From: Evan Hunt <each@isc.org>
Date: Tue, 28 Nov 2023 23:05:55 +0000 (-0800)
Subject: release RCU in dns_qpmulti_snapshot()
X-Git-Tag: v9.19.22~4^2~9
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2222728a4f6f5bbdceadfc7c6d156d37391b989f;p=thirdparty%2Fbind9.git

release RCU in dns_qpmulti_snapshot()

previously, an RCU critical section was held open for the duration
of a snapshot. this should not be necessary, as the snapshot makes
local copies of QP trie metadata, and it causes problems when a
DB iterator is held open between two loop events.  we now call
rcu_read_unlock() after setting up the snapshot.
---

diff --git a/lib/dns/qp.c b/lib/dns/qp.c
index 4ea05e09683..4e70fa0dac4 100644
--- a/lib/dns/qp.c
+++ b/lib/dns/qp.c
@@ -1391,6 +1391,8 @@ dns_qpmulti_snapshot(dns_qpmulti_t *multi, dns_qpsnap_t **qpsp) {
 
 	*qpsp = qps;
 	UNLOCK(&multi->mutex);
+
+	rcu_read_unlock();
 }
 
 void
@@ -1417,8 +1419,6 @@ dns_qpsnap_destroy(dns_qpmulti_t *multi, dns_qpsnap_t **qpsp) {
 
 	*qpsp = NULL;
 	UNLOCK(&multi->mutex);
-
-	rcu_read_unlock();
 }
 
 /***********************************************************************