net/local:Make local send multi-thread safe

Signed-off-by: 田昕 <tianxin7@xiaomi.com>

net/local/local.h

@@ -141,6 +141,8 @@ struct local_conn_s
      lc_cfps[LOCAL_NCONTROLFDS]; /* Socket message control filep */
 #endif /* CONFIG_NET_LOCAL_SCM */
 
+  sem_t lc_sendsem;            /* Make sending multi-thread safe */
+
 #ifdef CONFIG_NET_LOCAL_STREAM
   /* SOCK_STREAM fields common to both client and server */
 

net/local/local_conn.c

@@ -130,6 +130,12 @@ FAR struct local_conn_s *local_alloc(void)
 
 #endif
 
+      /* This semaphore is used for sending safely in multithread.
+       * Make sure data will not be garbled when multi-thread sends.
+       */
+
+      nxsem_init(&conn->lc_sendsem, 0, 1);
+
       /* Add the connection structure to the list of listeners */
 
       net_lock();
@@ -210,6 +216,10 @@ void local_free(FAR struct local_conn_s *conn)
   nxsem_destroy(&conn->lc_donesem);
 #endif
 
+  /* Destory sem associated with the connection */
+
+  nxsem_destroy(&conn->lc_sendsem);
+
   /* And free the connection structure */
 
   kmm_free(conn);

net/local/local_sendmsg.c

@@ -196,7 +196,16 @@ static ssize_t local_send(FAR struct socket *psock,
 
           /* Send the packet */
 
+          ret = nxsem_wait_uninterruptible(&peer->lc_sendsem);
+          if (ret < 0)
+            {
+              /* May fail because the task was canceled. */
+
+              return ret;
+            }
+
           ret = local_send_packet(&peer->lc_outfile, buf, len, false);
+          nxsem_post(&peer->lc_sendsem);
         }
         break;
 #endif /* CONFIG_NET_LOCAL_STREAM */
@@ -334,6 +343,16 @@ static ssize_t local_sendto(FAR struct socket *psock,
       goto errout_with_halfduplex;
     }
 
+  /* Make sure that dgram is sent safely */
+
+  ret = nxsem_wait_uninterruptible(&conn->lc_sendsem);
+  if (ret < 0)
+    {
+      /* May fail because the task was canceled. */
+
+      goto errout_with_sender;
+    }
+
   /* Send the packet */
 
   ret = local_send_packet(&conn->lc_outfile, buf, len, true);
@@ -342,6 +361,10 @@ static ssize_t local_sendto(FAR struct socket *psock,
       nerr("ERROR: Failed to send the packet: %zd\n", ret);
     }
 
+  nxsem_post(&conn->lc_sendsem);
+
+errout_with_sender:
+
   /* Now we can close the write-only socket descriptor */
 
   file_close(&conn->lc_outfile);