diff --git a/fs/aio/aio_write.c b/fs/aio/aio_write.c
index 3f00af965c7..93bbec7a6a0 100644
--- a/fs/aio/aio_write.c
+++ b/fs/aio/aio_write.c
@@ -124,9 +124,8 @@ static void aio_write_worker(FAR void *arg)
       oflags = file_fcntl(aioc->u.aioc_filep, F_GETFL);
       if (oflags < 0)
         {
-          int errcode = get_errno();
-          ferr("ERROR: fcntl failed: %d\n", errcode);
-          aiocbp->aio_result = -errcode;
+          ferr("ERROR: file_fcntl failed: %d\n", oflags);
+          aiocbp->aio_result = oflags;
           goto errout;
         }
 
diff --git a/fs/inode/fs_files.c b/fs/inode/fs_files.c
index 1667130c932..92e93a2936a 100644
--- a/fs/inode/fs_files.c
+++ b/fs/inode/fs_files.c
@@ -190,19 +190,25 @@ void files_releaselist(FAR struct filelist *list)
  *   Assign an inode to a specific files structure.  This is the heart of
  *   dup2.
  *
+ *   Equivalent to the non-standard fs_dupfd2() function except that it
+ *   accepts struct file instances instead of file descriptors and it does
+ *   not set the errno variable.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is return on
+ *   any failure.
+ *
  ****************************************************************************/
 
 int file_dup2(FAR struct file *filep1, FAR struct file *filep2)
 {
   FAR struct filelist *list;
   FAR struct inode *inode;
-  int errcode;
   int ret;
 
   if (!filep1 || !filep1->f_inode || !filep2)
     {
-      errcode = EBADF;
-      goto errout;
+      return -EBADF;
     }
 
   list = sched_getfiles();
@@ -228,7 +234,7 @@ int file_dup2(FAR struct file *filep1, FAR struct file *filep2)
     {
       /* An error occurred while closing the driver */
 
-      goto errout_with_ret;
+      goto errout_with_sem;
     }
 
   /* Increment the reference count on the contained inode */
@@ -286,17 +292,13 @@ errout_with_inode:
   filep2->f_pos    = 0;
   filep2->f_inode  = NULL;
 
-errout_with_ret:
-  errcode              = -ret;
-
+errout_with_sem:
   if (list != NULL)
     {
       _files_semgive(list);
     }
 
-errout:
-  set_errno(errcode);
-  return ERROR;
+  return ret;
 }
 
 /****************************************************************************
diff --git a/fs/vfs/fs_close.c b/fs/vfs/fs_close.c
index 6020af57317..80dca1e04c8 100644
--- a/fs/vfs/fs_close.c
+++ b/fs/vfs/fs_close.c
@@ -102,6 +102,12 @@ int close(int fd)
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS+CONFIG_NSOCKET_DESCRIPTORS))
         {
           ret = net_close(fd);
+          if (ret < 0)
+            {
+              errcode = -ret;
+              goto errout;
+            }
+
           leave_cancellation_point();
           return ret;
         }
diff --git a/fs/vfs/fs_dup.c b/fs/vfs/fs_dup.c
index 7e8096663d9..3358e482310 100644
--- a/fs/vfs/fs_dup.c
+++ b/fs/vfs/fs_dup.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * fs/vfs/fs_dup.c
  *
- *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -69,7 +69,8 @@ int dup(int fd)
   if ((unsigned int)fd < CONFIG_NFILE_DESCRIPTORS)
     {
       /* Its a valid file descriptor.. dup the file descriptor using any
-       * other file descriptor
+       * other file descriptor.  fd_dupfd() sets the errno value in the
+       * event of any failures.
        */
 
       ret = fs_dupfd(fd, 0);
@@ -82,7 +83,7 @@ int dup(int fd)
 #if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS+CONFIG_NSOCKET_DESCRIPTORS))
         {
-          /* Yes.. dup the socket descriptor */
+          /* Yes.. dup the socket descriptor.  The errno value is not set. */
 
           ret = net_dupsd(fd, CONFIG_NFILE_DESCRIPTORS);
         }
@@ -91,7 +92,14 @@ int dup(int fd)
         {
           /* No.. then it is a bad descriptor number */
 
