From: Dominik Brodowski <linux@dominikbrodowski.net>
To: "Jason A . Donenfeld" <Jason@zx2c4.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: [PATCH] random: continually use hwgenerator randomness
Date: Tue, 25 Jan 2022 21:14:57 +0100 [thread overview]
Message-ID: <20220125201457.77292-1-linux@dominikbrodowski.net> (raw)
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>
---
drivers/char/random.c | 10 ++++++----
1 file 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);
}
--
2.34.1
next reply other threads:[~2022-01-25 20:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-25 20:14 Dominik Brodowski [this message]
2022-01-26 16:06 ` [PATCH] random: continually use hwgenerator randomness Jason A. Donenfeld
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