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Commit 142a27f0 authored by PrasannaKumar Muralidharan's avatar PrasannaKumar Muralidharan Committed by Herbert Xu
Browse files

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



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: default avatarPrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
reviewed-by: default avatarHarald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent c2afad6c

drivers/char/hw_random/core.c

+32 −19
Original line number Diff line number Diff line
@@ -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;



	if (sysfs_streq(buf, "")) {

		err = enable_best_rng();

	} else {

		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)

				err = set_current_rng(rng);

				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);