Merge #11640: Make LOCK, LOCK2, TRY_LOCK work with CWaitableCriticalSection

9c4dc597dd Use LOCK macros for non-recursive locks (Russell Yanofsky)
1382913e61 Make LOCK, LOCK2, TRY_LOCK work with CWaitableCriticalSection (Russell Yanofsky)
ba1f095aad MOVEONLY Move AnnotatedMixin declaration (Russell Yanofsky)
41b88e9337 Add unit test for DEBUG_LOCKORDER code (Russell Yanofsky)

Pull request description:

  Make LOCK macros work with non-recursive mutexes, and use wherever possible for better deadlock detection.

  Also add unit test for DEBUG_LOCKORDER code.

Tree-SHA512: 64ef209307f28ecd0813a283f15c6406138c6ffe7f6cbbd084161044db60e2c099a7d0d2edcd1c5e7770a115e9b931b486e86c9a777bdc96d2e8a9f4dc192942

src/Makefile.test.include

@@ -83,6 +83,7 @@ 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 \

src/httpserver.cpp

@@ -69,7 +69,7 @@ class WorkQueue
 {
 private:
     /** Mutex protects entire object */
-    std::mutex cs;
+    CWaitableCriticalSection cs;
     std::condition_variable cond;
     std::deque<std::unique_ptr<WorkItem>> queue;
     bool running;
@@ -88,7 +88,7 @@ public:
     /** Enqueue a work item */
     bool Enqueue(WorkItem* item)
     {
-        std::unique_lock<std::mutex> lock(cs);
+        LOCK(cs);
         if (queue.size() >= maxDepth) {
             return false;
         }
@@ -102,7 +102,7 @@ public:
         while (true) {
             std::unique_ptr<WorkItem> i;
             {
-                std::unique_lock<std::mutex> lock(cs);
+                WAIT_LOCK(cs, lock);
                 while (running && queue.empty())
                     cond.wait(lock);
                 if (!running)
@@ -116,7 +116,7 @@ public:
     /** Interrupt and exit loops */
     void Interrupt()
     {
-        std::unique_lock<std::mutex> lock(cs);
+        LOCK(cs);
         running = false;
         cond.notify_all();
     }

src/init.cpp

@@ -568,7 +568,7 @@ static void BlockNotifyGenesisWait(bool, const CBlockIndex *pBlockIndex)
 {
     if (pBlockIndex != nullptr) {
         {
-            WaitableLock lock_GenesisWait(cs_GenesisWait);
+            LOCK(cs_GenesisWait);
             fHaveGenesis = true;
         }
         condvar_GenesisWait.notify_all();
@@ -1661,7 +1661,7 @@ bool AppInitMain()
 
     // Wait for genesis block to be processed
     {
-        WaitableLock lock(cs_GenesisWait);
+        WAIT_LOCK(cs_GenesisWait, lock);
         // We previously could hang here if StartShutdown() is called prior to
         // ThreadImport getting started, so instead we just wait on a timer to
         // check ShutdownRequested() regularly.

src/net.cpp

@@ -2065,7 +2065,7 @@ void CConnman::ThreadMessageHandler()
                 pnode->Release();
         }
 
-        std::unique_lock<std::mutex> lock(mutexMsgProc);
+        WAIT_LOCK(mutexMsgProc, lock);
         if (!fMoreWork) {
             condMsgProc.wait_until(lock, std::chrono::steady_clock::now() + std::chrono::milliseconds(100), [this] { return fMsgProcWake; });
         }
@@ -2347,7 +2347,7 @@ bool CConnman::Start(CScheduler& scheduler, const Options& connOptions)
     flagInterruptMsgProc = false;
 
     {
-        std::unique_lock<std::mutex> lock(mutexMsgProc);
+        LOCK(mutexMsgProc);
         fMsgProcWake = false;
     }
 

src/net.h

@@ -427,7 +427,7 @@ private:
     bool fMsgProcWake;
 
     std::condition_variable condMsgProc;
-    std::mutex mutexMsgProc;
+    CWaitableCriticalSection mutexMsgProc;
     std::atomic<bool> flagInterruptMsgProc;
 
     CThreadInterrupt interruptNet;

src/random.cpp

@@ -12,6 +12,7 @@
 #include <wincrypt.h>
 #endif
 #include <logging.h>  // for LogPrint()
+#include <sync.h>     // for WAIT_LOCK
 #include <utiltime.h> // for GetTime()
 
