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uio: Fix lack of locking in init_uio_class 

There is no locking in init_uio_class so multiple
drivers can race and create multiple uio classes.

Fix this by simplifying the code.   In particular always
register the uio class during module_init and make things
simpler.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Eric W. Biederman 2010-09-14 11:36:27 -07:00 committed by Greg Kroah-Hartman
parent e52eec13cd
commit 3d4f9d76b0
1 changed files with 15 additions and 43 deletions
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58
drivers/uio/uio.c
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@ -45,10 +45,7 @@ static DEFINE_IDR(uio_idr);
static const struct file_operations uio_fops;
/* UIO class infrastructure */
static struct uio_class {
struct kref kref;
struct class *class;
} *uio_class;
static struct class *uio_class;
/* Protect idr accesses */
static DEFINE_MUTEX(minor_lock);
@ -757,55 +754,35 @@ static void uio_major_cleanup(void)
static int init_uio_class(void)
{
int ret = 0;
if (uio_class != NULL) {
kref_get(&uio_class->kref);
goto exit;
}
struct class *class;
int ret;
/* This is the first time in here, set everything up properly */
ret = uio_major_init();
if (ret)
goto exit;
uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
if (!uio_class) {
ret = -ENOMEM;
goto err_kzalloc;
}
kref_init(&uio_class->kref);
uio_class->class = class_create(THIS_MODULE, "uio");
if (IS_ERR(uio_class->class)) {
ret = IS_ERR(uio_class->class);
class = class_create(THIS_MODULE, "uio");
if (IS_ERR(class)) {
ret = IS_ERR(class);
printk(KERN_ERR "class_create failed for uio\n");
goto err_class_create;
}
uio_class = class;
return 0;
err_class_create:
kfree(uio_class);
uio_class = NULL;
err_kzalloc:
uio_major_cleanup();
exit:
return ret;
}
static void release_uio_class(struct kref *kref)
static void release_uio_class(void)
{
/* Ok, we cheat as we know we only have one uio_class */
class_destroy(uio_class->class);
kfree(uio_class);
uio_major_cleanup();
class_destroy(uio_class);
uio_class = NULL;
}
static void uio_class_destroy(void)
{
if (uio_class)
kref_put(&uio_class->kref, release_uio_class);
uio_major_cleanup();
}
/**
@ -828,10 +805,6 @@ int __uio_register_device(struct module *owner,
info->uio_dev = NULL;
ret = init_uio_class();
if (ret)
return ret;
idev = kzalloc(sizeof(*idev), GFP_KERNEL);
if (!idev) {
ret = -ENOMEM;
@ -847,7 +820,7 @@ int __uio_register_device(struct module *owner,
if (ret)
goto err_get_minor;
idev->dev = device_create(uio_class->class, parent,
idev->dev = device_create(uio_class, parent,
MKDEV(uio_major, idev->minor), idev,
"uio%d", idev->minor);
if (IS_ERR(idev->dev)) {
@ -874,13 +847,12 @@ int __uio_register_device(struct module *owner,
err_request_irq:
uio_dev_del_attributes(idev);
err_uio_dev_add_attributes:
device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
device_destroy(uio_class, MKDEV(uio_major, idev->minor));
err_device_create:
uio_free_minor(idev);
err_get_minor:
kfree(idev);
err_kzalloc:
uio_class_destroy();
return ret;
}
EXPORT_SYMBOL_GPL(__uio_register_device);
@ -907,9 +879,8 @@ void uio_unregister_device(struct uio_info *info)
uio_dev_del_attributes(idev);
dev_set_drvdata(idev->dev, NULL);
device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
device_destroy(uio_class, MKDEV(uio_major, idev->minor));
kfree(idev);
uio_class_destroy();
return;
}
@ -917,11 +888,12 @@ EXPORT_SYMBOL_GPL(uio_unregister_device);
static int __init uio_init(void)
{
return 0;
return init_uio_class();
}
static void __exit uio_exit(void)
{
release_uio_class();
}
module_init(uio_init)