mount.nfs: Fix retry= to handle lack of reserved port situation

[nfs-utils.git] / support / nfs / svc_socket.c

diff --git a/support/nfs/svc_socket.c b/support/nfs/svc_socket.c
index d712cabbba387967d21275b546acafa3dc6be3f7..f44217a404821dcd059e8374531d3ac32c12d1fa 100644 (file)
--- a/support/nfs/svc_socket.c
+++ b/support/nfs/svc_socket.c
@@ -101,8 +101,6 @@ svc_socket (u_long number, int type, int protocol, int reuse)
     }
   else
     {
-      if (bindresvport (sock, &addr))
-       {
          addr.sin_port = 0;
          if (bind (sock, (struct sockaddr *) &addr, len) < 0)
            {
@@ -110,14 +108,24 @@ svc_socket (u_long number, int type, int protocol, int reuse)
              (void) __close (sock);
              sock = -1;
            }
-       }
     }
 
-  if (sock >= 0 && protocol == IPPROTO_TCP)
+  if (sock >= 0)
     {
-       /* Make the TCP rendezvous socket non-block to avoid
-        * problems with blocking in accept() after a spurious
-        * wakeup from the kernel */
+           /* This socket might be shared among multiple processes
+            * if mountd is run multi-threaded.  So it is safest to
+            * make it non-blocking, else all threads might wake
+            * one will get the data, and the others will block
+            * indefinitely.
+            * In all cases, transaction on this socket are atomic
+            * (accept for TCP, packet-read and packet-write for UDP)
+            * so O_NONBLOCK will not confuse unprepared code causing
+            * it to corrupt messages.
+            * It generally safest to have O_NONBLOCK when doing an accept
+            * as if we get a RST after the SYN and before accept runs,
+            * we can block despite being told there was an acceptable
+            * connection.
+            */
        int flags;
        if ((flags = fcntl(sock, F_GETFL)) < 0)
          {
@@ -151,7 +159,7 @@ svctcp_socket (u_long number, int reuse)
 int
 svcudp_socket (u_long number, int reuse)
 {
-  return svc_socket (number, SOCK_DGRAM, IPPROTO_UDP, reuse);
+  return svc_socket (number, SOCK_DGRAM, IPPROTO_UDP, 0);
 }
 
 #ifdef TEST