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tty: kref the tty driver object
[h-e-n] / drivers / char / tty_io.c
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index ac41af8..47aa437 100644 (file)
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -276,7 +276,7 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index)
                if (device < base || device >= base + p->num)
                        continue;
                *index = device - base;
-               return p;
+               return tty_driver_kref_get(p);
        }
        return NULL;
 }
@@ -320,7 +320,7 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
 
                if (tty_line >= 0 && tty_line <= p->num && p->ops &&
                    p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
-                       res = p;
+                       res = tty_driver_kref_get(p);
                        *line = tty_line;
                        break;
                }
@@ -1410,7 +1410,7 @@ int tty_init_dev(struct tty_driver *driver, int idx,
                        *o_ltp_loc = o_ltp;
                o_tty->termios = *o_tp_loc;
                o_tty->termios_locked = *o_ltp_loc;
-               driver->other->refcount++;
+               tty_driver_kref_get(driver->other);
                if (driver->subtype == PTY_TYPE_MASTER)
                        o_tty->count++;
 
@@ -1438,7 +1438,7 @@ int tty_init_dev(struct tty_driver *driver, int idx,
        /* Compatibility until drivers always set this */
        tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
        tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
-       driver->refcount++;
+       tty_driver_kref_get(driver);
        tty->count++;
 
        /*
@@ -1530,8 +1530,7 @@ static void release_one_tty(struct kref *kref)
        else
                tty_shutdown(tty);
        tty->magic = 0;
-       /* FIXME: locking on tty->driver->refcount */
-       tty->driver->refcount--;
+       tty_driver_kref_put(driver);
        module_put(driver->owner);
 
        file_list_lock();
@@ -1854,7 +1853,7 @@ retry_open:
                        mutex_unlock(&tty_mutex);
                        return -ENXIO;
                }
-               driver = tty->driver;
+               driver = tty_driver_kref_get(tty->driver);
                index = tty->index;
                filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
                /* noctty = 1; */
@@ -1865,14 +1864,14 @@ retry_open:
 #ifdef CONFIG_VT
        if (device == MKDEV(TTY_MAJOR, 0)) {
                extern struct tty_driver *console_driver;
-               driver = console_driver;
+               driver = tty_driver_kref_get(console_driver);
                index = fg_console;
                noctty = 1;
                goto got_driver;
        }
 #endif
        if (device == MKDEV(TTYAUX_MAJOR, 1)) {
-               driver = console_device(&index);
+               driver = tty_driver_kref_get(console_device(&index));
                if (driver) {
                        /* Don't let /dev/console block */
                        filp->f_flags |= O_NONBLOCK;
@@ -1891,6 +1890,7 @@ retry_open:
 got_driver:
        retval = tty_init_dev(driver, index, &tty, 0);
        mutex_unlock(&tty_mutex);
+       tty_driver_kref_put(driver);
        if (retval)
                return retval;
 
@@ -2866,7 +2866,6 @@ int tty_put_char(struct tty_struct *tty, unsigned char ch)
                return tty->ops->put_char(tty, ch);
        return tty->ops->write(tty, &ch, 1);
 }
-
 EXPORT_SYMBOL_GPL(tty_put_char);
 
 struct class *tty_class;
@@ -2909,6 +2908,7 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,
 
        return device_create_drvdata(tty_class, device, dev, NULL, name);
 }
+EXPORT_SYMBOL(tty_register_device);
 
 /**
  *     tty_unregister_device - unregister a tty device
@@ -2926,8 +2926,6 @@ void tty_unregister_device(struct tty_driver *driver, unsigned index)
        device_destroy(tty_class,
                MKDEV(driver->major, driver->minor_start) + index);
 }
-
-EXPORT_SYMBOL(tty_register_device);
 EXPORT_SYMBOL(tty_unregister_device);
 
 struct tty_driver *alloc_tty_driver(int lines)
@@ -2936,27 +2934,70 @@ struct tty_driver *alloc_tty_driver(int lines)
 
        driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
        if (driver) {
+               kref_init(&driver->kref);
                driver->magic = TTY_DRIVER_MAGIC;
                driver->num = lines;
                /* later we'll move allocation of tables here */
        }
        return driver;
 }
+EXPORT_SYMBOL(alloc_tty_driver);
 
