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Subject[RFC PATCH 31/41] random: introduce struct health_test + health_test_reset() placeholders
Date
The to be implemented health tests will maintain some per-CPU state as they
successively process the IRQ samples fed into the resp. fast_pool from
add_interrupt_randomness().

In order to not to clutter future patches with trivialities, introduce
an empty struct health_test supposed to keep said state in the future.
Add a member of this new type to struct fast_pool.

Introduce a health_test_reset() stub, which is supposed to (re)initialize
instances of struct health_test.

Invoke it from the fast_pool_init_accounting() to make sure that a
fast_pool's contained health_test instance gets initialized once before
its first usage.

Make add_interrupt_randomness call fast_pool_init_accounting() earlier:
health test functionality will get invoked before the latter's old location
and it must have been initialized by that time.

Signed-off-by: Nicolai Stange <nstange@suse.de>
---
drivers/char/random.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 37746df53acf..0f56c873a501 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -879,6 +879,11 @@ static void discard_queued_entropy(struct entropy_store *r,
spin_unlock_irqrestore(&r->lock, flags);
}

+struct health_test {};
+
+static void health_test_reset(struct health_test *h)
+{}
+
struct fast_pool {
__u32 pool[4];
unsigned long last;
@@ -886,6 +891,7 @@ struct fast_pool {
unsigned char count;
int event_entropy_shift;
struct queued_entropy q;
+ struct health_test health;
};

/*
@@ -1644,6 +1650,7 @@ static inline void fast_pool_init_accounting(struct fast_pool *f)
return;

f->event_entropy_shift = min_irq_event_entropy_shift();
+ health_test_reset(&f->health);
}

void add_interrupt_randomness(int irq, int irq_flags)
@@ -1674,6 +1681,8 @@ void add_interrupt_randomness(int irq, int irq_flags)
add_interrupt_bench(cycles);
this_cpu_add(net_rand_state.s1, fast_pool->pool[cycles & 3]);

+ fast_pool_init_accounting(fast_pool);
+
if (unlikely(crng_init == 0)) {
if ((fast_pool->count >= 64) &&
crng_fast_load((char *) fast_pool->pool,
@@ -1692,8 +1701,6 @@ void add_interrupt_randomness(int irq, int irq_flags)
if (!spin_trylock(&r->lock))
return;

- fast_pool_init_accounting(fast_pool);
-
if (!fips_enabled) {
/* award one bit for the contents of the fast pool */
nfrac = 1 << ENTROPY_SHIFT;
--
2.26.2
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