From: Ondřej Surý <ondrej@isc.org>
Date: Thu, 24 Jul 2025 09:02:15 +0000 (+0200)
Subject: Add rcu_barrier() to isc__log_shutdown()
X-Git-Tag: v9.21.11~11^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f2e107508a2a229336a4afe6a74784a255633509;p=thirdparty%2Fbind9.git

Add rcu_barrier() to isc__log_shutdown()

There is a data race when QP is reclaiming chunks on the call_rcu
threads and it tries to log the number of reclaimed chunks while the
server is shuttingdown.  Workaround this by adding rcu_barrier() before
shuttingdown the global log context.
---

diff --git a/lib/isc/log.c b/lib/isc/log.c
index d46054f4344..512e7247042 100644
--- a/lib/isc/log.c
+++ b/lib/isc/log.c
@@ -1573,6 +1573,14 @@ isc__log_initialize(void) {
 
 void
 isc__log_shutdown(void) {
+	/*
+	 * There is a data race when the QP database reclaims chunks on the
+	 * call_rcu threads and tries to log the number of reclaimed chunks
+	 * while the server is shutting down.  Work around this by adding
+	 * an rcu_barrier() before shutting down the global logging context.
+	 */
+	rcu_barrier();
+
 	REQUIRE(VALID_CONTEXT(isc__lctx));
 
 	isc_mem_t *mctx = isc__lctx->mctx;