um: switch line.c tty drivers to dynamic device creation

Current code doesn't update the symlinks in /sys/dev/char when we add/remove
tty lines.  Fixing that allows to stop messing with ->valid before the driver
registration, which is a Good Thing(tm) - we shouldn't have it set before we
really have the things set up and ready for line_open().

We need tty_driver available to call tty_{un,}register_device(), so we just
stash a reference to it into struct line_driver.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 5 insertions, 4 deletions

diff --git a/arch/um/drivers/line.h b/arch/um/drivers/line.h
index 471f477b271e..e3f86065e049 100644
--- a/arch/um/drivers/line.h
+++ b/arch/um/drivers/line.h
@@ -15,7 +15,7 @@
 #include "chan_user.h"
 #include "mconsole_kern.h"
 
-/* There's only one modifiable field in this - .mc.list */
+/* There's only two modifiable fields in this - .mc.list and .driver */
 struct line_driver {
         const char *name;
         const char *device_name;
@@ -28,6 +28,7 @@ struct line_driver {
         const int write_irq;
         const char *write_irq_name;
         struct mc_device mc;
+        struct tty_driver *driver;
 };
 
 struct line {
@@ -78,9 +79,9 @@ extern char *add_xterm_umid(char *base);
 extern int line_setup_irq(int fd, int input, int output, struct line *line,
                           void *data);
 extern void line_close_chan(struct line *line);
-extern struct tty_driver *register_lines(struct line_driver *line_driver,
-                                         const struct tty_operations *driver,
-                                         struct line *lines, int nlines);
+extern int register_lines(struct line_driver *line_driver,
+                          const struct tty_operations *driver,
+                          struct line *lines, int nlines);
 extern void lines_init(struct line *lines, int nlines, struct chan_opts *opts);
 extern void close_lines(struct line *lines, int nlines);