fix: governance should not lock mempool mutex even call GetTransaction

GetTransaction is indeed called deep inside but the nullptr is pass
as a pointer to mempool. There is no used global mempool and GetTransaction
do not use any other mempool if argument with pointer to mempol is empty.

Author: knst

src/governance/governance.cpp

@@ -143,8 +143,7 @@ void CGovernanceManager::ProcessMessage(CNode& peer, std::string_view msg_type,
             return;
         }
 
-        LOCK2(cs_main, ::mempool.cs); // Lock mempool because of GetTransaction deep inside
-        LOCK(cs);
+        LOCK2(cs_main, cs);
 
         if (mapObjects.count(nHash) || mapPostponedObjects.count(nHash) || mapErasedGovernanceObjects.count(nHash)) {
             // TODO - print error code? what if it's GOVOBJ_ERROR_IMMATURE?
@@ -263,8 +262,7 @@ void CGovernanceManager::AddGovernanceObject(CGovernanceObject& govobj, CConnman
 
     govobj.UpdateSentinelVariables(); //this sets local vars in object
 
-    LOCK2(cs_main, ::mempool.cs); // Lock mempool because of GetTransaction deep inside
-    LOCK(cs);
+    LOCK2(cs_main, cs);
     std::string strError;
 
     // MAKE SURE THIS OBJECT IS OK
@@ -321,8 +319,7 @@ void CGovernanceManager::UpdateCachesAndClean()
 
     std::vector<uint256> vecDirtyHashes = mmetaman.GetAndClearDirtyGovernanceObjectHashes();
 
-    LOCK2(cs_main, ::mempool.cs); // Lock mempool because of GetTransaction deep inside
-    LOCK(cs);
+    LOCK2(cs_main, cs);
 
     for (const uint256& nHash : vecDirtyHashes) {
         auto it = mapObjects.find(nHash);
@@ -831,8 +828,7 @@ void CGovernanceManager::CheckPostponedObjects(CConnman& connman)
 {
     if (!::masternodeSync->IsSynced()) return;
 
-    LOCK2(cs_main, ::mempool.cs); // Lock mempool because of GetTransaction deep inside
-    LOCK(cs);
+    LOCK2(cs_main, cs);
 
     // Check postponed proposals
     for (auto it = mapPostponedObjects.begin(); it != mapPostponedObjects.end();) {

src/governance/object.cpp

@@ -531,7 +531,6 @@ CAmount CGovernanceObject::GetMinCollateralFee(bool fork_active) const
 bool CGovernanceObject::IsCollateralValid(std::string& strError, bool& fMissingConfirmations) const
 {
     AssertLockHeld(cs_main);
-    AssertLockHeld(::mempool.cs); // because of GetTransaction
 
     strError = "";
     fMissingConfirmations = false;