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Commit 0b9f9b94 authored by Dominik Brodowski's avatar Dominik Brodowski Committed by Greg Kroah-Hartman
Browse files

random: continually use hwgenerator randomness 



commit c321e907aa4803d562d6e70ebed9444ad082f953 upstream.

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: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 811e333c

drivers/char/random.c

+6 −4
Original line number Diff line number Diff line
@@ -2195,13 +2195,15 @@ 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);

}