 #include <stdlib.h>
@@ -295,7 +296,7 @@ void RandAddSeedSleep()
 }
 
 
-static std::mutex cs_rng_state;
+static CWaitableCriticalSection cs_rng_state;
 static unsigned char rng_state[32] = {0};
 static uint64_t rng_counter = 0;
 
@@ -305,7 +306,7 @@ static void AddDataToRng(void* data, size_t len) {
     hasher.Write((const unsigned char*)data, len);
     unsigned char buf[64];
     {
-        std::unique_lock<std::mutex> lock(cs_rng_state);
+        WAIT_LOCK(cs_rng_state, lock);
         hasher.Write(rng_state, sizeof(rng_state));
         hasher.Write((const unsigned char*)&rng_counter, sizeof(rng_counter));
         ++rng_counter;
@@ -337,7 +338,7 @@ void GetStrongRandBytes(unsigned char* out, int num)
 
     // Combine with and update state
     {
-        std::unique_lock<std::mutex> lock(cs_rng_state);
+        WAIT_LOCK(cs_rng_state, lock);
         hasher.Write(rng_state, sizeof(rng_state));
         hasher.Write((const unsigned char*)&rng_counter, sizeof(rng_counter));
         ++rng_counter;

src/rpc/blockchain.cpp

@@ -50,7 +50,7 @@ struct CUpdatedBlock
     int height;
 };
 
-static std::mutex cs_blockchange;
+static CWaitableCriticalSection cs_blockchange;
 static std::condition_variable cond_blockchange;
 static CUpdatedBlock latestblock;
 
@@ -225,7 +225,7 @@ static UniValue waitfornewblock(const JSONRPCRequest& request)
 
     CUpdatedBlock block;
     {
-        std::unique_lock<std::mutex> lock(cs_blockchange);
+        WAIT_LOCK(cs_blockchange, lock);
         block = latestblock;
         if(timeout)
             cond_blockchange.wait_for(lock, std::chrono::milliseconds(timeout), [&block]{return latestblock.height != block.height || latestblock.hash != block.hash || !IsRPCRunning(); });
@@ -267,7 +267,7 @@ static UniValue waitforblock(const JSONRPCRequest& request)
 
     CUpdatedBlock block;
     {
-        std::unique_lock<std::mutex> lock(cs_blockchange);
+        WAIT_LOCK(cs_blockchange, lock);
         if(timeout)
             cond_blockchange.wait_for(lock, std::chrono::milliseconds(timeout), [&hash]{return latestblock.hash == hash || !IsRPCRunning();});
         else
@@ -310,7 +310,7 @@ static UniValue waitforblockheight(const JSONRPCRequest& request)
 
     CUpdatedBlock block;
     {
-        std::unique_lock<std::mutex> lock(cs_blockchange);
+        WAIT_LOCK(cs_blockchange, lock);
         if(timeout)
             cond_blockchange.wait_for(lock, std::chrono::milliseconds(timeout), [&height]{return latestblock.height >= height || !IsRPCRunning();});
         else

src/rpc/mining.cpp

@@ -470,7 +470,7 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
         {
             checktxtime = std::chrono::steady_clock::now() + std::chrono::minutes(1);
 
-            WaitableLock lock(g_best_block_mutex);
+            WAIT_LOCK(g_best_block_mutex, lock);
             while (g_best_block == hashWatchedChain && IsRPCRunning())
             {
                 if (g_best_block_cv.wait_until(lock, checktxtime) == std::cv_status::timeout)

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 */

src/sync.h

@@ -46,14 +46,42 @@ LEAVE_CRITICAL_SECTION(mutex); // no RAII
 //                           //
 ///////////////////////////////
 
+#ifdef DEBUG_LOCKORDER
+void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false);
+void LeaveCritical();
+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);
+
 /**
- * Template mixin that adds -Wthread-safety locking
+ * Call abort() if a potential lock order deadlock bug is detected, instead of
- * annotations to a subset of the mutex API.
+ * 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() {}
+void static inline AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) ASSERT_EXCLUSIVE_LOCK(cs) {}
+void static inline AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) {}
+void static inline DeleteLock(void* cs) {}
+#endif
+#define AssertLockHeld(cs) AssertLockHeldInternal(#cs, __FILE__, __LINE__, &cs)
+#define AssertLockNotHeld(cs) AssertLockNotHeldInternal(#cs, __FILE__, __LINE__, &cs)
+
+/**
+ * Template mixin that adds -Wthread-safety locking annotations and lock order
+ * checking to a subset of the mutex API.
  */
 template <typename PARENT>
 class LOCKABLE AnnotatedMixin : public PARENT
 {
 public:
+    ~AnnotatedMixin() {
+        DeleteLock((void*)this);
+    }
+
     void lock() EXCLUSIVE_LOCK_FUNCTION()
     {
         PARENT::lock();
@@ -68,36 +96,15 @@ public:
     {
         return PARENT::try_lock();
     }
-};
 
