[RFC PATCH 30/41] random: add a queued_entropy instance to struct fast_pool

[Nicolai Stange]

When health tests are introduced with upcoming patches, it will become
necessary to keep entropy queued across add_interrupt_randomness()
invocations for later dispatch to the global balance.

Prepare for this by adding a struct queued_entropy member to the per-CPU
fast_pool. Use it in place of that queue with automatic storage duration
in add_interrupt_randomness().

Signed-off-by: Nicolai Stange <nsta...@suse.de>
---
 drivers/char/random.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 55e784a5a2ec..37746df53acf 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -885,6 +885,7 @@ struct fast_pool {
        unsigned short  reg_idx;
        unsigned char   count;
        int             event_entropy_shift;
+       struct queued_entropy   q;
 };
 
 /*
@@ -1655,7 +1656,7 @@ void add_interrupt_randomness(int irq, int irq_flags)
        __u32                   c_high, j_high;
        __u64                   ip;
        bool                    reseed;
-       struct queued_entropy   q = { 0 };
+       struct queued_entropy   *q = &fast_pool->q;
        unsigned int            nfrac;
 
        if (cycles == 0)
@@ -1700,9 +1701,9 @@ void add_interrupt_randomness(int irq, int irq_flags)
                nfrac = fast_pool_entropy(fast_pool->count,
                                          fast_pool->event_entropy_shift);
        }
-       __queue_entropy(r, &q, nfrac);
+       __queue_entropy(r, q, nfrac);
        __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
-       reseed = __dispatch_queued_entropy_fast(r, &q);
+       reseed = __dispatch_queued_entropy_fast(r, q);
        spin_unlock(&r->lock);
 
        fast_pool->last = now;
-- 
2.26.2