Networking: Fixes another CONFIG_NET_NOINTS issues. When called sem_timedwait() with the network locked, the network stays logcked while we wait which is not what we want (without CONFIG_NET_NOINTS, interrupts are re-enabled while we wait and all is well).

net/arp/arp.h

@@ -345,8 +345,8 @@ int arp_wait_cancel(FAR struct arp_notify_s *notify);
  *   timeout occurs.
  *
  * Assumptions:
- *   This function is called from ARP send and executes in the normal
- *   tasking environment.
+ *   This function is called from ARP send and mut execute with the network
+ *   un-locked.
  *
  ****************************************************************************/
 
@@ -366,7 +366,7 @@ int arp_wait(FAR struct arp_notify_s *notify, FAR struct timespec *timeout);
  *
  * Assumptions:
  *   This function is called from the MAC device driver indirectly through
- *   arp_arpin() and may be execute from the interrupt level.
+ *   arp_arpin() and will execute with the network locked.
  *
  ****************************************************************************/
 

net/arp/arp_notify.c

@@ -166,8 +166,8 @@ int arp_wait_cancel(FAR struct arp_notify_s *notify)
  *   timeout occurs.
  *
  * Assumptions:
- *   This function is called from ARP send and executes in the normal
- *   tasking environment.
+ *   This function is called from ARP send must execute with the network
+ *   un-locked (interrupts may be disabled to keep the things stable).
  *
  ****************************************************************************/
 
@@ -220,7 +220,7 @@ int arp_wait(FAR struct arp_notify_s *notify, FAR struct timespec *timeout)
  *
  * Assumptions:
  *   This function is called from the MAC device driver indirectly through
- *   arp_arpin() and may be execute from the interrupt level.
+ *   arp_arpin() will execute with the network locked.
  *
  ****************************************************************************/
 

net/arp/arp_send.c

@@ -190,6 +190,9 @@ int arp_send(in_addr_t ipaddr)
   struct arp_notify_s notify;
   struct timespec delay;
   struct arp_send_s state;
+#ifdef CONFIG_NET_NOINTS
+  irqstate_t flags;
+#endif
   net_lock_t save;
   int ret;
 
@@ -358,12 +361,21 @@ int arp_send(in_addr_t ipaddr)
 
       /* Now wait for response to the ARP response to be received.  The
        * optimal delay would be the work case round trip time.
+       * NOTE: The network is locked.
        */
 
       delay.tv_sec  = CONFIG_ARP_SEND_DELAYSEC;
       delay.tv_nsec = CONFIG_ARP_SEND_DELAYNSEC;
 
+#ifdef CONFIG_NET_NOINTS
+      flags = irqsave();  /* Keep things stable */
+      net_unlock(save);   /* Unlock the network with interrupts disabled */
+#endif
       ret = arp_wait(&notify, &delay);
+#ifdef CONFIG_NET_NOINTS
+      save = net_lock();  /* Re-lock the network with interrupts disabled */
+      irqrestore(flags);
+#endif
 
       /* arp_wait will return OK if and only if the matching ARP response
        * is received.  Otherwise, it will return -ETIMEDOUT.