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Avoid usb reset crashes by making tty_io cdevs truly dynamic

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Avoid usb reset crashes by making tty_io cdevs truly dynamic

Signed-off-by: Richard Watts <rrw@kynesim.co.uk>
Reported-by: Duncan Mackintosh <DMackintosh@cbnl.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Richard Watts 2015-05-19 16:06:53 +01:00 committed by Greg Kroah-Hartman
parent 458e2c82c5
commit a3a10ce342
2 changed files with 17 additions and 9 deletions
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24
drivers/tty/tty_io.c
View file

@ -3152,9 +3152,12 @@ static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
unsigned int index, unsigned int count) unsigned int index, unsigned int count)
{ {
/* init here, since reused cdevs cause crashes */ /* init here, since reused cdevs cause crashes */
cdev_init(&driver->cdevs[index], &tty_fops); driver->cdevs[index] = cdev_alloc();
driver->cdevs[index].owner = driver->owner; if (!driver->cdevs[index])
return cdev_add(&driver->cdevs[index], dev, count); return -ENOMEM;
cdev_init(driver->cdevs[index], &tty_fops);
driver->cdevs[index]->owner = driver->owner;
return cdev_add(driver->cdevs[index], dev, count);
} }
/** /**
@ -3260,8 +3263,10 @@ struct device *tty_register_device_attr(struct tty_driver *driver,
error: error:
put_device(dev); put_device(dev);
if (cdev) if (cdev) {
cdev_del(&driver->cdevs[index]); cdev_del(driver->cdevs[index]);
driver->cdevs[index] = NULL;
}
return ERR_PTR(retval); return ERR_PTR(retval);
} }
EXPORT_SYMBOL_GPL(tty_register_device_attr); EXPORT_SYMBOL_GPL(tty_register_device_attr);
@ -3281,8 +3286,10 @@ void tty_unregister_device(struct tty_driver *driver, unsigned index)
{ {
device_destroy(tty_class, device_destroy(tty_class,
MKDEV(driver->major, driver->minor_start) + index); MKDEV(driver->major, driver->minor_start) + index);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
cdev_del(&driver->cdevs[index]); cdev_del(driver->cdevs[index]);
driver->cdevs[index] = NULL;
}
} }
EXPORT_SYMBOL(tty_unregister_device); EXPORT_SYMBOL(tty_unregister_device);
@ -3347,6 +3354,7 @@ struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
kfree(driver->ports); kfree(driver->ports);
kfree(driver->ttys); kfree(driver->ttys);
kfree(driver->termios); kfree(driver->termios);
kfree(driver->cdevs);
kfree(driver); kfree(driver);
return ERR_PTR(err); return ERR_PTR(err);
} }
@ -3375,7 +3383,7 @@ static void destruct_tty_driver(struct kref *kref)
} }
proc_tty_unregister_driver(driver); proc_tty_unregister_driver(driver);
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
cdev_del(&driver->cdevs[0]); cdev_del(driver->cdevs[0]);
} }
kfree(driver->cdevs); kfree(driver->cdevs);
kfree(driver->ports); kfree(driver->ports);

2
include/linux/tty_driver.h
View file

@ -296,7 +296,7 @@ struct tty_operations {
struct tty_driver { struct tty_driver {
int magic; /* magic number for this structure */ int magic; /* magic number for this structure */
struct kref kref; /* Reference management */ struct kref kref; /* Reference management */
struct cdev *cdevs; struct cdev **cdevs;
struct module *owner; struct module *owner;
const char *driver_name; const char *driver_name;
const char *name; const char *name;