uml: handle errors on opening host side of consoles

If the host side of a console can't be opened, this will now produce visible
error messages.

enable_chan now returns a status and this is passed up to con_open and
ssl_open, which will complain if anything went wrong.

The default host device for the serial line driver is now a pts device rather
than a pty device since lots of hosts have LEGACY_PTYS disabled.  This had
always been failing on such hosts, but silently.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/arch/um/drivers/stdio_console.c b/arch/um/drivers/stdio_console.c
index e312488a7a99..656036e90b19 100644
--- a/arch/um/drivers/stdio_console.c
+++ b/arch/um/drivers/stdio_console.c
@@ -99,7 +99,12 @@ static int con_remove(int n, char **error_out)
 
 static int con_open(struct tty_struct *tty, struct file *filp)
 {
-        return line_open(vts, tty);
+        int err = line_open(vts, tty);
+        if (err)
+                printk(KERN_ERR "Failed to open console %d, err = %d\n",
+                       tty->index, err);
+
+        return err;
 }
 
 /* Set in an initcall, checked in an exitcall */