Hi Harald,
On 30 October 2017 at 18:58, Harald Freudenberger
<freude@xxxxxxxxxxxxxxxxxx> wrote:
> On 10/27/2017 07:04 PM, PrasannaKumar Muralidharan wrote:
>> 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@xxxxxxxxx>
>> ---
>> drivers/char/hw_random/core.c | 51 +++++++++++++++++++++++++++----------------
>> 1 file changed, 32 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
>> index 9701ac7..be03024 100644
>> --- a/drivers/char/hw_random/core.c
>> +++ b/drivers/char/hw_random/core.c
>> @@ -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;
> Two lines later err is assigned the return value of mutex_lock_interruptible().
> So the -ENODEV value assignment does nothing.
Indeed true. Will change this when I make a v2.
I am even thinking if it makes sense to return error when user writes
"" to rng_current and there is no rng device registered. I think
returning 0 should be fine.
>> 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);
> looks like for me.
> reviewed-by: Harald Freudenberger <freude@xxxxxxxxxxxxxxxxxx>
>
Thank you.
Thanks,
PrasannaKumar