-          set_errno(EBADF);
+          ret = -EBADF;
+        }
+
+      /* Set the errno value on failures */
+
+      if (ret < 0)
+        {
+          set_errno(-ret);
           ret = ERROR;
         }
     }
diff --git a/fs/vfs/fs_dup2.c b/fs/vfs/fs_dup2.c
index 02ed1cbecc1..3d5d8a7b097 100644
--- a/fs/vfs/fs_dup2.c
+++ b/fs/vfs/fs_dup2.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * fs/vfs/fs_dup2.c
  *
- *   Copyright (C) 2007-2009, 2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011, 2013, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -73,25 +73,38 @@ int dup2(int fd1, int fd2)
 
   if ((unsigned int)fd1 >= CONFIG_NFILE_DESCRIPTORS)
     {
+      int ret;
+
       /* Not a valid file descriptor.  Did we get a valid socket descriptor? */
 
       if ((unsigned int)fd1 < (CONFIG_NFILE_DESCRIPTORS+CONFIG_NSOCKET_DESCRIPTORS))
         {
-          /* Yes.. dup the socket descriptor */
+          /* Yes.. dup the socket descriptor. The errno value is not set. */
 
-          return net_dupsd2(fd1, fd2);
+          ret = net_dupsd2(fd1, fd2);
         }
       else
         {
           /* No.. then it is a bad descriptor number */
 
-          set_errno(EBADF);
-          return ERROR;
+          ret = -EBADF;
         }
+
+      /* Set the errno value on failures */
+
+      if (ret < 0)
+        {
+          set_errno(-ret);
+          ret = ERROR;
+        }
+
+      return ret;
     }
   else
     {
-      /* Its a valid file descriptor.. dup the file descriptor */
+      /* Its a valid file descriptor.. dup the file descriptor.  fd_dupfd()
+       * sets the errno value in the event of any failures.
+       */
 
       return fs_dupfd2(fd1, fd2);
     }
diff --git a/fs/vfs/fs_dupfd.c b/fs/vfs/fs_dupfd.c
index 5d319641d7e..70137916d73 100644
--- a/fs/vfs/fs_dupfd.c
+++ b/fs/vfs/fs_dupfd.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * fs/vfs/fs_dupfd.c
  *
- *   Copyright (C) 2007-2009, 2011-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -68,8 +68,12 @@
  *
  * Description:
  *   Equivalent to the non-standard fs_dupfd() function except that it
- *   accepts a struct file instance instead of a file descriptor.  Currently
- *   used only by file_vfcntl();
+ *   accepts a struct file instance instead of a file descriptor and does
+ *   not set the errno variable.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned on
+ *   any failure.
  *
  ****************************************************************************/
 
@@ -81,8 +85,7 @@ int file_dup(FAR struct file *filep, int minfd)
 
   if (!DUP_ISOPEN(filep))
     {
-      set_errno(EBADF);
-      return ERROR;
+      return -EBADF;
     }
 
   /* Increment the reference count on the contained inode */
@@ -94,9 +97,8 @@ int file_dup(FAR struct file *filep, int minfd)
   fd2 = files_allocate(filep->f_inode, filep->f_oflags, filep->f_pos, minfd);
   if (fd2 < 0)
     {
-      set_errno(EMFILE);
       inode_release(filep->f_inode);
-      return ERROR;
+      return -EMFILE;
     }
 
   return fd2;
@@ -112,11 +114,17 @@ int file_dup(FAR struct file *filep, int minfd)
  *   descriptors.  If socket descriptors are not implemented, then this
  *   function IS dup().
  *
+ * Returned Value:
+ *   fs_dupfd is sometimes an OS internal function and sometimes is a direct
+ *   substitute for dup().  So it must return an errno value as though it
+ *   were dup().
+ *
  ****************************************************************************/
 
 int fs_dupfd(int fd, int minfd)
 {
   FAR struct file *filep;
+  int ret;
 
   /* Get the file structure corresponding to the file descriptor. */
 
@@ -130,7 +138,14 @@ int fs_dupfd(int fd, int minfd)
 
   /* Let file_dup() do the real work */
 
-  return file_dup(filep, minfd);
+  ret = file_dup(filep, minfd);
+  if (ret < 0)
+    {
+      set_errno(-ret);
+      return ERROR;
+    }
+
+  return OK;
 }
 
