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authorDominik Brodowski <linux@dominikbrodowski.net>2022-01-25 21:14:57 +0100
committerJason A. Donenfeld <Jason@zx2c4.com>2022-02-04 19:22:32 +0100
commitc321e907aa4803d562d6e70ebed9444ad082f953 (patch)
tree716a3613f8cb1540f947a4aece0ae81bb960904a
parentd2a02e3c8bb6b347818518edff5a4b40ff52d6d8 (diff)
random: continually use hwgenerator randomness
The rngd kernel thread may sleep indefinitely if the entropy count is kept above random_write_wakeup_bits by other entropy sources. To make best use of multiple sources of randomness, mix entropy from hardware RNGs into the pool at least once within CRNG_RESEED_INTERVAL. Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
-rw-r--r--drivers/char/random.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 68613f0b6887..3e133d9583a0 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2205,13 +2205,15 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
return;
}
- /* Suspend writing if we're above the trickle threshold.
+ /* Throttle writing if we're above the trickle threshold.
* We'll be woken up again once below random_write_wakeup_thresh,
- * or when the calling thread is about to terminate.
+ * when the calling thread is about to terminate, or once
+ * CRNG_RESEED_INTERVAL has lapsed.
*/
- wait_event_interruptible(random_write_wait,
+ wait_event_interruptible_timeout(random_write_wait,
!system_wq || kthread_should_stop() ||
- POOL_ENTROPY_BITS() <= random_write_wakeup_bits);
+ POOL_ENTROPY_BITS() <= random_write_wakeup_bits,
+ CRNG_RESEED_INTERVAL);
mix_pool_bytes(buffer, count);
credit_entropy_bits(entropy);
}