Hi Harald,
On 3 July 2017 at 15:33, Harald Freudenberger <freude@xxxxxxxxxxxxxxxxxx> wrote:
> When a user chooses a rng source via sysfs
> attribute this rng should be sticky, even
> when other sources with better quality to
> register. This patch introduces a simple way
> to remember the user's choise.
>
> Signed-off-by: Harald Freudenberger <freude@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/char/hw_random/core.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index e9dda16..ffd4e36 100644
> --- a/drivers/char/hw_random/core.c
> +++ b/drivers/char/hw_random/core.c
> @@ -28,6 +28,8 @@
> #define RNG_MODULE_NAME "hw_random"
>
> static struct hwrng *current_rng;
> +/* the current rng has been explicitly chosen by user via sysfs */
> +static int cur_rng_set_by_user;
> static struct task_struct *hwrng_fill;
> /* list of registered rngs, sorted decending by quality */
> static LIST_HEAD(rng_list);
> @@ -304,6 +306,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
> 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;
> @@ -444,10 +447,12 @@ int hwrng_register(struct hwrng *rng)
>
> old_rng = current_rng;
> err = 0;
> - if (!old_rng || (rng->quality > old_rng->quality)) {
> + if (!old_rng ||
> + (!cur_rng_set_by_user && rng->quality > old_rng->quality)) {
> /*
> * Set new rng as current as the new rng source
> - * provides better entropy quality.
> + * provides better entropy quality and was not
> + * chosen by userspace.
> */
> err = set_current_rng(rng);
> if (err)
> @@ -479,6 +484,7 @@ void hwrng_unregister(struct hwrng *rng)
> 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;
> --
> 2.7.4
>
Looks good to me. Reviewed-by: PrasannaKumar Muralidharan
<prasannatsmkumar@xxxxxxxxx>.
Regards,
PrasannaKumar