 #endif /* CONFIG_NFILE_DESCRIPTORS > 0 */
diff --git a/fs/vfs/fs_dupfd2.c b/fs/vfs/fs_dupfd2.c
index 8857c767f8d..0631553bf1b 100644
--- a/fs/vfs/fs_dupfd2.c
+++ b/fs/vfs/fs_dupfd2.c
@@ -70,6 +70,11 @@
  *   case of file descriptors.  If socket descriptors are not implemented,
  *   then this function IS dup2().
  *
+ * Returned Value:
+ *   fs_dupfd is sometimes an OS internal function and sometimes is a direct
+ *   substitute for dup2().  So it must return an errno value as though it
+ *   were dup2().
+ *
  ****************************************************************************/
 
 #if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
@@ -80,6 +85,7 @@ int dup2(int fd1, int fd2)
 {
   FAR struct file *filep1;
   FAR struct file *filep2;
+  int ret;
 
   /* Get the file structures corresponding to the file descriptors. */
 
@@ -110,7 +116,14 @@ int dup2(int fd1, int fd2)
 
   /* Perform the dup2 operation */
 
-  return file_dup2(filep1, filep2);
+  ret = file_dup2(filep1, filep2);
+  if (ret < 0)
+    {
+      set_errno(-ret);
+      return ERROR;
+    }
+
+  return OK;
 }
 
 #endif /* CONFIG_NFILE_DESCRIPTORS > 0 */
diff --git a/fs/vfs/fs_fcntl.c b/fs/vfs/fs_fcntl.c
index 4d8e74b497e..d9616a7d529 100644
--- a/fs/vfs/fs_fcntl.c
+++ b/fs/vfs/fs_fcntl.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * fs/vfs/fs_fcntl.c
  *
- *   Copyright (C) 2009, 2012-2014, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2012-2014, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -60,23 +60,30 @@
  *
  * Description:
  *   Similar to the standard vfcntl function except that is accepts a struct
- *   struct file instance instead of a file descriptor.  Currently used
- *   only by aio_fcntl();
+ *   struct file instance instead of a file descriptor.
+ *
+ * Input Parameters:
+ *   filep - Instance for struct file for the opened file.
+ *   cmd   - Indentifies the operation to be performed.
+ *   ap    - Variable argument following the command.
+ *
+ * Returned Value:
+ *   The nature of the return value depends on the command.  Non-negative
+ *   values indicate success.  Failures are reported as negated errno
+ *   values.
  *
  ****************************************************************************/
 
 #if CONFIG_NFILE_DESCRIPTORS > 0
 int file_vfcntl(FAR struct file *filep, int cmd, va_list ap)
 {
-  int errcode = 0;
-  int ret = OK;
+  int ret;
 
   /* Was this file opened ? */
 
   if (!filep->f_inode)
     {
-      errcode = EBADF;
-      goto errout;
+      return -EBADF;
     }
 
   switch (cmd)
@@ -93,6 +100,8 @@ int file_vfcntl(FAR struct file *filep, int cmd, va_list ap)
          */
 
         {
+          /* Does not set the errno variable in the event of a failure */
+
           ret = file_dup(filep, va_arg(ap, int));
         }
         break;
@@ -112,7 +121,7 @@ int file_vfcntl(FAR struct file *filep, int cmd, va_list ap)
          * successful execution of one  of  the  exec  functions.
          */
 
-        errcode = ENOSYS;
+        ret = -ENOSYS;
         break;
 
       case F_GETFL:
@@ -162,7 +171,7 @@ int file_vfcntl(FAR struct file *filep, int cmd, va_list ap)
          * fd does not refer to a socket, the results are unspecified.
          */
 
-        errcode = EBADF; /* Only valid on socket descriptors */
+        ret = -EBADF; /* Only valid on socket descriptors */
         break;
 
       case F_GETLK:
@@ -192,27 +201,35 @@ int file_vfcntl(FAR struct file *filep, int cmd, va_list ap)
          * not be done.
          */
 
-        errcode = ENOSYS; /* Not implemented */
+        ret = -ENOSYS; /* Not implemented */
         break;
 
       default:
-        errcode = EINVAL;
+        ret = -EINVAL;
         break;
     }
 
-errout:
-  if (errcode != 0)
-    {
-      set_errno(errcode);
-      return ERROR;
-    }
-
   return ret;
 }
 #endif /* CONFIG_NFILE_DESCRIPTORS > 0 */
 
