TTY: pdc_cons, fix open vs pdc_console_tty_driver race

Assign the pointer to pdc_console_tty_driver (a tty_driver) earlier.
Otherwise the timer may dereference NULL.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 13 insertions, 16 deletions

diff --git a/arch/parisc/kernel/pdc_cons.c b/arch/parisc/kernel/pdc_cons.c
index 8ad05215d4b..d14e20fc60d 100644
--- a/arch/parisc/kernel/pdc_cons.c
+++ b/arch/parisc/kernel/pdc_cons.c
@@ -160,9 +160,7 @@ static void pdc_console_poll(unsigned long unused)
 
 static int __init pdc_console_tty_driver_init(void)
 {
-
         int err;
-        struct tty_driver *drv;
 
         /* Check if the console driver is still registered.
          * It is unregistered if the pdc console was not selected as the
@@ -184,28 +182,27 @@ static int __init pdc_console_tty_driver_init(void)
         printk(KERN_INFO "The PDC console driver is still registered, removing CON_BOOT flag\n");
         pdc_cons.flags &= ~CON_BOOT;
 
-        drv = alloc_tty_driver(1);
+        pdc_console_tty_driver = alloc_tty_driver(1);
 
-        if (!drv)
+        if (!pdc_console_tty_driver)
                 return -ENOMEM;
 
-        drv->driver_name = "pdc_cons";
-        drv->name = "ttyB";
-        drv->major = MUX_MAJOR;
-        drv->minor_start = 0;
-        drv->type = TTY_DRIVER_TYPE_SYSTEM;
-        drv->init_termios = tty_std_termios;
-        drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
-        tty_set_operations(drv, &pdc_console_tty_ops);
-
-        err = tty_register_driver(drv);
+        pdc_console_tty_driver->driver_name = "pdc_cons";
+        pdc_console_tty_driver->name = "ttyB";
+        pdc_console_tty_driver->major = MUX_MAJOR;
+        pdc_console_tty_driver->minor_start = 0;
+        pdc_console_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
+        pdc_console_tty_driver->init_termios = tty_std_termios;
+        pdc_console_tty_driver->flags = TTY_DRIVER_REAL_RAW |
+                TTY_DRIVER_RESET_TERMIOS;
+        tty_set_operations(pdc_console_tty_driver, &pdc_console_tty_ops);
+
+        err = tty_register_driver(pdc_console_tty_driver);
         if (err) {
                 printk(KERN_ERR "Unable to register the PDC console TTY driver\n");
                 return err;
         }
 
-        pdc_console_tty_driver = drv;
-
         return 0;
 }