From: Andres Freund <andres@anarazel.de>
Date: Fri, 14 Nov 2014 15:58:00 +0000 (+0100)
Subject: Add valgrind suppression for pg_atomic_init_u64.
X-Git-Tag: REL9_5_ALPHA1~1215
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6c878edc1df9d4d9ad7ed4a7e1c34c0bf0f622b9;p=postgresql

Add valgrind suppression for pg_atomic_init_u64.

pg_atomic_init_u64 (indirectly) uses compare/exchange to guarantee
atomic writes on platforms where compare/exchange is available, but
64bit writes aren't atomic (yes, those exist). That leads to a
harmless read of the initial value of variable.
---

diff --git a/src/tools/valgrind.supp b/src/tools/valgrind.supp
index 4721c0a6fb..0df95eabf1 100644
--- a/src/tools/valgrind.supp
+++ b/src/tools/valgrind.supp
@@ -104,3 +104,16 @@
 
 	fun:IsBinaryCoercible
 }
+
+# Atomic writes to 64bit atomic vars uses compare/exchange to
+# guarantee atomic writes of 64bit variables. pg_atomic_write is used
+# during initialization of the atomic variable, hat leads to an
+# initial read of the old, undefined, memory value. But that's just to
+# make sure the swap works correctly.
+{
+	uninitialized_atomic_init_u64
+	Memcheck:Cond
+	fun:pg_atomic_exchange_u64_impl
+	fun:pg_atomic_write_u64_impl
+	fun:pg_atomic_init_u64_impl
+}