 /****************************************************************************
  * Name: fcntl
+ *
+ * Description:
+ *   fcntl() will perform the operation specified by 'cmd' on an open file.
+ *
+ * Input Parameters:
+ *   fd  - File descriptor of the open file
+ *   cmd - Identifies the operation to be performed.  Command specific
+ *         arguments may follow.
+ *
+ * Returned Value:
+ *   The returned value depends on the nature of the command but for all
+ *   commands the return value of -1 (ERROR) indicates that an error has
+ *   occurred and, in this case, the errno variable will be set
+ *   appropriately
+ *
  ****************************************************************************/
 
 int fcntl(int fd, int cmd, ...)
@@ -246,7 +263,9 @@ int fcntl(int fd, int cmd, ...)
           return ERROR;
         }
 
-      /* Let file_vfcntl() do the real work */
+      /* Let file_vfcntl() do the real work.  The errno is not set on
+       * failures.
+       */
 
       ret = file_vfcntl(filep, cmd, ap);
     }
@@ -258,7 +277,9 @@ int fcntl(int fd, int cmd, ...)
 #if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS+CONFIG_NSOCKET_DESCRIPTORS))
         {
-          /* Yes.. defer socket descriptor operations to net_vfcntl() */
+          /* Yes.. defer socket descriptor operations to net_vfcntl(). The
+           * errno is not set on failures.
+           */
 
           ret = net_vfcntl(fd, cmd, ap);
         }
@@ -267,11 +288,18 @@ int fcntl(int fd, int cmd, ...)
         {
           /* No.. this descriptor number is out of range */
 
-          ret = EBADF;
+          ret = -EBADF;
         }
     }
 
   va_end(ap);
+
+  if (ret < 0)
+    {
+      set_errno(-ret);
+      ret = ERROR;
+    }
+
   leave_cancellation_point();
   return ret;
 }
diff --git a/fs/vfs/fs_ioctl.c b/fs/vfs/fs_ioctl.c
index 487643fb162..7e916b3253a 100644
--- a/fs/vfs/fs_ioctl.c
+++ b/fs/vfs/fs_ioctl.c
@@ -164,7 +164,14 @@ int ioctl(int fd, int req, unsigned long arg)
 #if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
       if ((unsigned int)fd < (CONFIG_NFILE_DESCRIPTORS+CONFIG_NSOCKET_DESCRIPTORS))
         {
-          return netdev_ioctl(fd, req, arg);
+          int ret = netdev_ioctl(fd, req, arg);
+          if (ret < 0)
+            {
+              errcode = -ret;
+              goto errout;
+            }
+
+          return ret;
         }
       else
 #endif
diff --git a/include/nuttx/fs/fs.h b/include/nuttx/fs/fs.h
index 7b3e32970f3..13a993d53e9 100644
--- a/include/nuttx/fs/fs.h
+++ b/include/nuttx/fs/fs.h
@@ -606,6 +606,14 @@ void files_releaselist(FAR struct filelist *list);
  *   Assign an inode to a specific files structure.  This is the heart of
  *   dup2.
  *
+ *   Equivalent to the non-standard fs_dupfd2() function except that it
+ *   accepts struct file instances instead of file descriptors and it does
+ *   not set the errno variable.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is return on
+ *   any failure.
+ *
  ****************************************************************************/
 
 #if CONFIG_NFILE_DESCRIPTORS > 0
@@ -625,6 +633,11 @@ int file_dup2(FAR struct file *filep1, FAR struct file *filep2);
  *   This alternative naming is used when dup could operate on both file and
  *   socket descriptors to avoid drawing unused socket support into the link.
  *
+ * Returned Value:
+ *   fs_dupfd is sometimes an OS internal function and sometimes is a direct
+ *   substitute for dup().  So it must return an errno value as though it
+ *   were dup().
+ *
  ****************************************************************************/
 
 #if CONFIG_NFILE_DESCRIPTORS > 0
@@ -639,6 +652,18 @@ int fs_dupfd(int fd, int minfd);
  *   accepts a struct file instance instead of a file descriptor.  Currently
  *   used only by file_vfcntl();
  *
+/****************************************************************************
+ * Name: file_dup
+ *
+ * Description:
+ *   Equivalent to the non-standard fs_dupfd() function except that it
+ *   accepts a struct file instance instead of a file descriptor and does
+ *   not set the errno variable.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned on
+ *   any failure.
+ *
  ****************************************************************************/
 
 int file_dup(FAR struct file *filep, int minfd);
@@ -655,6 +680,11 @@ int file_dup(FAR struct file *filep, int minfd);
  *   This alternative naming is used when dup2 could operate on both file and
  *   socket descritors to avoid drawing unused socket support into the link.
  *
+ * Returned Value:
+ *   fs_dupfd2 is sometimes an OS internal function and sometimes is a direct
+ *   substitute for dup2().  So it must return an errno value as though it
+ *   were dup2().
+ *
  ****************************************************************************/
 
