From: Ondřej Surý <ondrej@isc.org>
Date: Wed, 26 Nov 2025 16:10:37 +0000 (+0100)
Subject: Use atomics for CMM_{LOAD,STORE}_SHARED with ThreadSanitizer
X-Git-Tag: v9.21.16~30^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=539be61b680572beb555e10f36e0b2c16caade50;p=thirdparty%2Fbind9.git

Use atomics for CMM_{LOAD,STORE}_SHARED with ThreadSanitizer

Upstream has removed the atomics implementation of CMM_LOAD_SHARED and
CMM_STORE_SHARED as these can be used also with non-stdatomics types.
As we only use the CMM api with stdatomics types, we can restore the
previous behaviour to prevent ThreadSanitizer warnings.
---

diff --git a/lib/isc/include/isc/urcu.h b/lib/isc/include/isc/urcu.h
index e2ed8557590..fc34fcf2653 100644
--- a/lib/isc/include/isc/urcu.h
+++ b/lib/isc/include/isc/urcu.h
@@ -141,3 +141,32 @@
 
 #endif /* !defined(caa_container_of_check_null) */
 /* clang-format on */
+
+#ifdef __SANITIZE_THREAD__
+
+/*
+ * Restore the behaviour removed in
+ * https://github.com/urcu/userspace-rcu/commit/5cd787d0f953182a23d340669b20b150fd50c18c
+ * as we only use CMM_LOAD_SHARED() and CMM_STORE_SHARED() with atomic types.
+ */
+
+#undef CMM_LOAD_SHARED
+#define CMM_LOAD_SHARED(x) \
+	__atomic_load_n(cmm_cast_volatile(&(x)), __ATOMIC_RELAXED)
+
+#undef _CMM_LOAD_SHARED
+#define _CMM_LOAD_SHARED(x) CMM_LOAD_SHARED(x)
+
+#undef CMM_STORE_SHARED
+#define CMM_STORE_SHARED(x, v)                                \
+	__extension__({                                       \
+		__typeof__(v) _v = (v);                       \
+		__atomic_store_n(cmm_cast_volatile(&(x)), _v, \
+				 __ATOMIC_RELAXED);           \
+		_v;                                           \
+	})
+
+#undef _CMM_STORE_SHARED
+#define _CMM_STORE_SHARED(x, v) CMM_STORE_SHARED(x, v)
+
+#endif