fix txLookupLock mutex leak on error returns in reorg

Author: ucwong

core/blockchain.go

@@ -2204,6 +2204,7 @@ func (bc *BlockChain) reorg(oldBlock, newBlock *types.Header) error {
 	// as the txlookups should be changed atomically, and all subsequent
 	// reads should be blocked until the mutation is complete.
 	bc.txLookupLock.Lock()
+	defer bc.txLookupLock.Unlock()
 
 	var (
 		deletedTxs []common.Hash
@@ -2314,9 +2315,6 @@ func (bc *BlockChain) reorg(oldBlock, newBlock *types.Header) error {
 	// Reset the tx lookup cache to clear stale txlookup cache.
 	bc.txLookupCache.Purge()
 
-	// Release the tx-lookup lock after mutation.
-	bc.txLookupLock.Unlock()
-
 	return nil
 }