NFSD: Note an additional requirement when passing TCP sockets to portlist

User space must call listen(3) on SOCK_STREAM sockets passed into
/proc/fs/nfsd/portlist, otherwise that listener is ignored.  Document
this.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index b6a847faa0bb..d491fa9df9bd 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1061,7 +1061,9 @@ static ssize_t __write_ports(struct file *file, char *buf, size_t size)
  *                      buf:            C string containing an unsigned
  *                                      integer value representing a bound
  *                                      but unconnected socket that is to be
- *                                      used as an NFSD listener
+ *                                      used as an NFSD listener; listen(3)
+ *                                      must be called for a SOCK_STREAM
+ *                                      socket, otherwise it is ignored
  *                      size:           non-zero length of C string in @buf
  * Output:
  *      On success:     NFS service is started;