On Tue, 04 Sep 2012 21:41:20 -0700
Doug Barton wrote:
> Can you point out where in the source you're seeing these things?
It's in src/sys/dev/random/randomdev_soft.c:
random_yarrow_write()
random_harvest_internal()
random_kthread()
------------------------------------------------------------------
void
random_yarrow_write(void *buf, int count)
{
int i;
u_int chunk;
/*
* Break the input up into HARVESTSIZE chunks. The writer has
too
* much control here, so "estimate" the entropy as zero.
*/
for (i = 0; i < count; i += HARVESTSIZE) {
chunk = HARVESTSIZE;
if (i + chunk >= count)
chunk = (u_int)(count - i);
random_harvest_internal(get_cyclecount(), (char *)buf +
i, chunk, 0, 0, RANDOM_WRITE);
}
}
/* Entropy harvesting routine. This is supposed to be fast; do
* not do anything slow in here!
*/
static void
random_harvest_internal(u_int64_t somecounter, const void *entropy,
u_int count, u_int bits, u_int frac, enum esource origin)
{
struct harvest *event;
KASSERT(origin == RANDOM_START || origin == RANDOM_WRITE ||
origin == RANDOM_KEYBOARD || origin == RANDOM_MOUSE ||
origin == RANDOM_NET || origin == RANDOM_INTERRUPT ||
origin == RANDOM_PURE,
("random_harvest_internal: origin %d invalid\n", origin));
/* Lockless read to avoid lock operations if fifo is full. */
if (harvestfifo[origin].count >= RANDOM_FIFO_MAX)
return;
mtx_lock_spin(&harvest_mtx);
/*
* Don't make the harvest queues too big - help to prevent
low-grade
* entropy swamping
*/
if (harvestfifo[origin].count < RANDOM_FIFO_MAX) {
event = STAILQ_FIRST(&emptyfifo.head);
if (event != NULL) {
/* Add the harvested data to the fifo */
STAILQ_REMOVE_HEAD(&emptyfifo.head, next);
harvestfifo[origin].count++;
event->somecounter = somecounter;
event->size = count;
event->bits = bits;
event->frac = frac;
event->source = origin;
/* XXXX Come back and make this dynamic! */
count = MIN(count, HARVESTSIZE);
memcpy(event->entropy, entropy, count);
STAILQ_INSERT_TAIL(&harvestfifo[origin].head,
event, next);
}
}
mtx_unlock_spin(&harvest_mtx);
}
static void
random_kthread(void *arg __unused)
{
STAILQ_HEAD(, harvest) local_queue;
struct harvest *event = NULL;
int local_count;
enum esource source;
STAILQ_INIT(&local_queue);
local_count = 0;
/* Process until told to stop */
for (; random_kthread_control >= 0;) {
/* Cycle through all the entropy sources */
mtx_lock_spin(&harvest_mtx);
for (source = RANDOM_START; source < ENTROPYSOURCE;
source++) { /*
* Drain entropy source records into a
thread-local
* queue for processing while not holding the
mutex. */
STAILQ_CONCAT(&local_queue,
&harvestfifo[source].head); local_count +=
harvestfifo[source].count; harvestfifo[source].count =
0; }
/*
* Deal with events, if any, dropping the mutex as we
process
* each event. Then push the events back into the empty
* fifo.
*/
if (!STAILQ_EMPTY(&local_queue)) {
mtx_unlock_spin(&harvest_mtx);
STAILQ_FOREACH(event, &local_queue, next)
random_process_event(event);
mtx_lock_spin(&harvest_mtx);
STAILQ_CONCAT(&emptyfifo.head, &local_queue);
emptyfifo.count += local_count;
local_count = 0;
}
mtx_unlock_spin(&harvest_mtx);
KASSERT(local_count == 0, ("random_kthread: local_count
%d", local_count));
/*
* If a queue flush was commanded, it has now happened,
* and we can mark this by resetting the command.
*/
if (random_kthread_control == 1)
random_kthread_control = 0;
/* Work done, so don't belabour the issue */
pause("-", hz / 10);
}
random_set_wakeup_exit(&random_kthread_control);
/* NOTREACHED */
}
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