From 20b9cc37d5923949c5dd024b96a547e018232956 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=94=B0=E6=98=95?= <tianxin7@xiaomi.com>
Date: Mon, 8 Aug 2022 18:20:41 +0800
Subject: [PATCH] net/local:Make local send multi-thread safe
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: 田昕 <tianxin7@xiaomi.com>
---
 net/local/local.h         |  2 ++
 net/local/local_conn.c    | 10 ++++++++++
 net/local/local_sendmsg.c | 23 +++++++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/net/local/local.h b/net/local/local.h
index 9af3a5139d..909dfc2659 100644
--- a/net/local/local.h
+++ b/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 */
 
diff --git a/net/local/local_conn.c b/net/local/local_conn.c
index 2e343bb630..8524dded71 100644
--- a/net/local/local_conn.c
+++ b/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);
diff --git a/net/local/local_sendmsg.c b/net/local/local_sendmsg.c
index 0ad0fb6d44..92a2804d01 100644
--- a/net/local/local_sendmsg.c
+++ b/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);