- emphasize bits in the name
- make zero bits lock-free
- simplify logic
diff -r a0689714301a -r 218e9dac90b1 drivers/char/random.c
--- a/drivers/char/random.c Thu Jan 17 20:25:24 2008 -0600
+++ b/drivers/char/random.c Thu Jan 17 20:25:24 2008 -0600
@@ -441,7 +441,7 @@
/*
* This function adds bytes into the entropy "pool". It does not
* update the entropy estimate. The caller should call
- * credit_entropy_store if this is appropriate.
+ * credit_entropy_bits if this is appropriate.
*
* The pool is stirred with a primitive polynomial of the appropriate
* degree, and then twisted. We twist by three bits at a time because
@@ -515,24 +515,22 @@
/*
* Credit (or debit) the entropy store with n bits of entropy
*/
-static void credit_entropy_store(struct entropy_store *r, int nbits)
+static void credit_entropy_bits(struct entropy_store *r, int nbits)
{
unsigned long flags;
+ if (!nbits)
+ return;
+
spin_lock_irqsave(&r->lock, flags);
- if (r->entropy_count + nbits < 0) {
- DEBUG_ENT("negative entropy/overflow (%d+%d)\n",
- r->entropy_count, nbits);
+ DEBUG_ENT("added %d entropy credits to %s\n", nbits, r->name);
+ r->entropy_count += nbits;
+ if (r->entropy_count < 0) {
+ DEBUG_ENT("negative entropy/overflow\n");
r->entropy_count = 0;
- } else if (r->entropy_count + nbits > r->poolinfo->POOLBITS) {
+ } else if (r->entropy_count > r->poolinfo->POOLBITS)
r->entropy_count = r->poolinfo->POOLBITS;
- } else {
- r->entropy_count += nbits;
- if (nbits)
- DEBUG_ENT("added %d entropy credits to %s\n",
- nbits, r->name);
- }
/* should we wake readers? */
if (r == &input_pool && r->entropy_count >= random_read_wakeup_thresh)
@@ -619,8 +617,8 @@
* Round down by 1 bit on general principles,
* and limit entropy entimate to 12 bits.
*/
- credit_entropy_store(&input_pool,
- min_t(int, fls(delta>>1), 11));
+ credit_entropy_bits(&input_pool,
+ min_t(int, fls(delta>>1), 11));
}
out:
preempt_enable();
@@ -703,7 +701,7 @@
bytes = extract_entropy(r->pull, tmp, bytes,
random_read_wakeup_thresh / 8, rsvd);
mix_pool_bytes(r, tmp, bytes);
- credit_entropy_store(r, bytes*8);
+ credit_entropy_bits(r, bytes*8);
}
}
@@ -1074,7 +1072,7 @@
return -EPERM;
if (get_user(ent_count, p))
return -EFAULT;
- credit_entropy_store(&input_pool, ent_count);
+ credit_entropy_bits(&input_pool, ent_count);
return 0;
case RNDADDENTROPY:
if (!capable(CAP_SYS_ADMIN))
@@ -1089,7 +1087,7 @@
size);
if (retval < 0)
return retval;
- credit_entropy_store(&input_pool, ent_count);
+ credit_entropy_bits(&input_pool, ent_count);
return 0;
case RNDZAPENTCNT:
case RNDCLEARPOOL:
--
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