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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: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2014-12-23 16:40:19 +11:00
parent 15b66cd542
commit ac3a497f13
1 changed files with 12 additions and 11 deletions
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23
drivers/char/hw_random/core.c
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@ -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");