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| author |   Jason A. Donenfeld <Jason@zx2c4.com> | 2022-05-09 13:53:24 +0200 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-05-18 15:53:53 +0200 |
| commit | 68c9c8b192c6dae9be6278e98ee44029d5da2d31 (patch) | |
| tree | bc4b1ebe0d0ec25bfff4a8a9a8181f32ad742078 /drivers/char/random.c | |
| parent | random: avoid initializing twice in credit race (diff) | |
| download | linux-dev-68c9c8b192c6dae9be6278e98ee44029d5da2d31.tar.xz linux-dev-68c9c8b192c6dae9be6278e98ee44029d5da2d31.zip | |
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/random.c')
| -rw-r--r-- | drivers/char/random.c | 42 |
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; |