 #if CONFIG_NFILE_DESCRIPTORS > 0
@@ -965,8 +995,17 @@ int file_ioctl(FAR struct file *filep, int req, unsigned long arg);
  *
  * Description:
  *   Similar to the standard vfcntl function except that is accepts a struct
- *   struct file instance instead of a file descriptor.  Currently used
- *   only by aio_fcntl();
+ *   struct file instance instead of a file descriptor.
+ *
+ * Input Parameters:
+ *   filep - Instance for struct file for the opened file.
+ *   cmd   - Indentifies the operation to be performed.
+ *   ap    - Variable argument following the command.
+ *
+ * Returned Value:
+ *   The nature of the return value depends on the command.  Non-negative
+ *   values indicate success.  Failures are reported as negated errno
+ *   values.
  *
  ****************************************************************************/
 
diff --git a/include/nuttx/net/net.h b/include/nuttx/net/net.h
index ef171edf3ac..4e35903c7e7 100644
--- a/include/nuttx/net/net.h
+++ b/include/nuttx/net/net.h
@@ -459,7 +459,8 @@ int psock_socket(int domain, int type, int protocol, FAR struct socket *psock);
  *   sockfd   Socket descriptor of socket
  *
  * Returned Value:
- *   0 on success; -1 on error with errno set appropriately.
+ *  Returns zero (OK) on success.  On failure, it returns a negated errno
+ *  value to indicate the nature of the error.
  *
  * Assumptions:
  *
@@ -477,9 +478,8 @@ int net_close(int sockfd);
  *   psock   Socket instance
  *
  * Returned Value:
- *   0 on success; -1 on error with errno set appropriately.
- *
- * Assumptions:
+ *  Returns zero (OK) on success.  On failure, it returns a negated errno
+ *  value to indicate the nature of the error.
  *
  ****************************************************************************/
 
@@ -994,8 +994,8 @@ int psock_setsockopt(FAR struct socket *psock, int level, int option,
  *   arg      The argument of the ioctl cmd
  *
  * Return:
- *   >=0 on success (positive non-zero values are cmd-specific)
- *   On a failure, -1 is returned with errno set appropriately
+ *   A non-negative value is returned on success; a negated errno value is
+ *   returned on any failure to indicate the nature of the failure:
  *
  *   EBADF
  *     'psock' is not a valid, connected socket structure.
@@ -1027,8 +1027,8 @@ int psock_ioctl(FAR struct socket *psock, int cmd, unsigned long arg);
  *   arg      The argument of the ioctl cmd
  *
  * Return:
- *   >=0 on success (positive non-zero values are cmd-specific)
- *   On a failure, -1 is returned with errno set appropriately
+ *   A non-negative value is returned on success; a negated errno value is
+ *   returned on any failure to indicate the nature of the failure:
  *
  *   EBADF
  *     'sockfd' is not a valid socket descriptor.
@@ -1103,6 +1103,10 @@ int net_poll(int sockfd, struct pollfd *fds, bool setup);
  *   of socket file descriptors.  If file descriptors are not implemented,
  *   then this function IS dup().
  *
+ * Returned Value:
+ *   On success, returns the number of characters sent.  On any error,
+ *   a negated errno value is returned:.
+ *
  ****************************************************************************/
 
 int net_dupsd(int sockfd, int minsd);
@@ -1116,6 +1120,10 @@ int net_dupsd(int sockfd, int minsd);
  *   of socket file descriptors.  If file descriptors are not implemented,
  *   then this function IS dup2().
  *
+ * Returned Value:
+ *   On success, returns the number of characters sent.  On any error,
+ *   a negated errno value is returned:.
+ *
  ****************************************************************************/
 
 int net_dupsd2(int sockfd1, int sockfd2);
@@ -1190,8 +1198,6 @@ int net_clone(FAR struct socket *psock1, FAR struct socket *psock2);
  *     In this case the process will also receive a SIGPIPE unless
  *     MSG_NOSIGNAL is set.
  *
- * Assumptions:
- *
  ****************************************************************************/
 