-void put_tty_driver(struct tty_driver *driver)
+static void destruct_tty_driver(struct kref *kref)
 {
+       struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
+       int i;
+       struct ktermios *tp;
+       void *p;
+
+       if (driver->flags & TTY_DRIVER_INSTALLED) {
+               /*
+                * Free the termios and termios_locked structures because
+                * we don't want to get memory leaks when modular tty
+                * drivers are removed from the kernel.
+                */
+               for (i = 0; i < driver->num; i++) {
+                       tp = driver->termios[i];
+                       if (tp) {
+                               driver->termios[i] = NULL;
+                               kfree(tp);
+                       }
+                       tp = driver->termios_locked[i];
+                       if (tp) {
+                               driver->termios_locked[i] = NULL;
+                               kfree(tp);
+                       }
+                       if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
+                               tty_unregister_device(driver, i);
+               }
+               p = driver->ttys;
+               proc_tty_unregister_driver(driver);
+               driver->ttys = NULL;
+               driver->termios = driver->termios_locked = NULL;
+               kfree(p);
+               cdev_del(&driver->cdev);
+       }
        kfree(driver);
 }
 
+void tty_driver_kref_put(struct tty_driver *driver)
+{
+       kref_put(&driver->kref, destruct_tty_driver);
+}
+EXPORT_SYMBOL(tty_driver_kref_put);
+
 void tty_set_operations(struct tty_driver *driver,
                        const struct tty_operations *op)
 {
        driver->ops = op;
 };
+EXPORT_SYMBOL(tty_set_operations);
 
-EXPORT_SYMBOL(alloc_tty_driver);
+void put_tty_driver(struct tty_driver *d)
+{
+       tty_driver_kref_put(d);
+}
 EXPORT_SYMBOL(put_tty_driver);
-EXPORT_SYMBOL(tty_set_operations);
 
 /*
  * Called by a tty driver to register itself.
@@ -2968,9 +3009,6 @@ int tty_register_driver(struct tty_driver *driver)
        dev_t dev;
        void **p = NULL;
 
-       if (driver->flags & TTY_DRIVER_INSTALLED)
-               return 0;
-
        if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
                p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
                if (!p)
@@ -3024,6 +3062,7 @@ int tty_register_driver(struct tty_driver *driver)
                    tty_register_device(driver, i, NULL);
        }
        proc_tty_register_driver(driver);
+       driver->flags |= TTY_DRIVER_INSTALLED;
        return 0;
 }
 
@@ -3034,46 +3073,19 @@ EXPORT_SYMBOL(tty_register_driver);
  */
 int tty_unregister_driver(struct tty_driver *driver)
 {
-       int i;
-       struct ktermios *tp;
-       void *p;
-
+#if 0
+       /* FIXME */
        if (driver->refcount)
                return -EBUSY;
-
+#endif
        unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
                                driver->num);
        mutex_lock(&tty_mutex);
        list_del(&driver->tty_drivers);
        mutex_unlock(&tty_mutex);
-
-       /*
-        * Free the termios and termios_locked structures because
-        * we don't want to get memory leaks when modular tty
-        * drivers are removed from the kernel.
-        */
-       for (i = 0; i < driver->num; i++) {
-               tp = driver->termios[i];
-               if (tp) {
-                       driver->termios[i] = NULL;
-                       kfree(tp);
-               }
-               tp = driver->termios_locked[i];
-               if (tp) {
-                       driver->termios_locked[i] = NULL;
-                       kfree(tp);
-               }
-               if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
-                       tty_unregister_device(driver, i);
-       }
-       p = driver->ttys;
-       proc_tty_unregister_driver(driver);
-       driver->ttys = NULL;
-       driver->termios = driver->termios_locked = NULL;
-       kfree(p);
-       cdev_del(&driver->cdev);
        return 0;
 }
+
 EXPORT_SYMBOL(tty_unregister_driver);
 
 dev_t tty_devnum(struct tty_struct *tty)
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