random: replace custom notifier chain with standard one

We previously rolled our own randomness readiness notifier, which only
has two users in the whole kernel. Replace this with a more standard
atomic notifier block that serves the same purpose with less code. Also
unexport the symbols, because no modules use it, only unconditional
builtins. The only drawback is that it's possible for a notification
handler returning the "stop" code to prevent further processing, but
given that there are only two users, and that we're unexporting this
anyway, that doesn't seem like a significant drawback for the
simplification we receive here.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/lib/random32.c b/lib/random32.c
index 3c19820796d0..976632003ec6 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -551,9 +551,11 @@ static void prandom_reseed(struct timer_list *unused)
  * To avoid worrying about whether it's safe to delay that interrupt
  * long enough to seed all CPUs, just schedule an immediate timer event.
  */
-static void prandom_timer_start(struct random_ready_callback *unused)
+static int prandom_timer_start(struct notifier_block *nb,
+			       unsigned long action, void *data)
 {
 	mod_timer(&seed_timer, jiffies);
+	return 0;
 }
 
 #ifdef CONFIG_RANDOM32_SELFTEST
@@ -617,13 +619,13 @@ core_initcall(prandom32_state_selftest);
  */
 static int __init prandom_init_late(void)
 {
-	static struct random_ready_callback random_ready = {
-		.func = prandom_timer_start
+	static struct notifier_block random_ready = {
+		.notifier_call = prandom_timer_start
 	};
-	int ret = add_random_ready_callback(&random_ready);
+	int ret = register_random_ready_notifier(&random_ready);
 
 	if (ret == -EALREADY) {
-		prandom_timer_start(&random_ready);
+		prandom_timer_start(&random_ready, 0, NULL);
 		ret = 0;
 	}
 	return ret;