 #ifdef CONFIG_NET_SENDFILE
@@ -1211,8 +1217,8 @@ ssize_t net_sendfile(int outfd, struct file *infile, off_t *offset, size_t count
  *   ap     - Command-specific arguments
  *
  * Returned Value:
- *   Zero (OK) is returned on success; -1 (ERROR) is returned on failure and
- *   the errno value is set appropriately.
+ *   Zero (OK) is returned on success; a negated errno value is returned on
+ *   any failure to indicate the nature of the failure.
  *
  ****************************************************************************/
 
diff --git a/net/netdev/netdev_ioctl.c b/net/netdev/netdev_ioctl.c
index 21b00028739..b4ba8e4553d 100644
--- a/net/netdev/netdev_ioctl.c
+++ b/net/netdev/netdev_ioctl.c
@@ -1323,8 +1323,8 @@ static int netdev_rt_ioctl(FAR struct socket *psock, int cmd,
  *   arg      The argument of the ioctl cmd
  *
  * Return:
- *   >=0 on success (positive non-zero values are cmd-specific)
- *   On a failure, -1 is returned with errno set appropriately
+ *   A non-negative value is returned on success; a negated errno value is
+ *   returned on any failure to indicate the nature of the failure:
  *
  *   EBADF
  *     'psock' is not a valid, connected socket structure.
@@ -1350,8 +1350,7 @@ int psock_ioctl(FAR struct socket *psock, int cmd, unsigned long arg)
 
   if (psock == NULL || psock->s_crefs <= 0)
     {
-      ret = -EBADF;
-      goto errout;
+      return -EBADF;
     }
 
   /* Execute the command.  First check for a standard network IOCTL command. */
@@ -1419,18 +1418,7 @@ int psock_ioctl(FAR struct socket *psock, int cmd, unsigned long arg)
     }
 #endif
 
-  /* Check for success or failure */
-
-  if (ret >= 0)
-    {
-      return ret;
-    }
-
-/* On failure, set the errno and return -1 */
-
-errout:
-  set_errno(-ret);
-  return ERROR;
+  return ret;
 }
 
 /****************************************************************************
@@ -1445,8 +1433,8 @@ errout:
  *   arg      The argument of the ioctl cmd
  *
  * Return:
- *   >=0 on success (positive non-zero values are cmd-specific)
- *   On a failure, -1 is returned with errno set appropriately
+ *   A non-negative value is returned on success; a negated errno value is
+ *   returned on any failure to indicate the nature of the failure:
  *
  *   EBADF
  *     'sockfd' is not a valid socket descriptor.
diff --git a/net/socket/net_close.c b/net/socket/net_close.c
index 63cfb131b7d..1e7824c024f 100644
--- a/net/socket/net_close.c
+++ b/net/socket/net_close.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/socket/net_close.c
  *
- *   Copyright (C) 2007-2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -67,7 +67,8 @@
  *   psock   Socket instance
  *
  * Returned Value:
- *   0 on success; -1 on error with errno set appropriately.
+ *  Returns zero (OK) on success.  On failure, it returns a negated errno
+ *  value to indicate the nature of the error.
  *
  * Assumptions:
  *
@@ -75,15 +76,13 @@
 
 int psock_close(FAR struct socket *psock)
 {
-  int errcode;
   int ret;
 
   /* Verify that the sockfd corresponds to valid, allocated socket */
 
   if (!psock || psock->s_crefs <= 0)
     {
-      errcode = EBADF;
-      goto errout;
+      return -EBADF;
     }
 
   /* We perform the close operation only if this is the last count on
@@ -105,8 +104,7 @@ int psock_close(FAR struct socket *psock)
 
       if (ret < 0)
         {
-          errcode = -ret;
-          goto errout;
+          return ret;
         }
     }
 
@@ -114,10 +112,6 @@ int psock_close(FAR struct socket *psock)
 
   sock_release(psock);
   return OK;
-
-errout:
-  set_errno(errcode);
-  return ERROR;
 }
 
