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, 19 insertions, 4 deletions

diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index 3aa351611763..368d3e97dfd9 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -203,22 +203,37 @@ void chan_enable_winch(struct list_head *chans, struct tty_struct *tty)
         }
 }
 
-void enable_chan(struct line *line)
+int enable_chan(struct line *line)
 {
         struct list_head *ele;
         struct chan *chan;
+        int err;
 
         list_for_each(ele, &line->chan_list){
                 chan = list_entry(ele, struct chan, list);
-                if(open_one_chan(chan))
+                err = open_one_chan(chan);
+                if (err) {
+                        if (chan->primary)
+                                goto out_close;
+
                         continue;
+                }
 
                 if(chan->enabled)
                         continue;
-                line_setup_irq(chan->fd, chan->input, chan->output, line,
-                               chan);
+                err = line_setup_irq(chan->fd, chan->input, chan->output, line,
+                                     chan);
+                if (err)
+                        goto out_close;
+
                 chan->enabled = 1;
         }
+
+        return 0;
+
+ out_close:
+        close_chan(&line->chan_list, 0);
+        return err;
 }
 
 /* Items are added in IRQ context, when free_irq can't be called, and