Qutex: Add currOwner pointer for debugging

We'll use this to detect gridlock-type deadlocks between
two requests

include/qutex.h

@@ -28,7 +28,7 @@ public:
 	Qutex([[maybe_unused]] const std::string &_name)
 	:
 #ifdef CONFIG_ENABLE_DEBUG_LOCKS
-	name(_name),
+	name(_name), currOwner(nullptr),
 #endif
 	isOwned(false)
 	{}
@@ -92,6 +92,7 @@ public:
 public:
 #ifdef CONFIG_ENABLE_DEBUG_LOCKS
 	std::string name;
+	LockerAndInvokerBase* currOwner;
 #endif
 	SpinLock lock;
 	LockerAndInvokerBase::List queue;

smocore/qutex.cpp

@@ -43,6 +43,9 @@ bool Qutex::tryAcquire(
 	if (qNItems == 1 || nRearItemsToScan < 1)
 	{
 		isOwned = true;
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+		currOwner = const_cast<LockerAndInvokerBase*>(&tryingLockvoker);
+#endif
 		lock.release();
 		return true;
 	}
@@ -55,6 +58,9 @@ bool Qutex::tryAcquire(
 		if ((*queue.front()) == tryingLockvoker)
 		{
 			isOwned = true;
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+			currOwner = const_cast<LockerAndInvokerBase*>(&tryingLockvoker);
+#endif
 			ret = true;
 		}
 		else {
@@ -89,6 +95,9 @@ bool Qutex::tryAcquire(
 
 	// Not found in rear portion - must be in top X%, so succeed
 	isOwned = true;
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+	currOwner = const_cast<LockerAndInvokerBase*>(&tryingLockvoker);
+#endif
 	lock.release();
 	return true;
 }
@@ -220,6 +229,9 @@ void Qutex::backoff(
 	}
 
 	isOwned = false;
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+	currOwner = nullptr;
+#endif
 	LockerAndInvokerBase &newFront = *queue.front();
 
 	lock.release();
@@ -280,6 +292,9 @@ void Qutex::release()
 	lock.acquire();
 
 	isOwned = false;
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+	currOwner = nullptr;
+#endif
 
 	// It's possible for there to be 0 items left in queue after unregistering.
 	if (queue.empty())