netconn: switch gethostbyname to use tcpip_send_msg_wait_sem (task #14523)

This switches netconn_gethostbyname to use tcpip_send_msg_wait_sem to
take advantage of core locking support when enabled.

tcpip_send_msg_wait_sem handles blocking for the non-core locking case,
so we can remove the manual blocking in netconn_gethostbyname. For the
core locking case, we need to block if waiting on DNS callback. To
achieve this, we unlock the core and wait in lwip_netconn_do_gethostbyname.
This is the similar approach that netconn_write takes when it needs to
block to continue the write (see lwip_netconn_do_write)

This improves performance in the core locking case and is no change
for the non-core locking case

CHANGELOG

@@ -6,6 +6,9 @@ HISTORY
 
   ++ New features:
 
+  2017-06-20: Joel Cunningham
+  * netconn/netdb: added core locking support to netconn_gethostbyname (task #14523)
+
   2017-04-25: Simon Goldschmidt
   * dhcp: added two hooks for adding and parsing user defined DHCP options
 

src/api/api_lib.c

@@ -1184,18 +1184,14 @@ netconn_gethostbyname(const char *name, ip_addr_t *addr)
   }
 #endif /* LWIP_NETCONN_SEM_PER_THREAD */
 
-  cberr = tcpip_callback(lwip_netconn_do_gethostbyname, &API_VAR_REF(msg));
-  if (cberr != ERR_OK) {
+  cberr = tcpip_send_msg_wait_sem(lwip_netconn_do_gethostbyname, &API_VAR_REF(msg), API_EXPR_REF(API_VAR_REF(msg).sem));
 #if !LWIP_NETCONN_SEM_PER_THREAD
-    sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
+  sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
 #endif /* !LWIP_NETCONN_SEM_PER_THREAD */
+  if (cberr != ERR_OK) {
     API_VAR_FREE(MEMP_DNS_API_MSG, msg);
     return cberr;
   }
-  sys_sem_wait(API_EXPR_REF_SEM(API_VAR_REF(msg).sem));
-#if !LWIP_NETCONN_SEM_PER_THREAD
-  sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
-#endif /* !LWIP_NETCONN_SEM_PER_THREAD */
 
 #if LWIP_MPU_COMPATIBLE
   *addr = msg->addr;

src/api/api_msg.c

@@ -2042,11 +2042,21 @@ lwip_netconn_do_gethostbyname(void *arg)
 
   API_EXPR_DEREF(msg->err) = dns_gethostbyname_addrtype(msg->name,
     API_EXPR_REF(msg->addr), lwip_netconn_do_dns_found, msg, addrtype);
+#if LWIP_TCPIP_CORE_LOCKING
+  /* For core locking, only block if we need to wait for answer/timeout */
+  if (API_EXPR_DEREF(msg->err) == ERR_INPROGRESS) {
+    UNLOCK_TCPIP_CORE();
+    sys_sem_wait(API_EXPR_REF_SEM(msg->sem));
+    LOCK_TCPIP_CORE();
+    LWIP_ASSERT("do_gethostbyname still in progress!!", API_EXPR_DEREF(msg->err) != ERR_INPROGRESS);
+  }
+#else /* LWIP_TCPIP_CORE_LOCKING */
   if (API_EXPR_DEREF(msg->err) != ERR_INPROGRESS) {
     /* on error or immediate success, wake up the application
      * task waiting in netconn_gethostbyname */
     sys_sem_signal(API_EXPR_REF_SEM(msg->sem));
   }
+#endif /* LWIP_TCPIP_CORE_LOCKING */
 }
 #endif /* LWIP_DNS */