summaryrefslogtreecommitdiff
path: root/drivers/char
diff options
context:
space:
mode:
authorJason A. Donenfeld <Jason@zx2c4.com>2022-05-09 14:53:24 +0300
committerJason A. Donenfeld <Jason@zx2c4.com>2022-05-18 16:53:53 +0300
commit68c9c8b192c6dae9be6278e98ee44029d5da2d31 (patch)
treebc4b1ebe0d0ec25bfff4a8a9a8181f32ad742078 /drivers/char
parentfed7ef061686cc813b1f3d8d0edc6c35b4d3537b (diff)
downloadlinux-68c9c8b192c6dae9be6278e98ee44029d5da2d31.tar.xz
random: move initialization out of reseeding hot path
Initialization happens once -- by way of credit_init_bits() -- and then it never happens again. Therefore, it doesn't need to be in crng_reseed(), which is a hot path that is called multiple times. It also doesn't make sense to have there, as initialization activity is better associated with initialization routines. After the prior commit, crng_reseed() now won't be called by multiple concurrent callers, which means that we can safely move the "finialize_init" logic into crng_init_bits() unconditionally. Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/random.c42
1 files changed, 19 insertions, 23 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 8b451e8490b5..07200b8f4591 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -265,7 +265,6 @@ static void crng_reseed(void)
unsigned long flags;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
- bool finalize_init = false;
extract_entropy(key, sizeof(key));
@@ -282,28 +281,10 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
- if (!crng_ready()) {
+ if (!crng_ready())
crng_init = CRNG_READY;
- finalize_init = true;
- }
spin_unlock_irqrestore(&base_crng.lock, flags);
memzero_explicit(key, sizeof(key));
- if (finalize_init) {
- process_random_ready_list();
- wake_up_interruptible(&crng_init_wait);
- kill_fasync(&fasync, SIGIO, POLL_IN);
- pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
- pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
- urandom_warning.missed);
- urandom_warning.missed = 0;
- }
- }
}
/*
@@ -835,10 +816,25 @@ static void credit_init_bits(size_t nbits)
new = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
- if (orig < POOL_READY_BITS && new >= POOL_READY_BITS)
- crng_reseed();
- else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
+ if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
+ crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
+ process_random_ready_list();
+ wake_up_interruptible(&crng_init_wait);
+ kill_fasync(&fasync, SIGIO, POLL_IN);
+ pr_notice("crng init done\n");
+ if (unseeded_warning.missed) {
+ pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
+ unseeded_warning.missed);
+ unseeded_warning.missed = 0;
+ }
+ if (urandom_warning.missed) {
+ pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
+ urandom_warning.missed);
+ urandom_warning.missed = 0;
+ }
+ } else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
spin_lock_irqsave(&base_crng.lock, flags);
+ /* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
if (crng_init == CRNG_EMPTY) {
extract_entropy(base_crng.key, sizeof(base_crng.key));
crng_init = CRNG_EARLY;