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path: root/drivers/char/random.c
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Diffstat (limited to 'drivers/char/random.c')
-rw-r--r--drivers/char/random.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 1838aa3d24fe..7ce1ac4baa6d 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -407,7 +407,7 @@ struct entropy_store {
/* read-write data: */
spinlock_t lock;
unsigned add_ptr;
- int entropy_count;
+ int entropy_count; /* Must at no time exceed ->POOLBITS! */
int input_rotate;
};
@@ -520,6 +520,7 @@ static void mix_pool_bytes(struct entropy_store *r, const void *in, int bytes)
static void credit_entropy_bits(struct entropy_store *r, int nbits)
{
unsigned long flags;
+ int entropy_count;
if (!nbits)
return;
@@ -527,20 +528,20 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
spin_lock_irqsave(&r->lock, flags);
DEBUG_ENT("added %d entropy credits to %s\n", nbits, r->name);
- r->entropy_count += nbits;
- if (r->entropy_count < 0) {
+ entropy_count = r->entropy_count;
+ entropy_count += nbits;
+ if (entropy_count < 0) {
DEBUG_ENT("negative entropy/overflow\n");
- r->entropy_count = 0;
- } else if (r->entropy_count > r->poolinfo->POOLBITS)
- r->entropy_count = r->poolinfo->POOLBITS;
+ entropy_count = 0;
+ } else if (entropy_count > r->poolinfo->POOLBITS)
+ entropy_count = r->poolinfo->POOLBITS;
+ r->entropy_count = entropy_count;
/* should we wake readers? */
- if (r == &input_pool &&
- r->entropy_count >= random_read_wakeup_thresh) {
+ if (r == &input_pool && entropy_count >= random_read_wakeup_thresh) {
wake_up_interruptible(&random_read_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);
}
-
spin_unlock_irqrestore(&r->lock, flags);
}