From 41b88e93375d57db12da923f45f87b9a2db8e730 Mon Sep 17 00:00:00 2001
From: Russell Yanofsky <russ@yanofsky.org>
Date: Wed, 8 Nov 2017 15:28:35 -0500
Subject: [PATCH] Add unit test for DEBUG_LOCKORDER code

---
 src/Makefile.test.include |  1 +
 src/sync.cpp              |  8 +++++++-
 src/sync.h                |  7 +++++++
 src/test/sync_tests.cpp   | 41 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 src/test/sync_tests.cpp

diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 6f401636f5..516059917c 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -81,6 +81,7 @@ BITCOIN_TESTS =\
   test/sigopcount_tests.cpp \
   test/skiplist_tests.cpp \
   test/streams_tests.cpp \
+  test/sync_tests.cpp \
   test/timedata_tests.cpp \
   test/torcontrol_tests.cpp \
   test/transaction_tests.cpp \
diff --git a/src/sync.cpp b/src/sync.cpp
index 28a4e37e68..96ea61b211 100644
--- a/src/sync.cpp
+++ b/src/sync.cpp
@@ -100,7 +100,11 @@ static void potential_deadlock_detected(const std::pair<void*, void*>& mismatch,
         }
         LogPrintf(" %s\n", i.second.ToString());
     }
-    assert(false);
+    if (g_debug_lockorder_abort) {
+        fprintf(stderr, "Assertion failed: detected inconsistent lock order at %s:%i, details in debug log.\n", __FILE__, __LINE__);
+        abort();
+    }
+    throw std::logic_error("potential deadlock detected");
 }
 
 static void push_lock(void* c, const CLockLocation& locklocation)
@@ -189,4 +193,6 @@ void DeleteLock(void* cs)
     }
 }
 
+bool g_debug_lockorder_abort = true;
+
 #endif /* DEBUG_LOCKORDER */
diff --git a/src/sync.h b/src/sync.h
index 882ad5dc4c..b8cb84f79f 100644
--- a/src/sync.h
+++ b/src/sync.h
@@ -77,6 +77,13 @@ std::string LocksHeld();
 void AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) ASSERT_EXCLUSIVE_LOCK(cs);
 void AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs);
 void DeleteLock(void* cs);
+
+/**
+ * Call abort() if a potential lock order deadlock bug is detected, instead of
+ * just logging information and throwing a logic_error. Defaults to true, and
+ * set to false in DEBUG_LOCKORDER unit tests.
+ */
+extern bool g_debug_lockorder_abort;
 #else
 void static inline EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false) {}
 void static inline LeaveCritical() {}
diff --git a/src/test/sync_tests.cpp b/src/test/sync_tests.cpp
new file mode 100644
index 0000000000..2e0951c3a9
--- /dev/null
+++ b/src/test/sync_tests.cpp
@@ -0,0 +1,41 @@
+// Copyright (c) 2012-2017 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <sync.h>
+#include <test/test_bitcoin.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(sync_tests, BasicTestingSetup)
+
+BOOST_AUTO_TEST_CASE(potential_deadlock_detected)
+{
+    #ifdef DEBUG_LOCKORDER
+    bool prev = g_debug_lockorder_abort;
+    g_debug_lockorder_abort = false;
+    #endif
+
+    CCriticalSection mutex1, mutex2;
+    {
+        LOCK2(mutex1, mutex2);
+    }
+    bool error_thrown = false;
+    try {
+        LOCK2(mutex2, mutex1);
+    } catch (const std::logic_error& e) {
+        BOOST_CHECK_EQUAL(e.what(), "potential deadlock detected");
+        error_thrown = true;
+    }
+    #ifdef DEBUG_LOCKORDER
+    BOOST_CHECK(error_thrown);
+    #else
+    BOOST_CHECK(!error_thrown);
+    #endif
+
+    #ifdef DEBUG_LOCKORDER
+    g_debug_lockorder_abort = prev;
+    #endif
+}
+
+BOOST_AUTO_TEST_SUITE_END()