From a241c69920fe5a609305fb435b593c2d997626aa Mon Sep 17 00:00:00 2001 From: Mark Andrews Date: Thu, 15 Oct 2020 15:05:30 +1100 Subject: [PATCH] Lock read of refs when atomics are not available. WARNING: ThreadSanitizer: data race Read of size 4 at 0x000000000001 by thread T1 (mutexes: write M1): #0 zone_iattach lib/dns/zone.c:5412:2 #1 soa_query lib/dns/zone.c:12725:2 #2 dispatch lib/isc/task.c:1157:7 #3 run lib/isc/task.c:1331:2 Previous write of size 4 at 0x000000000001 by thread T2 (mutexes: write M2): #0 dns_zone_detach lib/dns/zone.c:5346:2 #1 ns_server_refreshcommand bin/named/./server.c:9880:3 #2 ns_control_docommand bin/named/control.c:247:12 #3 control_recvmessage bin/named/controlconf.c:469:13 #4 dispatch lib/isc/task.c:1157:7 #5 run lib/isc/task.c:1331:2 Conflict: NA Reference: https://gitlab.isc.org/isc-projects/bind9/-/commit/a241c69920fe5a609305fb435b593c2d997626aa --- lib/isc/include/isc/refcount.h | 2 +- lib/isc/refcount.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/lib/isc/include/isc/refcount.h b/lib/isc/include/isc/refcount.h index 5d1a5d2bbf..1c9696fc6b 100644 --- a/lib/isc/include/isc/refcount.h +++ b/lib/isc/include/isc/refcount.h @@ -211,7 +211,7 @@ typedef struct isc_refcount { ISC_ERROR_RUNTIMECHECK(_result == ISC_R_SUCCESS); \ } while (0) -#define isc_refcount_current(rp) ((unsigned int)((rp)->refs)) +unsigned int isc_refcount_current(isc_refcount_t *rp); /*% * Increments the reference count, returning the new value in diff --git a/lib/isc/refcount.c b/lib/isc/refcount.c index d83c82fe7f..0d961effe1 100644 --- a/lib/isc/refcount.c +++ b/lib/isc/refcount.c @@ -19,6 +19,21 @@ #include #include +#if defined(ISC_PLATFORM_USETHREADS) && !defined(ISC_REFCOUNT_HAVEATOMIC) +unsigned int +isc_refcount_current(isc_refcount_t *ref) { + isc_result_t result; + unsigned int answer; + + result = isc_mutex_lock(&ref->lock); + ISC_ERROR_RUNTIMECHECK(result == ISC_R_SUCCESS); + answer = ref->refs; + result = isc_mutex_unlock(&ref->lock); + ISC_ERROR_RUNTIMECHECK(result == ISC_R_SUCCESS); + return (answer); +} +#endif + isc_result_t isc_refcount_init(isc_refcount_t *ref, unsigned int n) { REQUIRE(ref != NULL); -- 2.23.0