Unify DCB close processing to single function dcb_close. Remove dcb_add_to_zombieslist (incorporating logic into dcb_close). Alter logic so that DCB that is just allocated will still go to zombie list if dcb->fd is not closed.

server/core/dcb.c

@@ -248,50 +248,6 @@ dcb_free(DCB *dcb)
 	}
 }
 
-/** 
- * Add the DCB to the end of zombies list. 
- *
- * Adding to list occurs once per DCB. This is ensured by changing the
- * state of DCB to DCB_STATE_ZOMBIE after addition. Prior insertion, DCB state
- * is checked and operation proceeds only if state differs from DCB_STATE_ZOMBIE.
- * @param dcb The DCB to add to the zombie list
- * @return none
- */
-void
-dcb_add_to_zombieslist(DCB *dcb)
-{
-        bool        succp = false;
-        dcb_state_t prev_state = DCB_STATE_UNDEFINED;
-        
-        CHK_DCB(dcb);        
-
-        /*<
-         * Protect zombies list access.
-         */
-	spinlock_acquire(&zombiespin);
-        /*<
-         * If dcb is already added to zombies list, return.
-         */
-        if (dcb->state != DCB_STATE_NOPOLLING) {
-                ss_dassert(dcb->state != DCB_STATE_POLLING &&
-                           dcb->state != DCB_STATE_LISTENING);
-                spinlock_release(&zombiespin);
-                return;
-        }
-        /*<
-         * Add closing dcb to the top of the list.
-         */
-        dcb->memdata.next = zombies;
-        zombies = dcb;
-        /*<
-         * Set state which indicates that it has been added to zombies
-         * list.
-         */
-        dcb->state = DCB_STATE_ZOMBIE;
-        
-	spinlock_release(&zombiespin);
-}
-
 /*
  * Clone a DCB for internal use, mostly used for specialist filters
  * to create dummy clients based on real clients.
@@ -600,7 +556,6 @@ bool    succp = false;
 			&tls_log_info.li_enabled_logs)));
 
                 dcb->state = DCB_STATE_DISCONNECTED;
-                ss_dassert(succp);
 		dcb_next = dcb->memdata.next;
                 dcb_final_free(dcb);
                 dcb = dcb_next;
@@ -1928,72 +1883,91 @@ dcb_drain_writeq_SSL(DCB *dcb)
 void
 dcb_close(DCB *dcb)
 {
-        int  rc = 0;
+    int  rc = 0;
 
-        CHK_DCB(dcb);
+    CHK_DCB(dcb);
 
-	LOGIF(LD, (skygw_log_write(LOGFILE_DEBUG,
+    LOGIF(LD, (skygw_log_write(LOGFILE_DEBUG,
-				"%lu [dcb_close]",
+        "%lu [dcb_close]",
-				pthread_self())));                                
+        pthread_self())));                                
-	
+
-        /**
+    if (DCB_STATE_UNDEFINED == dcb->state
-         * dcb_close may be called for freshly created dcb, in which case
+        || DCB_STATE_DISCONNECTED == dcb->state
-         * it only needs to be freed.
+        || DCB_STATE_ZOMBIE == dcb->state)
-         */
+    {
-        if (dcb->state == DCB_STATE_ALLOC)
+        LOGIF(LE, (skygw_log_write(
+            LOGFILE_ERROR,
+            "%lu [dcb_close] Error : Removing DCB %p but was in state %s "
+            "which is not legal for a call to dcb_close. ",
+            pthread_self(),
+            dcb,
+            STRDCBSTATE(dcb->state))));
+        assert(false);
+    }
+    
+    /**
+     * dcb_close may be called for freshly created dcb, in which case
+     * it only needs to be freed.
+     */
+    if (dcb->state == DCB_STATE_ALLOC && dcb->fd != DCBFD_CLOSED)
+    {
+        dcb_final_free(dcb);
+        return;
+    }
+        
+    /*<
+     * Stop dcb's listening and modify state accordingly.
+     */
+    if (dcb->state == DCB_STATE_POLLING  || dcb->state == DCB_STATE_LISTENING)
+    {
+        if (dcb->state == DCB_STATE_LISTENING)
         {
-                dcb_final_free(dcb);
+            LOGIF(LE, (skygw_log_write(
-                return;
+                LOGFILE_ERROR,
+                "%lu [dcb_close] Error : Removing DCB %p but was in state %s "
+                "which is not expected for a call to dcb_close, although it"
+                "should be processed correctly. ",
+                pthread_self(),
+                dcb,
+                STRDCBSTATE(dcb->state))));
         }
+        rc = poll_remove_dcb(dcb);
+        /*
+         * Return will always be 0 or function will have crashed
+         */
+        LOGIF(LD, (skygw_log_write(
+            LOGFILE_DEBUG,
+            "%lu [dcb_close] Removed dcb %p in state %s from "
+            "poll set.",
+            pthread_self(),
+            dcb,
+            STRDCBSTATE(dcb->state))));
+        /**
+         * close protocol and router session
+         */
+        if (dcb->func.close != NULL)
+        {
+            dcb->func.close(dcb);
+        }
+        /** Call possible callback for this DCB in case of close */
+        dcb_call_callback(dcb, DCB_REASON_CLOSE);
+    }
+    assert (dcb->state == DCB_STATE_NOPOLLING  || dcb->state == DCB_STATE_ALLOC);
+    
+    spinlock_acquire(&zombiespin);
+    
+    /*<
+     * Add closing dcb to the top of the list.
+     */
+    dcb->memdata.next = zombies;
+    zombies = dcb;
+    /*<
+     * Set state which indicates that it has been added to zombies
+     * list.
+     */
+    dcb->state = DCB_STATE_ZOMBIE;
         
