net: Fix task block when devif_send fails.

When a task needs to send data, a callback is allocated and the
transmission is happening in a worker task through devif_send.
Synchronization between the two tasks (sender & worker) is
achieved by a semaphore.

If devif_send fails, this semaphore was never posted, leaving
the sending task blocked indefinitely. This commit fixes this
by checking the return code of netif_send, and posting this
semaphore in case of failure.

Polling then stops, and execution is resumed on the sending
task.

net/can/can_sendmsg.c

@@ -106,11 +106,13 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
         {
           /* Copy the packet data into the device packet buffer and send it */
 
-          devif_send(dev, pstate->snd_buffer, pstate->snd_buflen, 0);
+          int ret = devif_send(dev, pstate->snd_buffer,
+                               pstate->snd_buflen, 0);
           dev->d_len = dev->d_sndlen;
-          if (dev->d_sndlen == 0)
+          if (ret <= 0)
             {
-              return flags;
+              pstate->snd_sent = ret;
+              goto end_wait;
             }
 
           pstate->snd_sent = pstate->snd_buflen;
@@ -122,6 +124,8 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
             }
         }
 
+end_wait:
+
       /* Don't allow any further call backs. */
 
       pstate->snd_cb->flags = 0;

net/devif/devif.h

@@ -432,31 +432,40 @@ uint16_t devif_conn_event(FAR struct net_driver_s *dev, uint16_t flags,
 uint16_t devif_dev_event(FAR struct net_driver_s *dev, uint16_t flags);
 
 /****************************************************************************
- * Send data on the current connection.
+ * Name: devif_send
  *
- * This function is used to send out a single segment of TCP data.  Only
- * socket logic that have been invoked by the lower level for event
- * processing can send data.
+ * Description:
+ *   Send data on the current connection.
+ *
+ *   This function is used to send out a single segment of TCP data.  Only
+ *   socket logic that have been invoked by the lower level for event
+ *   processing can send data.
  *
- * The amount of data that actually is sent out after a call to this
- * function is determined by the maximum amount of data TCP allows. The
- * network will automatically crop the data so that only the appropriate
- * amount of data is sent. The mss field of the TCP connection structure
- * can be used to determine the amount of data that actually will be sent.
+ *   The amount of data that actually is sent out after a call to this
+ *   function is determined by the maximum amount of data TCP allows. The
+ *   network will automatically crop the data so that only the appropriate
+ *   amount of data is sent. The mss field of the TCP connection structure
+ *   can be used to determine the amount of data that actually will be sent.
  *
  * Note:  This function does not guarantee that the sent data will
  * arrive at the destination.  If the data is lost in the network, the
  * TCP socket layer will be invoked with the TCP_REXMIT flag set.  The
  * socket layer will then have to resend the data using this function.
  *
- * data A pointer to the data which is to be sent.
+ * Input Parameters:
+ *   dev - The network device state structure associated with the network
+ *     device that initiated the callback event.
+ *   buf - A pointer to the data which is to be sent.
+ *   len - The maximum amount of data bytes to be sent.
+ *   offset - Offset of data in buffer.
  *
- * len The maximum amount of data bytes to be sent.
+ * Returned Value:
+ *   The amount of data sent, or negated ERRNO in case of failure.
  *
  ****************************************************************************/
 
-void devif_send(FAR struct net_driver_s *dev, FAR const void *buf,
-                int len, unsigned int offset);
+int devif_send(FAR struct net_driver_s *dev, FAR const void *buf,
+               int len, unsigned int offset);
 
 /****************************************************************************
  * Name: devif_iob_send
@@ -475,9 +484,9 @@ void devif_send(FAR struct net_driver_s *dev, FAR const void *buf,
 
 #ifdef CONFIG_MM_IOB
 struct iob_s;
-void devif_iob_send(FAR struct net_driver_s *dev, FAR struct iob_s *buf,
-                    unsigned int len, unsigned int offset,
-                    unsigned int target_offset);
+int devif_iob_send(FAR struct net_driver_s *dev, FAR struct iob_s *buf,
+                   unsigned int len, unsigned int offset,
+                   unsigned int target_offset);
 #endif
 
 /****************************************************************************

net/devif/devif_iobsend.c

@@ -53,9 +53,9 @@
  *
  ****************************************************************************/
 
-void devif_iob_send(FAR struct net_driver_s *dev, FAR struct iob_s *iob,
-                    unsigned int len, unsigned int offset,
-                    unsigned int target_offset)
+int devif_iob_send(FAR struct net_driver_s *dev, FAR struct iob_s *iob,
+                   unsigned int len, unsigned int offset,
+                   unsigned int target_offset)
 {
   int ret;
 
@@ -105,10 +105,11 @@ void devif_iob_send(FAR struct net_driver_s *dev, FAR struct iob_s *iob,
   lib_dumpbuffer("devif_iob_send", dev->d_appdata, len);
 #endif
 
-  return;
+  return dev->d_sndlen;
 
 errout:
   nerr("ERROR: devif_iob_send error: %d\n", ret);
+  return ret;
 }
 
 #endif /* CONFIG_MM_IOB */

net/devif/devif_send.c

@@ -66,8 +66,8 @@
  *
  ****************************************************************************/
 
-void devif_send(FAR struct net_driver_s *dev, FAR const void *buf,
-                int len, unsigned int offset)
+int devif_send(FAR struct net_driver_s *dev, FAR const void *buf,
+               int len, unsigned int offset)
 {
   int ret;
 
