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 <[email protected]>
---
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;
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);
--
2.10.0
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 <[email protected]>
> ---
> 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;
> 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);
That's a really good idea. I also thought about something like that.
regards
Harald Freudenberger
Hi Harald,
On 30 October 2017 at 13:40, Harald Freudenberger
<[email protected]> wrote:
> That's a really good idea. I also thought about something like that.
Do you mind reviewing the code?
Thanks,
PrasannaKumar
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 <[email protected]>
> ---
> 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.
> 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 <[email protected]>
Hi Harald,
On 30 October 2017 at 18:58, Harald Freudenberger
<[email protected]> 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 <[email protected]>
>> ---
>> 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 <[email protected]>
>
Thank you.
Thanks,
PrasannaKumar
On Fri, Oct 27, 2017 at 10:34:04PM +0530, 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 <[email protected]>
Patch applied. Thanks.
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt