From 9dca4a02115ee0567f8b539ea97a4f2e197b770a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joan=20Lled=C3=B3?= <jlledom@member.fsf.org>
Date: Sun, 19 May 2019 11:08:45 +0200
Subject: [PATCH] New function tcpip_callback_wait() * Call a function inside
 the tcpip thread and block the calling thread until the callback finishes.

Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>
---
 src/api/tcpip.c                    | 48 ++++++++++++++++++++++++++++++
 src/include/lwip/priv/tcpip_priv.h |  8 ++++-
 src/include/lwip/tcpip.h           |  1 +
 3 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/src/api/tcpip.c b/src/api/tcpip.c
index b0382e83..fc25df9c 100644
--- a/src/api/tcpip.c
+++ b/src/api/tcpip.c
@@ -166,6 +166,11 @@ tcpip_thread_handle_msg(struct tcpip_msg *msg)
       msg->msg.api_call.arg->err = msg->msg.api_call.function(msg->msg.api_call.arg);
       sys_sem_signal(msg->msg.api_call.sem);
       break;
+    case TCPIP_MSG_CALLBACK_STATIC_WAIT:
+      LWIP_DEBUGF(TCPIP_DEBUG, ("tcpip_thread: CALLBACK WAIT message %p\n", (void *)msg));
+      msg->msg.cb_wait.function(msg->msg.cb_wait.ctx);
+      sys_sem_signal(msg->msg.cb_wait.sem);
+      break;
 #endif /* !LWIP_TCPIP_CORE_LOCKING */
 
 #if !LWIP_TCPIP_CORE_LOCKING_INPUT
@@ -589,6 +594,49 @@ tcpip_callbackmsg_trycallback_fromisr(struct tcpip_callback_msg *msg)
   return sys_mbox_trypost_fromisr(&tcpip_mbox, msg);
 }
 
+/**
+ * Sends a message to TCPIP thread to call a function. Caller thread blocks
+ * until the function returns.
+ * It is recommended to use LWIP_TCPIP_CORE_LOCKING (preferred) or
+ * LWIP_NETCONN_SEM_PER_THREAD.
+ * If not, a semaphore is created and destroyed on every call which is usually
+ * an expensive/slow operation.
+ *
+ * @param function the function to call
+ * @param ctx parameter passed to f
+ * @return ERR_OK if the function was called, another err_t if not
+ */
+err_t
+tcpip_callback_wait(tcpip_callback_fn function, void *ctx)
+{
+#if LWIP_TCPIP_CORE_LOCKING
+  LOCK_TCPIP_CORE();
+  function(ctx);
+  UNLOCK_TCPIP_CORE();
+  return ERR_OK;
+#else /* LWIP_TCPIP_CORE_LOCKING */
+  err_t err;
+  sys_sem_t sem;
+  struct tcpip_msg msg;
+
+  LWIP_ASSERT("Invalid mbox", sys_mbox_valid_val(tcpip_mbox));
+
+  err = sys_sem_new(&sem, 0);
+  if (err != ERR_OK) {
+    return err;
+  }
+
+  msg.type = TCPIP_MSG_CALLBACK_STATIC_WAIT;
+  msg.msg.cb_wait.function = function;
+  msg.msg.cb_wait.ctx = ctx;
+  msg.msg.cb_wait.sem = &sem;
+  sys_mbox_post(&tcpip_mbox, &msg);
+  sys_arch_sem_wait(&sem, 0);
+  sys_sem_free(&sem);
+  return ERR_OK;
+#endif /* LWIP_TCPIP_CORE_LOCKING */
+}
+
 /**
  * @ingroup lwip_os
  * Initialize this module:
diff --git a/src/include/lwip/priv/tcpip_priv.h b/src/include/lwip/priv/tcpip_priv.h
index 74be634b..bfa88ff6 100644
--- a/src/include/lwip/priv/tcpip_priv.h
+++ b/src/include/lwip/priv/tcpip_priv.h
@@ -123,7 +123,8 @@ enum tcpip_msg_type {
   TCPIP_MSG_UNTIMEOUT,
 #endif /* LWIP_TCPIP_TIMEOUT && LWIP_TIMERS */
   TCPIP_MSG_CALLBACK,
-  TCPIP_MSG_CALLBACK_STATIC
+  TCPIP_MSG_CALLBACK_STATIC,
+  TCPIP_MSG_CALLBACK_STATIC_WAIT
 };
 
 struct tcpip_msg {
@@ -139,6 +140,11 @@ struct tcpip_msg {
       struct tcpip_api_call_data *arg;
       sys_sem_t *sem;
     } api_call;
+    struct {
+      tcpip_callback_fn function;
+      void *ctx;
+      sys_sem_t *sem;
+    } cb_wait;
 #endif /* LWIP_TCPIP_CORE_LOCKING */
 #if !LWIP_TCPIP_CORE_LOCKING_INPUT
     struct {
diff --git a/src/include/lwip/tcpip.h b/src/include/lwip/tcpip.h
index 0b8880a9..30ce4fef 100644
--- a/src/include/lwip/tcpip.h
+++ b/src/include/lwip/tcpip.h
@@ -81,6 +81,7 @@ err_t  tcpip_input(struct pbuf *p, struct netif *inp);
 
 err_t  tcpip_try_callback(tcpip_callback_fn function, void *ctx);
 err_t  tcpip_callback(tcpip_callback_fn function, void *ctx);
+err_t  tcpip_callback_wait(tcpip_callback_fn function, void *ctx);
 /**  @ingroup lwip_os
  * @deprecated use tcpip_try_callback() or tcpip_callback() instead
  */