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>

4 files changed, 36 insertions, 7 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
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 4bd40bb43ec2..1fb3e51108b9 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -454,7 +454,10 @@ int line_open(struct line *lines, struct tty_struct *tty)
         tty->driver_data = line;
         line->tty = tty;
 
-        enable_chan(line);
+        err = enable_chan(line);
+        if (err)
+                return err;
+
         INIT_DELAYED_WORK(&line->task, line_timer_cb);
 
         if(!line->sigio){
diff --git a/arch/um/drivers/ssl.c b/arch/um/drivers/ssl.c
index b4ecf8db8f09..875d60d0c6a2 100644
--- a/arch/um/drivers/ssl.c
+++ b/arch/um/drivers/ssl.c
@@ -97,7 +97,13 @@ static int ssl_remove(int n, char **error_out)
 
 static int ssl_open(struct tty_struct *tty, struct file *filp)
 {
-        return line_open(serial_lines, tty);
+        int err = line_open(serial_lines, tty);
+
+        if (err)
+                printk(KERN_ERR "Failed to open serial line %d, err = %d\n",
+                       tty->index, err);
+
+        return err;
 }
 
 #if 0
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 */