tty: use krefs to protect driver module counts

[linux-2.6-omap-h63xx.git] / drivers / char / tty_io.c

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 310e0703e4a1281d172717ae5933e25946d9e253..fa162c93ee025a89188856da71ffdf54a3ffc4aa 100644 (file)
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1293,6 +1293,12 @@ static int init_dev(struct tty_driver *driver, int idx,
                o_tty = alloc_tty_struct();
                if (!o_tty)
                        goto free_mem_out;
+               if (!try_module_get(driver->other->owner)) {
+                       /* This cannot in fact currently happen */
+                       free_tty_struct(o_tty);
+                       o_tty = NULL;
+                       goto free_mem_out;
+               }
                initialize_tty_struct(o_tty);
                o_tty->driver = driver->other;
                o_tty->ops = driver->ops;
@@ -1411,8 +1417,10 @@ end_init:
        /* Release locally allocated memory ... nothing placed in slots */
 free_mem_out:
        kfree(o_tp);
-       if (o_tty)
+       if (o_tty) {
+               module_put(o_tty->driver->owner);
                free_tty_struct(o_tty);
+       }
        kfree(ltp);
        kfree(tp);
        free_tty_struct(tty);
@@ -1447,6 +1455,7 @@ release_mem_out:
 static void release_one_tty(struct kref *kref)
 {
        struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
+       struct tty_driver *driver = tty->driver;
        int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
        struct ktermios *tp;
        int idx = tty->index;
@@ -1471,6 +1480,7 @@ static void release_one_tty(struct kref *kref)
        tty->magic = 0;
        /* FIXME: locking on tty->driver->refcount */
        tty->driver->refcount--;
+       module_put(driver->owner);
 
        file_list_lock();
        list_del_init(&tty->tty_files);
@@ -1506,20 +1516,15 @@ EXPORT_SYMBOL(tty_kref_put);
  *     of ttys that the driver keeps.
  *             FIXME: should we require tty_mutex is held here ??
  *
- *     FIXME: We want to defer the module put of the driver to the
- *     destructor.
  */
 static void release_tty(struct tty_struct *tty, int idx)
 {
-       struct tty_driver *driver = tty->driver;
-
        /* This should always be true but check for the moment */
        WARN_ON(tty->index != idx);
 
        if (tty->link)
                tty_kref_put(tty->link);
        tty_kref_put(tty);
-       module_put(driver->owner);
 }
 
 /*