/rdataset.c:629:12
    #7 query_addrdataset bin/named/query.c:2435:8
    #8 query_addrrset bin/named/query.c:2826:2
    #9 query_addbestns bin/named/query.c:3525:2
    #10 query_find bin/named/query.c:9204:4
    #11 query_resume bin/named/query.c:4188:12
    #12 dispatch lib/isc/task.c:1157:7
    #13 run lib/isc/task.c:1331:2

    Previous write of size 4 at 0x000000000001 by thread T2 (mutexes: write M2):
    #0 dns_acache_countquerymiss lib/dns/acache.c:1201:2
    #1 rdataset_getadditional lib/dns/rbtdb.c:9896:4
    #2 dns_rdataset_getadditional lib/dns/rdataset.c:711:11
    #3 query_addadditional2 bin/named/query.c:1991:11
    #4 additionaldata_ns lib/dns/./rdata/generic/ns_2.c:198:10
    #5 dns_rdata_additionaldata lib/dns/rdata.c:1246:2
    #6 dns_rdataset_additionaldata lib/dns/rdataset.c:629:12
    #7 query_addrdataset bin/named/query.c:2435:8
    #8 query_addrrset bin/named/query.c:2826:2
    #9 query_find bin/named/query.c:9176:4
    #10 query_resume bin/named/query.c:4188:12
    #11 dispatch lib/isc/task.c:1157:7

diff --git a/lib/dns/acache.c b/lib/dns/acache.c
index 99646d59b2434e1dd5de51de21179cab21f211ff..cd87b84a5199ba62e7e36dda5bc63ee3354b1eba 100644 (file)
--- a/lib/dns/acache.c
+++ b/lib/dns/acache.c
@@ -178,6 +178,8 @@ struct dns_acachestats {
        _Atomic(unsigned int)           hits;
        _Atomic(unsigned int)           queries;
        _Atomic(unsigned int)           misses;
+#define ACACHE_STATSLOCK(x) (void)0
+#define ACACHE_STATSUNLOCK(x) (void)0
 #define ACACHE_INC(x)  atomic_fetch_add(&(x), 1)
 #define ACACHE_LOAD(x)  atomic_load(&(x))
 #else
@@ -185,9 +187,15 @@ struct dns_acachestats {
        unsigned int                    queries;
        unsigned int                    misses;
 #if defined(ISC_PLATFORM_HAVEXADD)
+#define ACACHE_STATSLOCK(x) (void)0
+#define ACACHE_STATSUNLOCK(x) (void)0
 #define ACACHE_INC(x) isc_atomic_xadd((int32_t*)&(x), 1)
 #define ACACHE_LOAD(x) isc_atomic_xadd((int32_t*)&(x), 0)
 #else
+       isc_mutex_t                     lock;
+#define ISC_HAVE_STATSLOCK
+#define ACACHE_STATSLOCK(l)    LOCK(l)
+#define ACACHE_STATSUNLOCK(l)  UNLOCK(l)
 #define ACACHE_INC(x) ((x)++)
 #define ACACHE_LOAD(x) (x)
 #endif
@@ -487,6 +495,10 @@ destroy(dns_acache_t *acache) {
 
        DESTROYLOCK(&acache->cleaner.lock);
 
+#ifdef ISC_HAVE_STATSLOCK
+       DESTROYLOCK(&acache->stats.lock);
+#endif
+
        DESTROYLOCK(&acache->lock);
        acache->magic = 0;
 
@@ -724,6 +736,7 @@ end_cleaning(acache_cleaner_t *cleaner, isc_event_t *event) {
        acache->stats.cleaned += cleaner->ncleaned;
        acache->stats.cleaner_runs++;
 
+       ACACHE_STATSLOCK(&acache->stats.lock);
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_ACACHE,
                      ISC_LOG_NOTICE,
                      "acache %p stats: hits=%d misses=%d queries=%d "
@@ -739,6 +752,7 @@ end_cleaning(acache_cleaner_t *cleaner, isc_event_t *event) {
                      acache->stats.overmem, acache->stats.overmem_nocreates,
                      acache->stats.nomem);
        reset_stats(acache);
+       ACACHE_STATSUNLOCK(&acache->stats.lock);
 
        isc_stdtime_get(&cleaner->last_cleanup_time);
 
@@ -1105,6 +1119,17 @@ dns_acache_create(dns_acache_t **acachep, isc_mem_t *mctx,
                return (result);
        }
 
+#ifdef ISC_HAVE_STATSLOCK
+       result = isc_mutex_init(&acache->stats.lock);
+       if (result != ISC_R_SUCCESS) {
+               DESTROYLOCK(&acache->lock);
+               isc_refcount_decrement(&acache->refs, NULL);
+               isc_refcount_destroy(&acache->refs);
+               isc_mem_put(mctx, acache, sizeof(*acache));
+               return (result);
+       }
+#endif
+
        acache->mctx = NULL;
        isc_mem_attach(mctx, &acache->mctx);
        ISC_LIST_INIT(acache->entries);
@@ -1167,6 +1192,9 @@ dns_acache_create(dns_acache_t **acachep, isc_mem_t *mctx,
  cleanup:
        if (acache->task != NULL)
                isc_task_detach(&acache->task);
+#ifdef ISC_HAVE_STATSLOCK
+       DESTROYLOCK(&acache->stats.lock);
+#endif
        DESTROYLOCK(&acache->lock);
        isc_refcount_decrement(&acache->refs, NULL);
        isc_refcount_destroy(&acache->refs);
@@ -1197,8 +1225,10 @@ dns_acache_attach(dns_acache_t *source, dns_acache_t **targetp) {
 
 void
 dns_acache_countquerymiss(dns_acache_t *acache) {
+       ACACHE_STATSLOCK(&acache->stats.lock);
        ACACHE_INC(acache->stats.misses);
        ACACHE_INC(acache->stats.queries);
+       ACACHE_STATSUNLOCK(&acache->stats.lock);
 }
 
 void
@@ -1545,8 +1575,10 @@ dns_acache_getentry(dns_acacheentry_t *entry, dns_zone_t **zonep,
                }
        }
 
+       ACACHE_STATSLOCK(&entry->acache->stats.lock);
        ACACHE_INC(entry->acache->stats.hits);
        ACACHE_INC(entry->acache->stats.queries);
+       ACACHE_STATSUNLOCK(&entry->acache->stats.lock);
 
        ACACHE_UNLOCK(&acache->entrylocks[locknum], isc_rwlocktype_read);