 /****************************************************************************
@@ -130,7 +124,8 @@ errout:
  *   sockfd   Socket descriptor of socket
  *
  * Returned Value:
- *   0 on success; -1 on error with errno set appropriately.
+ *  Returns zero (OK) on success.  On failure, it returns a negated errno
+ *  value to indicate the nature of the error.
  *
  * Assumptions:
  *
diff --git a/net/socket/net_dupsd.c b/net/socket/net_dupsd.c
index 3f92ac0252b..02e4a1da0f8 100644
--- a/net/socket/net_dupsd.c
+++ b/net/socket/net_dupsd.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/socket/net_dupsd.c
  *
- *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -61,6 +61,10 @@
  *   of socket file descriptors.  If file descriptors are not implemented,
  *   then this function IS dup().
  *
+ * Returned Value:
+ *   On success, returns the number of characters sent.  On any error,
+ *   a negated errno value is returned:.
+ *
  ****************************************************************************/
 
 int net_dupsd(int sockfd, int minsd)
@@ -68,7 +72,6 @@ int net_dupsd(int sockfd, int minsd)
   FAR struct socket *psock1;
   FAR struct socket *psock2;
   int sockfd2;
-  int errcode;
   int ret;
 
   /* Make sure that the minimum socket descriptor is within the legal range.
@@ -99,7 +102,7 @@ int net_dupsd(int sockfd, int minsd)
 
   if (!psock1 || psock1->s_crefs <= 0)
     {
-      errcode = EBADF;
+      ret = -EBADF;
       goto errout;
     }
 
@@ -108,7 +111,7 @@ int net_dupsd(int sockfd, int minsd)
   sockfd2 = sockfd_allocate(minsd);
   if (sockfd2 < 0)
     {
-      errcode = ENFILE;
+      ret = -ENFILE;
       goto errout;
     }
 
@@ -117,8 +120,8 @@ int net_dupsd(int sockfd, int minsd)
   psock2 = sockfd_socket(sockfd2);
   if (!psock2)
     {
-      errcode = ENOSYS; /* should not happen */
-      goto errout;
+      ret = -ENOSYS; /* Should not happen */
+      goto errout_with_sockfd;
     }
 
   /* Duplicate the socket state */
@@ -126,18 +129,18 @@ int net_dupsd(int sockfd, int minsd)
   ret = net_clone(psock1, psock2);
   if (ret < 0)
     {
-      errcode = -ret;
-      goto errout;
-
+      goto errout_with_sockfd;
     }
 
   sched_unlock();
   return sockfd2;
 
+errout_with_sockfd:
+  sockfd_release(sockfd2);
+
 errout:
   sched_unlock();
-  set_errno(errcode);
-  return ERROR;
+  return ret;
 }
 
 #endif /* defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0 */
diff --git a/net/socket/net_dupsd2.c b/net/socket/net_dupsd2.c
index 4d6027667cc..dbd3980f435 100644
--- a/net/socket/net_dupsd2.c
+++ b/net/socket/net_dupsd2.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/socket/net_dupsd2.c
  *
- *   Copyright (C) 2009, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2011, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -44,6 +44,8 @@
 #include <errno.h>
 #include <debug.h>
 
+#include <nuttx/net/net.h>
+
 #include "socket/socket.h"
 
 #if defined(CONFIG_NET) && CONFIG_NSOCKET_DESCRIPTORS > 0
@@ -61,6 +63,10 @@
  *   of socket file descriptors.  If file descriptors are not implemented,
  *   then this function IS dup2().
  *
+ * Returned Value:
+ *   On success, returns the number of characters sent.  On any error,
+ *   a negated errno value is returned:.
+ *
  ****************************************************************************/
 
 #if CONFIG_NFILE_DESCRIPTORS > 0
@@ -71,7 +77,6 @@ int dup2(int sockfd1, int sockfd2)
 {
   FAR struct socket *psock1;
   FAR struct socket *psock2;
-  int errcode;
   int ret;
 
   /* Lock the scheduler throughout the following */
@@ -89,7 +94,7 @@ int dup2(int sockfd1, int sockfd2)
 
   if (!psock1 || !psock2 || psock1->s_crefs <= 0)
     {
-      errcode = EBADF;
+      ret = -EBADF;
       goto errout;
     }
 
@@ -105,19 +110,10 @@ int dup2(int sockfd1, int sockfd2)
   /* Duplicate the socket state */
 
   ret = net_clone(psock1, psock2);
-  if (ret < 0)
-    {
-      errcode = -ret;
-      goto errout;
-    }
-
-  sched_unlock();
-  return OK;
 
 errout:
   sched_unlock();
-  set_errno(errcode);
-  return ERROR;
+  return ret;
 }
 