-#ifdef DEBUG_LOCKORDER
+    using UniqueLock = std::unique_lock<PARENT>;
-void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false);
+};
-void LeaveCritical();
-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);
-#else
-void static inline EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false) {}
-void static inline LeaveCritical() {}
-void static inline AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) ASSERT_EXCLUSIVE_LOCK(cs) {}
-void static inline AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) {}
-void static inline DeleteLock(void* cs) {}
-#endif
-#define AssertLockHeld(cs) AssertLockHeldInternal(#cs, __FILE__, __LINE__, &cs)
-#define AssertLockNotHeld(cs) AssertLockNotHeldInternal(#cs, __FILE__, __LINE__, &cs)
 
 /**
  * Wrapped mutex: supports recursive locking, but no waiting
  * TODO: We should move away from using the recursive lock by default.
  */
-class CCriticalSection : public AnnotatedMixin<std::recursive_mutex>
+typedef AnnotatedMixin<std::recursive_mutex> CCriticalSection;
-{
-public:
-    ~CCriticalSection() {
-        DeleteLock((void*)this);
-    }
-};
 
 /** Wrapped mutex: supports waiting but not recursive locking */
 typedef AnnotatedMixin<std::mutex> CWaitableCriticalSection;
@@ -105,27 +112,23 @@ typedef AnnotatedMixin<std::mutex> CWaitableCriticalSection;
 /** Just a typedef for std::condition_variable, can be wrapped later if desired */
 typedef std::condition_variable CConditionVariable;
 
-/** Just a typedef for std::unique_lock, can be wrapped later if desired */
-typedef std::unique_lock<std::mutex> WaitableLock;
-
 #ifdef DEBUG_LOCKCONTENTION
 void PrintLockContention(const char* pszName, const char* pszFile, int nLine);
 #endif
 
-/** Wrapper around std::unique_lock<CCriticalSection> */
+/** Wrapper around std::unique_lock style lock for Mutex. */
-class SCOPED_LOCKABLE CCriticalBlock
+template <typename Mutex, typename Base = typename Mutex::UniqueLock>
+class SCOPED_LOCKABLE CCriticalBlock : public Base
 {
 private:
-    std::unique_lock<CCriticalSection> lock;
-
     void Enter(const char* pszName, const char* pszFile, int nLine)
     {
-        EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()));
+        EnterCritical(pszName, pszFile, nLine, (void*)(Base::mutex()));
 #ifdef DEBUG_LOCKCONTENTION
-        if (!lock.try_lock()) {
+        if (!Base::try_lock()) {
             PrintLockContention(pszName, pszFile, nLine);
 #endif
-            lock.lock();
+            Base::lock();
 #ifdef DEBUG_LOCKCONTENTION
         }
 #endif
@@ -133,15 +136,15 @@ private:
 
     bool TryEnter(const char* pszName, const char* pszFile, int nLine)
     {
-        EnterCritical(pszName, pszFile, nLine, (void*)(lock.mutex()), true);
+        EnterCritical(pszName, pszFile, nLine, (void*)(Base::mutex()), true);
-        lock.try_lock();
+        Base::try_lock();
-        if (!lock.owns_lock())
+        if (!Base::owns_lock())
             LeaveCritical();
-        return lock.owns_lock();
+        return Base::owns_lock();
     }
 
 public:
-    CCriticalBlock(CCriticalSection& mutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(mutexIn) : lock(mutexIn, std::defer_lock)
+    CCriticalBlock(Mutex& mutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(mutexIn) : Base(mutexIn, std::defer_lock)
     {
         if (fTry)
             TryEnter(pszName, pszFile, nLine);
@@ -149,11 +152,11 @@ public:
             Enter(pszName, pszFile, nLine);
     }
 
-    CCriticalBlock(CCriticalSection* pmutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(pmutexIn)
+    CCriticalBlock(Mutex* pmutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(pmutexIn)
     {
         if (!pmutexIn) return;
 
-        lock = std::unique_lock<CCriticalSection>(*pmutexIn, std::defer_lock);
+        *static_cast<Base*>(this) = Base(*pmutexIn, std::defer_lock);
         if (fTry)
             TryEnter(pszName, pszFile, nLine);
         else
@@ -162,22 +165,28 @@ public:
 
