Make iSCSI connection close somewhat less aggressive.

It allows to push out some final data from the send queue to the socket
before its close.  In particular, it increases chances for logout response
to be delivered to the initiator.

sys/cam/ctl/ctl_frontend_iscsi.c

@@ -1135,7 +1135,6 @@ cfiscsi_maintenance_thread(void *arg)
 			 * that anymore.  We might need to revisit that.
 			 */
 			callout_drain(&cs->cs_callout);
-			icl_conn_shutdown(cs->cs_conn);
 			icl_conn_close(cs->cs_conn);
 
 			/*

sys/dev/iscsi/icl.c

@@ -873,8 +873,6 @@ icl_conn_send_pdus(struct icl_conn *ic, struct icl_pdu_stailq *queue)
 	SOCKBUF_UNLOCK(&so->so_snd);
 
 	while (!STAILQ_EMPTY(queue)) {
-		if (ic->ic_disconnecting)
-			return;
 		request = STAILQ_FIRST(queue);
 		size = icl_pdu_size(request);
 		if (available < size) {
@@ -971,11 +969,6 @@ icl_send_thread(void *arg)
 	ic->ic_send_running = true;
 
 	for (;;) {
-		if (ic->ic_disconnecting) {
-			//ICL_DEBUG("terminating");
-			break;
-		}
-
 		for (;;) {
 			/*
 			 * If the local queue is empty, populate it from
@@ -1014,6 +1007,11 @@ icl_send_thread(void *arg)
 			break;
 		}
 
+		if (ic->ic_disconnecting) {
+			//ICL_DEBUG("terminating");
+			break;
+		}
+
 		cv_wait(&ic->ic_send_cv, ic->ic_lock);
 	}
 
@@ -1297,21 +1295,6 @@ icl_conn_handoff(struct icl_conn *ic, int fd)
 	return (error);
 }
 
-void
-icl_conn_shutdown(struct icl_conn *ic)
-{
-	ICL_CONN_LOCK_ASSERT_NOT(ic);
-
-	ICL_CONN_LOCK(ic);
-	if (ic->ic_socket == NULL) {
-		ICL_CONN_UNLOCK(ic);
-		return;
-	}
-	ICL_CONN_UNLOCK(ic);
-
-	soshutdown(ic->ic_socket, SHUT_RDWR);
-}
-
 void
 icl_conn_close(struct icl_conn *ic)
 {

sys/dev/iscsi/icl.h

@@ -107,7 +107,6 @@ struct icl_conn {
 struct icl_conn		*icl_conn_new(const char *name, struct mtx *lock);
 void			icl_conn_free(struct icl_conn *ic);
 int			icl_conn_handoff(struct icl_conn *ic, int fd);
-void			icl_conn_shutdown(struct icl_conn *ic);
 void			icl_conn_close(struct icl_conn *ic);
 bool			icl_conn_connected(struct icl_conn *ic);
 

sys/dev/iscsi/iscsi.c

@@ -367,7 +367,6 @@ static void
 iscsi_maintenance_thread_reconnect(struct iscsi_session *is)
 {
 
-	icl_conn_shutdown(is->is_conn);
 	icl_conn_close(is->is_conn);
 
 	ISCSI_SESSION_LOCK(is);