 #endif /* CONFIG_NET && CONFIG_NSOCKET_DESCRIPTORS > 0 */
diff --git a/net/socket/net_sendfile.c b/net/socket/net_sendfile.c
index 6348df24a72..8fd78133592 100644
--- a/net/socket/net_sendfile.c
+++ b/net/socket/net_sendfile.c
@@ -115,8 +115,6 @@
  *     In this case the process will also receive a SIGPIPE unless
  *     MSG_NOSIGNAL is set.
  *
- * Assumptions:
- *
  ****************************************************************************/
 
 ssize_t net_sendfile(int outfd, FAR struct file *infile, FAR off_t *offset,
diff --git a/net/socket/net_vfcntl.c b/net/socket/net_vfcntl.c
index 54e5c8ac4af..20cd63e0125 100644
--- a/net/socket/net_vfcntl.c
+++ b/net/socket/net_vfcntl.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/socket/net_vfcntl.c
  *
- *   Copyright (C) 2009, 2012-2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2012-2015, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -70,16 +70,15 @@
  *   ap     - Command-specific arguments
  *
  * Returned Value:
- *   Zero (OK) is returned on success; -1 (ERROR) is returned on failure and
- *   the errno value is set appropriately.
+ *   Zero (OK) is returned on success; a negated errno value is returned on
+ *   any failure to indicate the nature of the failure.
  *
  ****************************************************************************/
 
 int net_vfcntl(int sockfd, int cmd, va_list ap)
 {
   FAR struct socket *psock = sockfd_socket(sockfd);
-  int errcode = 0;
-  int ret = 0;
+  int ret;
 
   ninfo("sockfd=%d cmd=%d\n", sockfd, cmd);
 
@@ -87,8 +86,7 @@ int net_vfcntl(int sockfd, int cmd, va_list ap)
 
   if (psock == NULL || psock->s_crefs <= 0)
     {
-      errcode = EBADF;
-      goto errout;
+      return -EBADF;
     }
 
   /* Interrupts must be disabled in order to perform operations on socket structures */
@@ -108,6 +106,8 @@ int net_vfcntl(int sockfd, int cmd, va_list ap)
          */
 
         {
+          /* Does not set the errno value on failure */
+
           ret = net_dupsd(sockfd, va_arg(ap, int));
         }
         break;
@@ -127,7 +127,7 @@ int net_vfcntl(int sockfd, int cmd, va_list ap)
          * successful execution of one  of  the  exec  functions.
          */
 
-         errcode = ENOSYS; /* F_GETFD and F_SETFD not implemented */
+         ret = -ENOSYS; /* F_GETFD and F_SETFD not implemented */
          break;
 
       case F_GETFL:
@@ -245,25 +245,16 @@ int net_vfcntl(int sockfd, int cmd, va_list ap)
          * not be done.
          */
 
-         errcode = ENOSYS; /* F_GETOWN, F_SETOWN, F_GETLK, F_SETLK, F_SETLKW */
+         ret = -ENOSYS; /* F_GETOWN, F_SETOWN, F_GETLK, F_SETLK, F_SETLKW */
          break;
 
       default:
-         errcode = EINVAL;
+         ret = -EINVAL;
          break;
-  }
-
-  net_unlock();
-
-errout:
-  if (errcode != 0)
-    {
-      set_errno(errcode);
-      return ERROR;
     }
 
+  net_unlock();
   return ret;
 }
 
 #endif /* CONFIG_NET && CONFIG_NSOCKET_DESCRIPTORS > 0 */
-
diff --git a/net/socket/socket.h b/net/socket/socket.h
index f90cf85a354..b03d0ccbf46 100644
--- a/net/socket/socket.h
+++ b/net/socket/socket.h
@@ -231,42 +231,6 @@ FAR struct socket *sockfd_socket(int sockfd);
 
 FAR const struct sock_intf_s *net_sockif(sa_family_t family);
 
-/****************************************************************************
- * Name: psock_close
- *
- * Description:
- *   Performs the close operation on a socket instance
- *
- * Parameters:
- *   psock   Socket instance
- *
- * Returned Value:
- *   0 on success; -1 on error with errno set appropriately.
- *
- * Assumptions:
- *
- ****************************************************************************/
-
-int psock_close(FAR struct socket *psock);
-
-/****************************************************************************
- * Name: net_close
- *
- * Description:
- *   Performs the close operation on socket descriptors
- *
- * Parameters:
- *   sockfd   Socket descriptor of socket
- *
- * Returned Value:
- *   0 on success; -1 on error with errno set appropriately.
- *
- * Assumptions:
- *
- ****************************************************************************/
-
-int net_close(int sockfd);
-
 /****************************************************************************
  * Name: net_timeo
  *