[PATCH 4.9 163/264] random: make consistent usage of crng_ready()

Greg Kroah-Hartman
2022-06-23T17:03:32Z

From: "Jason A. Donenfeld" <Jason@zx2c4.com>

commit a96cfe2d427064325ecbf56df8816c6b871ec285 upstream.

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: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -126,18 +126,13 @@ static void try_to_generate_entropy(void
*/
int wait_for_random_bytes(void)
{
- if (likely(crng_ready()))
- return 0;
-
- do {
+ while (!crng_ready()) {
int ret;
ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
if (ret)
return ret > 0 ? 0 : ret;
-
try_to_generate_entropy();
- } while (!crng_ready());
-
+ }
return 0;
}
EXPORT_SYMBOL(wait_for_random_bytes);
@@ -292,7 +287,7 @@ static void crng_reseed(void)
++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;
}
@@ -360,7 +355,7 @@ static void crng_make_state(u32 chacha_s
* 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);
@@ -800,7 +795,7 @@ static void credit_entropy_bits(size_t n
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();
}

@@ -957,7 +952,7 @@ int __init rand_initialize(void)
extract_entropy(base_crng.key, sizeof(base_crng.key));
++base_crng.generation;

- if (arch_init && trust_cpu && crng_init < 2) {
+ if (arch_init && trust_cpu && !crng_ready()) {
crng_init = 2;
pr_notice("crng init done (trusting CPU's manufacturer)\n");
}
@@ -1546,7 +1541,7 @@ static long random_ioctl(struct file *f,
case RNDRESEEDCRNG:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (crng_init < 2)
+ if (!crng_ready())
return -ENODATA;
crng_reseed();
return 0;