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Commit ac3a497f authored by Herbert Xu's avatar Herbert Xu
Browse files

hwrng: core - Do not register device opportunistically 



Currently we only register the device when a valid RNG is added.
However the way it's done is buggy because we test whether there
is a current RNG to determine whether we need to register.  As
the current RNG may be missing due to a reinitialisation error
this can lead to a reregistration of the device.

As the device already has to handle a NULL current RNG anyway,
let's just register the device always and remove the complexity.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 15b66cd5

drivers/char/hw_random/core.c

+12 −11
Original line number Diff line number Diff line
@@ -372,14 +372,14 @@ static DEVICE_ATTR(rng_available, S_IRUGO, 
		   NULL);





static void unregister_miscdev(void)

static void __exit unregister_miscdev(void)

{

	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);

	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);

	misc_deregister(&rng_miscdev);

}



static int register_miscdev(void)

static int __init register_miscdev(void)

{

	int err;
@@ -484,12 +484,6 @@ int hwrng_register(struct hwrng *rng) 
		if (err)

			goto out_unlock;

		set_current_rng(rng);



		err = register_miscdev();

		if (err) {

			drop_current_rng();

			goto out_unlock;

		}

	}

	list_add_tail(&rng->list, &rng_list);
@@ -530,7 +524,6 @@ void hwrng_unregister(struct hwrng *rng) 


	if (list_empty(&rng_list)) {

		mutex_unlock(&rng_mutex);

		unregister_miscdev();

		if (hwrng_fill)

			kthread_stop(hwrng_fill);

	} else
@@ -540,16 +533,24 @@ void hwrng_unregister(struct hwrng *rng) 
}

EXPORT_SYMBOL_GPL(hwrng_unregister);



static void __exit hwrng_exit(void)

static int __init hwrng_modinit(void)

{

	return register_miscdev();

}



static void __exit hwrng_modexit(void)

{

	mutex_lock(&rng_mutex);

	BUG_ON(current_rng);

	kfree(rng_buffer);

	kfree(rng_fillbuf);

	mutex_unlock(&rng_mutex);



	unregister_miscdev();

}



module_exit(hwrng_exit);

module_init(hwrng_modinit);

module_exit(hwrng_modexit);



MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");

MODULE_LICENSE("GPL");