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Subject[RFC PATCH 12/41] random: convert add_interrupt_randomness() to queued_entropy API
Date
In an effort to drop __credit_entropy_bits_fast() in favor of the new
__queue_entropy()/__dispatch_queued_entropy_fast() API, convert
add_interrupt_randomness() from the former to the latter.

There is no change in functionality at this point, because
__credit_entropy_bits_fast() has already been reimplemented on top of the
new API before.

Signed-off-by: Nicolai Stange <nstange@suse.de>
---
drivers/char/random.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index e8c86abde901..bd3774c6be4b 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1512,6 +1512,7 @@ void add_interrupt_randomness(int irq, int irq_flags)
unsigned long seed;
int credit = 0;
bool reseed;
+ struct queued_entropy q = { 0 };

if (cycles == 0)
cycles = get_reg(fast_pool, regs);
@@ -1546,24 +1547,27 @@ void add_interrupt_randomness(int irq, int irq_flags)
if (!spin_trylock(&r->lock))
return;

- fast_pool->last = now;
- __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
-
/*
* If we have architectural seed generator, produce a seed and
- * add it to the pool. For the sake of paranoia don't let the
- * architectural seed generator dominate the input from the
- * interrupt noise.
+ * add it to the pool further below. For the sake of paranoia
+ * don't let the architectural seed generator dominate the
+ * input from the interrupt noise.
*/
- if (arch_get_random_seed_long(&seed)) {
- __mix_pool_bytes(r, &seed, sizeof(seed));
- credit = 1;
- }
+ credit = !!arch_get_random_long(&seed);

+ fast_pool->last = now;
fast_pool->count = 0;
-
/* award one bit for the contents of the fast pool */
- reseed = __credit_entropy_bits_fast(r, credit + 1);
+ __queue_entropy(r, &q, (credit + 1) << ENTROPY_SHIFT);
+ __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
+ if (credit) {
+ /*
+ * A seed has been obtained from
+ * arch_get_random_seed_long() above, mix it in.
+ */
+ __mix_pool_bytes(r, &seed, sizeof(seed));
+ }
+ reseed = __dispatch_queued_entropy_fast(r, &q);
spin_unlock(&r->lock);
if (reseed)
crng_reseed(&primary_crng, r);
--
2.26.2
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