Hi Harald,
> Hello PrasannaKumar
>
> here is now a version which combines patch 2 and patch 3 together
> according to your suggestions:
>
> ========== cut ==========
>
> From: Harald Freudenberger <freude@xxxxxxxxxxxxxxxxxx>
> Date: Fri, 30 Jun 2017 17:06:40 +0200
> Subject: [PATCH 2/2] crypto: hwrng remember rng chosen by user
>
> 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 choice. This is
> reflected by a new sysfs attribute file 'rng_selected'
> which shows if the current rng has been chosen by
> userspace. The new attribute file shows '1' for user
> selected rng and '0' otherwise.
>
> Signed-off-by: Harald Freudenberger <freude@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/char/hw_random/core.c | 21 +++++++++++++++++++--
> 1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index e9dda16..9701ac7 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;
> @@ -352,16 +355,27 @@ static ssize_t hwrng_attr_available_show(struct device *dev,
> return strlen(buf);
> }
>
> +static ssize_t hwrng_attr_selected_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + return snprintf(buf, PAGE_SIZE, "%d\n", cur_rng_set_by_user);
> +}
> +
> static DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
> hwrng_attr_current_show,
> hwrng_attr_current_store);
> static DEVICE_ATTR(rng_available, S_IRUGO,
> hwrng_attr_available_show,
> NULL);
> +static DEVICE_ATTR(rng_selected, S_IRUGO,
> + hwrng_attr_selected_show,
> + NULL);
>
> static struct attribute *rng_dev_attrs[] = {
> &dev_attr_rng_current.attr,
> &dev_attr_rng_available.attr,
> + &dev_attr_rng_selected.attr,
> NULL
> };
>
> @@ -444,10 +458,12 @@ 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 +495,7 @@ 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
>
> ========== cut ==========
>
Good work, patch looks good to me. Reviewed-by: PrasannaKumar
Muralidharan <prasannatsmkumar@xxxxxxxxx>.
I am wondering if you want to make a v2 of the whole series. You can
just put your patch 1 and 2 and send it again with description.
Requiring a v2 depends on how Herbert prefers to take patches in.
Herbert, Do you prefer a v2 of the patch series or you can take this
version of patch 2?
Note: If you are re-posting this patch as v2 please add my reviewed by
tag for both the patches.
Regards,
PrasannaKumar
