random: account for arch randomness in bits

Rather than accounting in bytes and multiplying (shifting), we can just
account in bits and avoid the shift. The main motivation for this is
there are other patches in flux that expand this code a bit, and
avoiding the duplication of "* 8" everywhere makes things a bit clearer.

Cc: [email protected]
Fixes: 12e45a2 ("random: credit architectural init the exact amount")
Signed-off-by: Jason A. Donenfeld <[email protected]>

Author: zx2c4

drivers/char/random.c

@@ -776,20 +776,20 @@ static struct notifier_block pm_notifier = { .notifier_call = random_pm_notifica
 int __init random_init(const char *command_line)
 {
 	ktime_t now = ktime_get_real();
-	unsigned int i, arch_bytes;
+	unsigned int i, arch_bits;
 	unsigned long entropy;
 
 #if defined(LATENT_ENTROPY_PLUGIN)
 	static const u8 compiletime_seed[BLAKE2S_BLOCK_SIZE] __initconst __latent_entropy;
 	_mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed));
 #endif
 
-	for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE;
+	for (i = 0, arch_bits = BLAKE2S_BLOCK_SIZE * 8;
 	     i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) {
 		if (!arch_get_random_seed_long_early(&entropy) &&
 		    !arch_get_random_long_early(&entropy)) {
 			entropy = random_get_entropy();
-			arch_bytes -= sizeof(entropy);
+			arch_bits -= sizeof(entropy) * 8;
 		}
 		_mix_pool_bytes(&entropy, sizeof(entropy));
 	}
@@ -801,8 +801,8 @@ int __init random_init(const char *command_line)
 	if (crng_ready())
 		crng_reseed();
 	else if (trust_cpu)
-		_credit_init_bits(arch_bytes * 8);
-	used_arch_random = arch_bytes * 8 >= POOL_READY_BITS;
+		_credit_init_bits(arch_bits);
+	used_arch_random = arch_bits >= POOL_READY_BITS;
 
 	WARN_ON(register_pm_notifier(&pm_notifier));