@@ -113,8 +113,9 @@ void devif_send(FAR struct net_driver_s *dev, FAR const void *buf,
 
   dev->d_sndlen = len;
 
-  return;
+  return dev->d_sndlen;
 
 errout:
   nerr("ERROR: devif_send error: %d\n", ret);
+  return ret;
 }

net/pkt/pkt_sendmsg.c

@@ -105,10 +105,12 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
         {
           /* Copy the packet data into the device packet buffer and send it */
 
-          devif_send(dev, pstate->snd_buffer, pstate->snd_buflen, 0);
-          if (dev->d_sndlen == 0)
+          int ret = devif_send(dev, pstate->snd_buffer,
+                               pstate->snd_buflen, 0);
+          if (ret <= 0)
             {
-              return flags;
+              pstate->snd_sent = ret;
+              goto end_wait;
             }
 
           pstate->snd_sent = pstate->snd_buflen;
@@ -120,6 +122,8 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
           IFF_SET_NOARP(dev->d_flags);
         }
 
+end_wait:
+
       /* Don't allow any further call backs. */
 
       pstate->snd_cb->flags    = 0;

net/tcp/tcp_send_buffered.c

@@ -695,6 +695,7 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
       FAR sq_entry_t *entry;
       FAR sq_entry_t *next;
       size_t sndlen;
+      int ret;
 
       /* According to RFC 6298 (5.4), retransmit the earliest segment
        * that has not been acknowledged by the TCP receiver.
@@ -742,9 +743,9 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
 
           tcp_setsequence(conn->sndseq, TCP_WBSEQNO(wrb));
 
-          devif_iob_send(dev, TCP_WBIOB(wrb), sndlen,
-                         0, tcpip_hdrsize(conn));
-          if (dev->d_sndlen == 0)
+          ret = devif_iob_send(dev, TCP_WBIOB(wrb), sndlen,
+                               0, tcpip_hdrsize(conn));
+          if (ret <= 0)
             {
               return flags;
             }
@@ -1005,6 +1006,7 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
       if (TCP_SEQ_LT(seq, snd_wnd_edge))
         {
           uint32_t remaining_snd_wnd;
+          int ret;
 
           sndlen = TCP_WBPKTLEN(wrb) - TCP_WBSENT(wrb);
           if (sndlen > conn->mss)
@@ -1048,9 +1050,9 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
            * won't actually happen until the polling cycle completes).
            */
 
-          devif_iob_send(dev, TCP_WBIOB(wrb), sndlen,
-                         TCP_WBSENT(wrb), tcpip_hdrsize(conn));
-          if (dev->d_sndlen == 0)
+          ret = devif_iob_send(dev, TCP_WBIOB(wrb), sndlen,
+                               TCP_WBSENT(wrb), tcpip_hdrsize(conn));
+          if (ret <= 0)
             {
               return flags;
             }

net/tcp/tcp_send_unbuffered.c

@@ -126,6 +126,7 @@ static uint16_t tcpsend_eventhandler(FAR struct net_driver_s *dev,
 {
   FAR struct send_s *pstate = pvpriv;
   FAR struct tcp_conn_s *conn;
+  int ret;
 
   DEBUGASSERT(pstate != NULL);
 
@@ -283,8 +284,12 @@ static uint16_t tcpsend_eventhandler(FAR struct net_driver_s *dev,
        * happen until the polling cycle completes).
        */
 
-      devif_send(dev, &pstate->snd_buffer[pstate->snd_acked],
-                 sndlen, tcpip_hdrsize(conn));
+      ret = devif_send(dev, &pstate->snd_buffer[pstate->snd_acked],
+                       sndlen, tcpip_hdrsize(conn));
+      if (ret <= 0)
+        {
+          goto end_wait;
+        }
 
       /* Continue waiting */
 
@@ -365,11 +370,11 @@ static uint16_t tcpsend_eventhandler(FAR struct net_driver_s *dev,
            * happen until the polling cycle completes).
            */
 
-          devif_send(dev, &pstate->snd_buffer[pstate->snd_sent],
-                     sndlen, tcpip_hdrsize(conn));
-          if (dev->d_sndlen == 0)
+          ret = devif_send(dev, &pstate->snd_buffer[pstate->snd_sent],
+                           sndlen, tcpip_hdrsize(conn));
+          if (ret <= 0)
             {
-              return flags;
+              goto end_wait;
             }
 
           /* Update the amount of data sent (but not necessarily ACKed) */

net/udp/udp_sendto_unbuffered.c

@@ -194,11 +194,12 @@ static uint16_t sendto_eventhandler(FAR struct net_driver_s *dev,
         {
           /* Copy the user data into d_appdata and send it */
 
-          devif_send(dev, pstate->st_buffer,
-                     pstate->st_buflen, udpip_hdrsize(pstate->st_conn));
-          if (dev->d_sndlen == 0)
+          int ret = devif_send(dev, pstate->st_buffer, pstate->st_buflen,
+                               udpip_hdrsize(pstate->st_conn));
+          if (ret <= 0)
             {
-              return flags;
+              pstate->st_sndlen = ret;
+              goto end_wait;
             }
 
 #ifdef NEED_IPDOMAIN_SUPPORT
@@ -214,6 +215,8 @@ static uint16_t sendto_eventhandler(FAR struct net_driver_s *dev,
           pstate->st_sndlen = pstate->st_buflen;
         }
 
+end_wait:
+
       /* Don't allow any further call backs. */
 
       pstate->st_cb->flags = 0;