From: Ondřej Surý <ondrej@isc.org>
Date: Thu, 19 Mar 2026 18:04:09 +0000 (+0100)
Subject: fix: dev: Fix data race in glue cache RCU pointer publication
X-Git-Tag: v9.21.21~25
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ea408e3c3db58699f402ab22c157f1ab1711fdc3;p=thirdparty%2Fbind9.git

fix: dev: Fix data race in glue cache RCU pointer publication

The liburcu rcu_cmpxchg_pointer() uses relaxed ordering on the CAS
failure path. When two threads race to publish a new pointer and one
loses the CAS, the returned pointer has no acquire semantics - reading
fields through it is a data race on weakly-ordered architectures.

Override rcu_cmpxchg_pointer() and rcu_xchg_pointer() to use
acquire/release ordering via standard __atomic builtins, which also
makes the operations natively visible to ThreadSanitizer.

Closes #5182

Merge branch '5182-fix-false-tsan-report-in-addglue' into 'main'

See merge request isc-projects/bind9!11719
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