linux-kernel - [PATCH] random: make consistent usage of crng

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Date:   Tue,  8 Mar 2022 11:25:17 -0700
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     linux-kernel@...r.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Theodore Ts'o <tytso@....edu>
Subject: [PATCH] random: make consistent usage of crng_ready()

Rather than sometimes checking `crng_init < 2`, we should always use the
crng_ready() macro, so that should we change anything later, it's
consistent. Additionally, that macro already has a likely() around it,
which means we don't need to open code our own likely() and unlikely()
annotations.

Cc: Dominik Brodowski <linux@...inikbrodowski.net>
Cc: Theodore Ts'o <tytso@....edu>
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 drivers/char/random.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 69591d599338..e37ae7ef039c 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -123,7 +123,7 @@ static void try_to_generate_entropy(void);
  */
 int wait_for_random_bytes(void)
 {
-	if (likely(crng_ready()))
+	if (crng_ready())
 		return 0;
 
 	do {
@@ -289,7 +289,7 @@ static void crng_reseed(bool force)
 		++next_gen;
 	WRITE_ONCE(base_crng.generation, next_gen);
 	WRITE_ONCE(base_crng.birth, jiffies);
-	if (crng_init < 2) {
+	if (!crng_ready()) {
 		crng_init = 2;
 		finalize_init = true;
 	}
@@ -352,7 +352,7 @@ static void crng_make_state(u32 chacha_state[CHACHA_STATE_WORDS],
 	 * ready, we do fast key erasure with the base_crng directly, because
 	 * this is what crng_pre_init_inject() mutates during early init.
 	 */
-	if (unlikely(!crng_ready())) {
+	if (!crng_ready()) {
 		bool ready;
 
 		spin_lock_irqsave(&base_crng.lock, flags);
@@ -795,7 +795,7 @@ static void credit_entropy_bits(size_t nbits)
 		entropy_count = min_t(unsigned int, POOL_BITS, orig + add);
 	} while (cmpxchg(&input_pool.entropy_count, orig, entropy_count) != orig);
 
-	if (crng_init < 2 && entropy_count >= POOL_MIN_BITS)
+	if (!crng_ready() && entropy_count >= POOL_MIN_BITS)
 		crng_reseed(false);
 }
 
-- 
2.35.1