[PATCH] powerpc: HVC init race

I've been hitting a crash on boot where tty_open is being called before the
hvc console driver setup is complete.  This fixes the problem.

Thanks to benh for his help on this.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 18 insertions, 14 deletions

diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index f65b2e14a485..a94c5b0cac52 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -823,34 +823,38 @@ EXPORT_SYMBOL(hvc_remove);
  * interfaces start to become available. */
 int __init hvc_init(void)
 {
+        struct tty_driver *drv;
+
         /* We need more than hvc_count adapters due to hotplug additions. */
-        hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
-        if (!hvc_driver)
+        drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
+        if (!drv)
                 return -ENOMEM;
 
-        hvc_driver->owner = THIS_MODULE;
-        hvc_driver->devfs_name = "hvc/";
-        hvc_driver->driver_name = "hvc";
-        hvc_driver->name = "hvc";
-        hvc_driver->major = HVC_MAJOR;
-        hvc_driver->minor_start = HVC_MINOR;
-        hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
-        hvc_driver->init_termios = tty_std_termios;
-        hvc_driver->flags = TTY_DRIVER_REAL_RAW;
-        tty_set_operations(hvc_driver, &hvc_ops);
+        drv->owner = THIS_MODULE;
+        drv->devfs_name = "hvc/";
+        drv->driver_name = "hvc";
+        drv->name = "hvc";
+        drv->major = HVC_MAJOR;
+        drv->minor_start = HVC_MINOR;
+        drv->type = TTY_DRIVER_TYPE_SYSTEM;
+        drv->init_termios = tty_std_termios;
+        drv->flags = TTY_DRIVER_REAL_RAW;
+        tty_set_operations(drv, &hvc_ops);
 
         /* Always start the kthread because there can be hotplug vty adapters
          * added later. */
         hvc_task = kthread_run(khvcd, NULL, "khvcd");
         if (IS_ERR(hvc_task)) {
                 panic("Couldn't create kthread for console.\n");
-                put_tty_driver(hvc_driver);
+                put_tty_driver(drv);
                 return -EIO;
         }
 
-        if (tty_register_driver(hvc_driver))
+        if (tty_register_driver(drv))
                 panic("Couldn't register hvc console driver\n");
 
+        mb();
+        hvc_driver = drv;
         return 0;
 }
 module_init(hvc_init);