This patch introduces a new sysfs attribute file 'rng_selected'
which shows the the rng chosen by userspace.
If a rng source is chosen by user via echo some valid string
to rng_current there should be a way to signal this choice to
userspace. The new attribute file 'rng_selected' shows either
the name of the rng chosen or 'none'.
Signed-off-by: Harald Freudenberger <freude@xxxxxxxxxxxxxxxxxx>
---
drivers/char/hw_random/core.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index ffd4e36..6a6276a 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -28,8 +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;
+/* the rng explicitly selected by user via sysfs */
+static struct hwrng *selected_rng;
static struct task_struct *hwrng_fill;
/* list of registered rngs, sorted decending by quality */
static LIST_HEAD(rng_list);
@@ -306,7 +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;
+ selected_rng = rng;
if (rng != current_rng)
err = set_current_rng(rng);
break;
@@ -355,16 +355,28 @@ 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, "%s\n",
+ selected_rng ? selected_rng->name : "none");
+}
+
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
};
@@ -448,7 +460,7 @@ int hwrng_register(struct hwrng *rng)
old_rng = current_rng;
err = 0;
if (!old_rng ||
- (!cur_rng_set_by_user && rng->quality > old_rng->quality)) {
+ (!selected_rng && rng->quality > old_rng->quality)) {
/*
* Set new rng as current as the new rng source
* provides better entropy quality and was not
@@ -484,7 +496,7 @@ void hwrng_unregister(struct hwrng *rng)
list_del(&rng->list);
if (current_rng == rng) {
drop_current_rng();
- cur_rng_set_by_user = 0;
+ selected_rng = NULL;
/* rng_list is sorted by quality, use the best (=first) one */
if (!list_empty(&rng_list)) {
struct hwrng *new_rng;
--
2.7.4
