random: remove mostly unused async readiness notifier

The register_random_ready_notifier() notifier is somewhat complicated,
and was already recently rewritten to use notifier blocks. It is only
used now by one consumer in the kernel, vsprintf.c, for which the async
mechanism is really overly complex for what it actually needs. This
commit removes register_random_ready_notifier() and unregister_random_
ready_notifier(), because it just adds complication with little utility,
and changes vsprintf.c to just check on `!rng_is_initialized() &&
!rng_has_arch_random()`, which will eventually be true. Performance-
wise, that code was already using a static branch, so there's basically
no overhead at all to this change.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Petr Mladek <pmladek@suse.com> # for vsprintf.c
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 0 insertions, 48 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 6b8c89378954..16b39d2dead7 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -84,8 +84,6 @@ static DEFINE_STATIC_KEY_FALSE(crng_is_ready);
 /* Various types of waiters for crng_init->CRNG_READY transition. */
 static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
 static struct fasync_struct *fasync;
-static DEFINE_SPINLOCK(random_ready_chain_lock);
-static RAW_NOTIFIER_HEAD(random_ready_chain);
 
 /* Control how we warn userspace. */
 static struct ratelimit_state urandom_warning =
@@ -142,51 +140,6 @@ int wait_for_random_bytes(void)
 }
 EXPORT_SYMBOL(wait_for_random_bytes);
 
-/*
- * Add a callback function that will be invoked when the input
- * pool is initialised.
- *
- * returns: 0 if callback is successfully added
- *	    -EALREADY if pool is already initialised (callback not called)
- */
-int __cold register_random_ready_notifier(struct notifier_block *nb)
-{
-	unsigned long flags;
-	int ret = -EALREADY;
-
-	if (crng_ready())
-		return ret;
-
-	spin_lock_irqsave(&random_ready_chain_lock, flags);
-	if (!crng_ready())
-		ret = raw_notifier_chain_register(&random_ready_chain, nb);
-	spin_unlock_irqrestore(&random_ready_chain_lock, flags);
-	return ret;
-}
-
-/*
- * Delete a previously registered readiness callback function.
- */
-int __cold unregister_random_ready_notifier(struct notifier_block *nb)
-{
-	unsigned long flags;
-	int ret;
-
-	spin_lock_irqsave(&random_ready_chain_lock, flags);
-	ret = raw_notifier_chain_unregister(&random_ready_chain, nb);
-	spin_unlock_irqrestore(&random_ready_chain_lock, flags);
-	return ret;
-}
-
-static void __cold process_random_ready_list(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&random_ready_chain_lock, flags);
-	raw_notifier_call_chain(&random_ready_chain, 0, NULL);
-	spin_unlock_irqrestore(&random_ready_chain_lock, flags);
-}
-
 #define warn_unseeded_randomness() \
 	if (IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) && !crng_ready()) \
 		printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", \
@@ -775,7 +728,6 @@ static void __cold _credit_init_bits(size_t bits)
 	if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
 		crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
 		execute_in_process_context(crng_set_ready, &set_ready);
-		process_random_ready_list();
 		wake_up_interruptible(&crng_init_wait);
 		kill_fasync(&fasync, SIGIO, POLL_IN);
 		pr_notice("crng init done\n");