From c90e453916bd4d74297303d000f011cdb47a7d94 Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Sun, 13 Feb 2022 21:46:28 +0100 Subject: [PATCH] hwrng: core - do not bother to order list of devices by quality There is no real reason why this list needs to be kept ordered by the driver-provided quality value -- a value which is set only by a handful of hw_random devices anyway. Cc: Herbert Xu Cc: Jason A. Donenfeld Signed-off-by: Dominik Brodowski Signed-off-by: Herbert Xu --- drivers/char/hw_random/core.c | 36 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 20 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index f327f7493585..6f09f4e5af20 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -31,7 +31,7 @@ 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 */ +/* list of registered rngs */ static LIST_HEAD(rng_list); /* Protects rng_list and current_rng */ static DEFINE_MUTEX(rng_mutex); @@ -297,24 +297,28 @@ static struct miscdevice rng_miscdev = { static int enable_best_rng(void) { + struct hwrng *rng, *new_rng = NULL; 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; - } else { + /* no rng to use? */ + if (list_empty(&rng_list)) { drop_current_rng(); cur_rng_set_by_user = 0; - ret = 0; + return 0; } + /* use the rng which offers the best quality */ + list_for_each_entry(rng, &rng_list, list) { + if (!new_rng || rng->quality > new_rng->quality) + new_rng = rng; + } + + ret = ((new_rng == current_rng) ? 0 : set_current_rng(new_rng)); + if (!ret) + cur_rng_set_by_user = 0; + return ret; } @@ -475,7 +479,6 @@ int hwrng_register(struct hwrng *rng) { int err = -EINVAL; struct hwrng *tmp; - struct list_head *rng_list_ptr; bool is_new_current = false; if (!rng->name || (!rng->data_read && !rng->read)) @@ -489,18 +492,11 @@ int hwrng_register(struct hwrng *rng) if (strcmp(tmp->name, rng->name) == 0) goto out_unlock; } + list_add_tail(&rng->list, &rng_list); init_completion(&rng->cleanup_done); complete(&rng->cleanup_done); - /* rng_list is sorted by decreasing quality */ - list_for_each(rng_list_ptr, &rng_list) { - tmp = list_entry(rng_list_ptr, struct hwrng, list); - if (tmp->quality < rng->quality) - break; - } - list_add_tail(&rng->list, rng_list_ptr); - if (!current_rng || (!cur_rng_set_by_user && rng->quality > current_rng->quality)) { /* -- 2.11.0