-        ss_dassert(dcb->state == DCB_STATE_POLLING ||
+    spinlock_release(&zombiespin);
-               dcb->state == DCB_STATE_NOPOLLING ||
-               dcb->state == DCB_STATE_ZOMBIE);
-        
-        /*<
-        * Stop dcb's listening and modify state accordingly.
-        */
-	if (dcb->state == DCB_STATE_POLLING)
-	{
-		rc = poll_remove_dcb(dcb);
-
-		if (rc == 0) {
-			LOGIF(LD, (skygw_log_write(
-				LOGFILE_DEBUG,
-				"%lu [dcb_close] Removed dcb %p in state %s from "
-				"poll set.",
-				pthread_self(),
-				dcb,
-				STRDCBSTATE(dcb->state))));
-		} else {
-			LOGIF(LE, (skygw_log_write(
-				LOGFILE_ERROR,
-				"Error : Removing DCB fd == %d in state %s from "
-				"poll set failed.",
-				dcb->fd,
-				STRDCBSTATE(dcb->state))));
-		}
-	
-		if (rc == 0)
-		{
-			/**
-			 * close protocol and router session
-			 */
-			if (dcb->func.close != NULL)
-			{
-				dcb->func.close(dcb);
-			}
-			/** Call possible callback for this DCB in case of close */
-			dcb_call_callback(dcb, DCB_REASON_CLOSE);
-			
-			if (dcb->state == DCB_STATE_NOPOLLING) 
-			{
-				dcb_add_to_zombieslist(dcb);
-			}
-		}
-	        ss_dassert(dcb->state == DCB_STATE_NOPOLLING ||
-					dcb->state == DCB_STATE_ZOMBIE);	
-	}
 }
 
 /**

server/core/poll.c

@@ -302,10 +302,6 @@ poll_add_dcb(DCB *dcb)
                 dcb,
                 STRDCBSTATE(dcb->state))));
         }
-        /*<
-         * If dcb is in unexpected state, state change fails indicating that dcb
-         * is not polling anymore.
-         */
         dcb->state = new_state; 
         spinlock_release(&dcb->dcb_initlock);
         /*

server/core/test/testdcb.c

@@ -64,7 +64,7 @@ int     buflen;
         ss_info_dassert(!dcb_isvalid(dcb), "Freed DCB must not be valid");
         ss_dfprintf(stderr, "\t..done\nMake clone DCB a zombie");
         clone->state = DCB_STATE_NOPOLLING;
-        dcb_add_to_zombieslist(clone);
+        dcb_close(clone);
         ss_info_dassert(dcb_get_zombies() == clone, "Clone DCB must be start of zombie list now");
         ss_dfprintf(stderr, "\t..done\nProcess the zombies list");
         dcb_process_zombies(0);

server/include/dcb.h

@@ -330,7 +330,6 @@ const char 	*gw_dcb_state2string(int);		/* DCB state to string */
 void		dcb_printf(DCB *, const char *, ...);	/* DCB version of printf */
 int		dcb_isclient(DCB *);			/* the DCB is the client of the session */
 void		dcb_hashtable_stats(DCB *, void *);	/**< Print statisitics */
-void            dcb_add_to_zombieslist(DCB* dcb);
 int		dcb_add_callback(DCB *, DCB_REASON, int	(*)(struct dcb *, DCB_REASON, void *),
 			 void *);
 int		dcb_remove_callback(DCB *, DCB_REASON, int (*)(struct dcb *, DCB_REASON, void *),

server/modules/protocol/maxscaled.c

@@ -270,9 +270,7 @@ int	n_connect = 0;
 		{
 			atomic_add(&dcb->stats.n_accepts, 1);
                         client_dcb = dcb_alloc(DCB_ROLE_REQUEST_HANDLER);
-
 			if (client_dcb == NULL)
-
 			{
 				close(so);
 				return n_connect;
@@ -283,7 +281,8 @@ int	n_connect = 0;
                         if ((maxscaled_pr = (MAXSCALED *)malloc(sizeof(MAXSCALED))) == NULL)
 			{
                         	client_dcb->protocol = NULL;
-                                dcb_add_to_zombieslist(client_dcb);
+                                close(so);
+                                dcb_close(client_dcb);
 				return n_connect;
 			}
 			maxscaled_pr->username = NULL;
@@ -293,9 +292,9 @@ int	n_connect = 0;
 			client_dcb->session =
                                 session_alloc(dcb->session->service, client_dcb);
 
-			if (poll_add_dcb(client_dcb) == -1)
+			if (poll_add_dcb(client_dcb))
 			{
-                                dcb_add_to_zombieslist(dcb);
+                                dcb_close(dcb);
 				return n_connect;
 			}
 			n_connect++;

server/modules/protocol/telnetd.c

@@ -315,13 +315,13 @@ int	n_connect = 0;
 
                         if (telnetd_pr == NULL)
                         {
-                                dcb_add_to_zombieslist(client_dcb);
+                                dcb_close(client_dcb);
 				return n_connect;
 			}
 
-			if (poll_add_dcb(client_dcb) == -1)
+			if (poll_add_dcb(client_dcb))
 			{
-                                dcb_add_to_zombieslist(dcb);
+                                dcb_close(dcb);
 				return n_connect;
 			}
 			n_connect++;