From 638561615c37e8eace986e268811335c12d1b6a1 Mon Sep 17 00:00:00 2001

From: Mark Andrews <marka@isc.org>

Date: Thu, 12 Dec 2019 20:41:44 +1100

Subject: [PATCH] give zspill its own lock

(cherry picked from commit a52189e8e67a20097539fe3e6f7da4e4c01dc340)

---

 lib/dns/resolver.c | 45 +++++++++++++++++++++++++++++----------------

 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c

index 9f65c0596a..04367f82c6 100644

--- a/lib/dns/resolver.c

+++ b/lib/dns/resolver.c

@@ -460,20 +460,21 @@ struct dns_resolver {

 	isc_mutex_t			lock;

 	isc_mutex_t			nlock;

 	isc_mutex_t			primelock;

+	isc_mutex_t			zspill_lock;

 	dns_rdataclass_t		rdclass;

 	isc_socketmgr_t *		socketmgr;

 	isc_timermgr_t *		timermgr;

 	isc_taskmgr_t *			taskmgr;

 	dns_view_t *			view;

-	bool			frozen;

+	bool				frozen;

 	unsigned int			options;

 	dns_dispatchmgr_t *		dispatchmgr;

 	dns_dispatchset_t *		dispatches4;

-	bool			exclusivev4;

+	bool				exclusivev4;

 	dns_dispatchset_t *		dispatches6;

 	isc_dscp_t			querydscp4;

 	isc_dscp_t			querydscp6;

-	bool			exclusivev6;

+	bool				exclusivev6;

 	unsigned int			nbuckets;

 	fctxbucket_t *			buckets;

 	zonebucket_t *			dbuckets;

@@ -492,7 +493,7 @@ struct dns_resolver {

 	unsigned int			spillatmax;

 	unsigned int			spillatmin;

 	isc_timer_t *			spillattimer;

-	bool			zero_no_soa_ttl;

+	bool				zero_no_soa_ttl;

 	unsigned int			query_timeout;

 	unsigned int			maxdepth;

 	unsigned int			maxqueries;

@@ -502,14 +503,16 @@ struct dns_resolver {

 	unsigned int			retryinterval; /* in milliseconds */

 	unsigned int			nonbackofftries;

+	/* Locked by lock. */

+	unsigned int			zspill;		/* fetches-per-zone */

+

 	/* Locked by lock. */

 	unsigned int			references;

-	bool			exiting;

+	bool				exiting;

 	isc_eventlist_t			whenshutdown;

 	unsigned int			activebuckets;

-	bool			priming;

+	bool				priming;

 	unsigned int			spillat;	/* clients-per-query */

-	unsigned int			zspill;		/* fetches-per-zone */

 	dns_badcache_t  * 		badcache;	 /* Bad cache. */

@@ -1257,7 +1260,7 @@ fcount_incr(fetchctx_t *fctx, bool force) {

 	isc_result_t result = ISC_R_SUCCESS;

 	zonebucket_t *dbucket;

 	fctxcount_t *counter;

-	unsigned int bucketnum, spill;

+	unsigned int bucketnum;

 	REQUIRE(fctx != NULL);

 	REQUIRE(fctx->res != NULL);

@@ -1266,10 +1269,6 @@ fcount_incr(fetchctx_t *fctx, bool force) {

 	bucketnum = dns_name_fullhash(&fctx->domain, false)

 			% RES_DOMAIN_BUCKETS;

-	LOCK(&fctx->res->lock);

-	spill = fctx->res->zspill;

-	UNLOCK(&fctx->res->lock);

-

 	dbucket = &fctx->res->dbuckets[bucketnum];

 	LOCK(&dbucket->lock);

@@ -1297,6 +1296,12 @@ fcount_incr(fetchctx_t *fctx, bool force) {

 			ISC_LIST_APPEND(dbucket->list, counter, link);

 		}

 	} else {

+		unsigned int spill;

+

+		LOCK(&fctx->res->zspill_lock);

+		spill = fctx->res->zspill;

+		UNLOCK(&fctx->res->zspill_lock);

+

 		if (!force && spill != 0 && counter->count >= spill) {

 			counter->dropped++;

 			fcount_logspill(fctx, counter);

@@ -8811,6 +8816,7 @@ destroy(dns_resolver_t *res) {

 	INSIST(res->nfctx == 0);

+	DESTROYLOCK(&res->zspill_lock);

 	DESTROYLOCK(&res->primelock);

 	DESTROYLOCK(&res->nlock);

 	DESTROYLOCK(&res->lock);

@@ -9089,10 +9095,14 @@ dns_resolver_create(dns_view_t *view,

 	if (result != ISC_R_SUCCESS)

 		goto cleanup_nlock;

+	result = isc_mutex_init(&res->zspill_lock);

+	if (result != ISC_R_SUCCESS)

+		goto cleanup_primelock;

+

 	task = NULL;

 	result = isc_task_create(taskmgr, 0, &task);

 	if (result != ISC_R_SUCCESS)

-		goto cleanup_primelock;

+		goto cleanup_zspill_lock;

 	isc_task_setname(task, "resolver_task", NULL);

 	result = isc_timer_create(timermgr, isc_timertype_inactive, NULL, NULL,

@@ -9100,7 +9110,7 @@ dns_resolver_create(dns_view_t *view,

 				  &res->spillattimer);

 	isc_task_detach(&task);

 	if (result != ISC_R_SUCCESS)

-		goto cleanup_primelock;

+		goto cleanup_zspill_lock;

 #if USE_ALGLOCK

 	result = isc_rwlock_init(&res->alglock, 0, 0);

@@ -9133,6 +9143,9 @@ dns_resolver_create(dns_view_t *view,

 	isc_timer_detach(&res->spillattimer);

 #endif

+ cleanup_zspill_lock:

+	DESTROYLOCK(&res->zspill_lock);

+

  cleanup_primelock:

 	DESTROYLOCK(&res->primelock);

@@ -10275,9 +10288,9 @@ dns_resolver_setfetchesperzone(dns_resolver_t *resolver, uint32_t clients)

 {

 	REQUIRE(VALID_RESOLVER(resolver));

-	LOCK(&resolver->lock);

+	LOCK(&resolver->zspill_lock);

 	resolver->zspill = clients;

-	UNLOCK(&resolver->lock);

+	UNLOCK(&resolver->zspill_lock);

 }

-- 

2.21.0