From 7e73eca6a7b2967423902a4543821bb97cbbe698 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Wed, 8 Aug 2012 22:26:44 +0200 Subject: [PATCH] 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 Acked-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_io.c | 48 ++++++++++++++++++++++++++++++++------ include/linux/tty_driver.h | 2 +- 2 files changed, 42 insertions(+), 8 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 4d9898c2b641..28c3e869ebba 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -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); diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h index 44e05b75d573..dd976cfb6131 100644 --- a/include/linux/tty_driver.h +++ b/include/linux/tty_driver.h @@ -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;