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hwrng: core - Reset user selected rng by writing "" to rng_current

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User is able to select a chosen rng by writing its name to rng_current
but there is no way to reset it without unbinding the rng. Let user
write "" to rng_current and delesect the chosen rng.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
reviewed-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
PrasannaKumar Muralidharan 2017-10-27 22:34:04 +05:30 committed by Herbert Xu
parent c2afad6c61
commit 142a27f0a7
1 changed files with 32 additions and 19 deletions
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51
drivers/char/hw_random/core.c
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@ -292,26 +292,48 @@ static struct miscdevice rng_miscdev = {
.groups = rng_dev_groups,
};
static int enable_best_rng(void)
{
int ret = -ENODEV;
BUG_ON(!mutex_is_locked(&rng_mutex));
/* rng_list is sorted by quality, use the best (=first) one */
if (!list_empty(&rng_list)) {
struct hwrng *new_rng;
new_rng = list_entry(rng_list.next, struct hwrng, list);
ret = ((new_rng == current_rng) ? 0 : set_current_rng(new_rng));
if (!ret)
cur_rng_set_by_user = 0;
}
return ret;
}
static ssize_t hwrng_attr_current_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t len)
{
int err;
int err = -ENODEV;
struct hwrng *rng;
err = mutex_lock_interruptible(&rng_mutex);
if (err)
return -ERESTARTSYS;
err = -ENODEV;
list_for_each_entry(rng, &rng_list, list) {
if (sysfs_streq(rng->name, buf)) {
err = 0;
cur_rng_set_by_user = 1;
if (rng != current_rng)
if (sysfs_streq(buf, "")) {
err = enable_best_rng();
} else {
list_for_each_entry(rng, &rng_list, list) {
if (sysfs_streq(rng->name, buf)) {
cur_rng_set_by_user = 1;
err = set_current_rng(rng);
break;
break;
}
}
}
mutex_unlock(&rng_mutex);
return err ? : len;
@ -493,17 +515,8 @@ void hwrng_unregister(struct hwrng *rng)
mutex_lock(&rng_mutex);
list_del(&rng->list);
if (current_rng == rng) {
drop_current_rng();
cur_rng_set_by_user = 0;
/* rng_list is sorted by quality, use the best (=first) one */
if (!list_empty(&rng_list)) {
struct hwrng *new_rng;
new_rng = list_entry(rng_list.next, struct hwrng, list);
set_current_rng(new_rng);
}
}
if (current_rng == rng)
enable_best_rng();
if (list_empty(&rng_list)) {
mutex_unlock(&rng_mutex);