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random: do not use batches when !crng_ready() 

It's too hard to keep the batches synchronized, and pointless anyway,
since in !crng_ready(), we're updating the base_crng key really often,
where batching only hurts. So instead, if the crng isn't ready, just
call into get_random_bytes(). At this stage nothing is performance
critical anyhow.

Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2022-05-03 14:14:32 +02:00
parent b7b67d1391
commit cbe89e5a37
1 changed files with 11 additions and 3 deletions
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14
drivers/char/random.c
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@ -466,10 +466,8 @@ static void crng_pre_init_inject(const void *input, size_t len, bool account)
if (account) {
crng_init_cnt += min_t(size_t, len, CRNG_INIT_CNT_THRESH - crng_init_cnt);
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
++base_crng.generation;
if (crng_init_cnt >= CRNG_INIT_CNT_THRESH)
crng_init = 1;
}
}
spin_unlock_irqrestore(&base_crng.lock, flags);
@ -625,6 +623,11 @@ u64 get_random_u64(void)
warn_unseeded_randomness(&previous);
if (!crng_ready()) {
_get_random_bytes(&ret, sizeof(ret));
return ret;
}
local_lock_irqsave(&batched_entropy_u64.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u64);
@ -659,6 +662,11 @@ u32 get_random_u32(void)
warn_unseeded_randomness(&previous);
if (!crng_ready()) {
_get_random_bytes(&ret, sizeof(ret));
return ret;
}
local_lock_irqsave(&batched_entropy_u32.lock, flags);
batch = raw_cpu_ptr(&batched_entropy_u32);