Remove the DB lock, its unnecessary

src/networking.cpp

@@ -3003,7 +3003,6 @@ int processEventsWhileBlocked(int iel) {
     {
         serverAssert(c->flags & CLIENT_PROTECTED);
         c->lock.unlock();
-        c->db->lock.unlock();
     }
     aeReleaseLock();
     while (iterations--) {
@@ -3017,8 +3016,6 @@ int processEventsWhileBlocked(int iel) {
     if (c != nullptr)
         c->lock.lock();
     locker.arm(c);
-    if (c != nullptr)
-        c->db->lock.lock();
     locker.release();
     return count;
 }

src/server.cpp

@@ -3704,7 +3704,6 @@ int processCommand(client *c, int callFlags) {
         queueMultiCommand(c);
         addReply(c,shared.queued);
     } else {
-        std::unique_lock<decltype(c->db->lock)> ulock(c->db->lock);
         call(c,callFlags);
         c->woff = g_pserver->master_repl_offset;
         if (listLength(g_pserver->ready_keys))

src/server.h

@@ -1044,7 +1044,7 @@ typedef struct clientReplyBlock {
  * database. The database number is the 'id' field in the structure. */
 typedef struct redisDb {
     redisDb() 
-        : expireitr(nullptr), lock("redisDB")
+        : expireitr(nullptr)
     {};
     dict *pdict;                 /* The keyspace for this DB */
     expireset *setexpire;
@@ -1057,8 +1057,6 @@ typedef struct redisDb {
     long long last_expire_set;  /* when the last expire was set */
     double avg_ttl;             /* Average TTL, just for stats */
     list *defrag_later;         /* List of key names to attempt to defrag one by one, gradually. */
-
-    fastlock lock;
 } redisDb;
 
 /* Client MULTI/EXEC state */