diff options
| -rw-r--r-- | drivers/char/hw_random/core.c | 51 |
1 files changed, 32 insertions, 19 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index ff79844890ab..657b8770b6b9 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); |