     ~CCriticalBlock() UNLOCK_FUNCTION()
     {
-        if (lock.owns_lock())
+        if (Base::owns_lock())
             LeaveCritical();
     }
 
     operator bool()
     {
-        return lock.owns_lock();
+        return Base::owns_lock();
     }
 };
 
+template<typename MutexArg>
+using DebugLock = CCriticalBlock<typename std::remove_reference<typename std::remove_pointer<MutexArg>::type>::type>;
+
 #define PASTE(x, y) x ## y
 #define PASTE2(x, y) PASTE(x, y)
 
-#define LOCK(cs) CCriticalBlock PASTE2(criticalblock, __COUNTER__)(cs, #cs, __FILE__, __LINE__)
+#define LOCK(cs) DebugLock<decltype(cs)> PASTE2(criticalblock, __COUNTER__)(cs, #cs, __FILE__, __LINE__)
-#define LOCK2(cs1, cs2) CCriticalBlock criticalblock1(cs1, #cs1, __FILE__, __LINE__), criticalblock2(cs2, #cs2, __FILE__, __LINE__)
+#define LOCK2(cs1, cs2)                                               \
-#define TRY_LOCK(cs, name) CCriticalBlock name(cs, #cs, __FILE__, __LINE__, true)
+    DebugLock<decltype(cs1)> criticalblock1(cs1, #cs1, __FILE__, __LINE__); \
+    DebugLock<decltype(cs2)> criticalblock2(cs2, #cs2, __FILE__, __LINE__);
+#define TRY_LOCK(cs, name) DebugLock<decltype(cs)> name(cs, #cs, __FILE__, __LINE__, true)
+#define WAIT_LOCK(cs, name) DebugLock<decltype(cs)> name(cs, #cs, __FILE__, __LINE__)
 
 #define ENTER_CRITICAL_SECTION(cs)                            \
     {                                                         \

src/test/sync_tests.cpp

@@ -0,0 +1,52 @@
+// 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>
+
+namespace {
+template <typename MutexType>
+void TestPotentialDeadLockDetected(MutexType& mutex1, MutexType& 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
+}
+} // namespace
+
+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 rmutex1, rmutex2;
+    TestPotentialDeadLockDetected(rmutex1, rmutex2);
+
+    CWaitableCriticalSection mutex1, mutex2;
+    TestPotentialDeadLockDetected(mutex1, mutex2);
+
+    #ifdef DEBUG_LOCKORDER
+    g_debug_lockorder_abort = prev;
+    #endif
+}
+
+BOOST_AUTO_TEST_SUITE_END()

src/threadinterrupt.cpp

@@ -5,6 +5,8 @@
 
 #include <threadinterrupt.h>
 
+#include <sync.h>
+
 CThreadInterrupt::CThreadInterrupt() : flag(false) {}
 
 CThreadInterrupt::operator bool() const
@@ -20,7 +22,7 @@ void CThreadInterrupt::reset()
 void CThreadInterrupt::operator()()
 {
     {
-        std::unique_lock<std::mutex> lock(mut);
+        LOCK(mut);
         flag.store(true, std::memory_order_release);
     }
     cond.notify_all();
@@ -28,7 +30,7 @@ void CThreadInterrupt::operator()()
 
 bool CThreadInterrupt::sleep_for(std::chrono::milliseconds rel_time)
 {
-    std::unique_lock<std::mutex> lock(mut);
+    WAIT_LOCK(mut, lock);
     return !cond.wait_for(lock, rel_time, [this]() { return flag.load(std::memory_order_acquire); });
 }
 

src/threadinterrupt.h

@@ -5,6 +5,8 @@
 #ifndef BITCOIN_THREADINTERRUPT_H
 #define BITCOIN_THREADINTERRUPT_H
 
+#include <sync.h>
+
 #include <atomic>
 #include <chrono>
 #include <condition_variable>
@@ -28,7 +30,7 @@ public:
 
 private:
     std::condition_variable cond;
-    std::mutex mut;
+    CWaitableCriticalSection mut;
     std::atomic<bool> flag;
 };
 

src/validation.cpp

@@ -2239,7 +2239,7 @@ void static UpdateTip(const CBlockIndex *pindexNew, const CChainParams& chainPar
     mempool.AddTransactionsUpdated(1);
 
     {
-        WaitableLock lock(g_best_block_mutex);
+        LOCK(g_best_block_mutex);
         g_best_block = pindexNew->GetBlockHash();
         g_best_block_cv.notify_all();
     }