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TTY: move cdev_add to tty_register_device 

We need the /dev/ node not to be available before we call
tty_register_device. Otherwise we might race with open and
tty_struct->port might not be available at that time.

This is not an issue now, but would be a problem after "TTY: use
tty_port_register_device" is applied.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2012-08-08 22:26:44 +02:00 committed by Greg Kroah-Hartman
parent 0019b4089c
commit 7e73eca6a7
2 changed files with 42 additions and 8 deletions
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48
drivers/tty/tty_io.c
View File

@ -3006,6 +3006,15 @@ EXPORT_SYMBOL_GPL(tty_put_char);
struct class *tty_class;
static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
unsigned int index, unsigned int count)
{
/* init here, since reused cdevs cause crashes */
cdev_init(&driver->cdevs[index], &tty_fops);
driver->cdevs[index].owner = driver->owner;
return cdev_add(&driver->cdevs[index], dev, count);
}
/**
* tty_register_device - register a tty device
* @driver: the tty driver that describes the tty device
@ -3028,8 +3037,10 @@ struct class *tty_class;
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
struct device *device)
{
struct device *ret;
char name[64];
dev_t dev = MKDEV(driver->major, driver->minor_start) + index;
bool cdev = false;
if (index >= driver->num) {
printk(KERN_ERR "Attempt to register invalid tty line number "
@ -3042,7 +3053,18 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,
else
tty_line_name(driver, index, name);
return device_create(tty_class, device, dev, NULL, name);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
int error = tty_cdev_add(driver, dev, index, 1);
if (error)
return ERR_PTR(error);
cdev = true;
}
ret = device_create(tty_class, device, dev, NULL, name);
if (IS_ERR(ret) && cdev)
cdev_del(&driver->cdevs[index]);
return ret;
}
EXPORT_SYMBOL(tty_register_device);
@ -3061,6 +3083,8 @@ void tty_unregister_device(struct tty_driver *driver, unsigned index)
{
device_destroy(tty_class,
MKDEV(driver->major, driver->minor_start) + index);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC))
cdev_del(&driver->cdevs[index]);
}
EXPORT_SYMBOL(tty_unregister_device);
@ -3077,6 +3101,7 @@ struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
unsigned long flags)
{
struct tty_driver *driver;
unsigned int cdevs = 1;
int err;
if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
@ -3110,6 +3135,13 @@ struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
err = -ENOMEM;
goto err_free_all;
}
cdevs = lines;
}
driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
if (!driver->cdevs) {
err = -ENOMEM;
goto err_free_all;
}
return driver;
@ -3144,8 +3176,10 @@ static void destruct_tty_driver(struct kref *kref)
tty_unregister_device(driver, i);
}
proc_tty_unregister_driver(driver);
cdev_del(&driver->cdev);
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
cdev_del(&driver->cdevs[0]);
}
kfree(driver->cdevs);
kfree(driver->ports);
kfree(driver->termios);
kfree(driver->ttys);
@ -3195,11 +3229,11 @@ int tty_register_driver(struct tty_driver *driver)
if (error < 0)
goto err;
cdev_init(&driver->cdev, &tty_fops);
driver->cdev.owner = driver->owner;
error = cdev_add(&driver->cdev, dev, driver->num);
if (error)
goto err_unreg_char;
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
error = tty_cdev_add(driver, dev, 0, driver->num);
if (error)
goto err_unreg_char;
}
mutex_lock(&tty_mutex);
list_add(&driver->tty_drivers, &tty_drivers);

2
include/linux/tty_driver.h
View File

@ -289,7 +289,7 @@ struct tty_operations {
struct tty_driver {
int magic; /* magic number for this structure */
struct kref kref; /* Reference management */
struct cdev cdev;
struct cdev *cdevs;
struct module *owner;
const char *driver_name;
const char *name;