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Subject[PATCH, RFC 09/12] random: optimize the entropy_store structure
Date
Use smaller types to slightly shrink the size of the entropy store
structure.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
drivers/char/random.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 6d5e8e6..292e717 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -435,16 +435,16 @@ struct entropy_store {
__u32 *pool;
const char *name;
struct entropy_store *pull;
- int limit;

/* read-write data: */
spinlock_t lock;
- unsigned add_ptr;
- unsigned input_rotate;
+ unsigned short add_ptr;
+ unsigned short input_rotate;
int entropy_count;
int entropy_total;
unsigned int initialized:1;
- bool last_data_init;
+ unsigned int limit:1;
+ unsigned int last_data_init:1;
__u8 last_data[EXTRACT_SIZE];
};

@@ -512,7 +512,7 @@ static void _mix_pool_bytes(struct entropy_store *r, const void *in,

/* mix one byte at a time to simplify size handling and churn faster */
while (nbytes--) {
- w = rol32(*bytes++, input_rotate & 31);
+ w = rol32(*bytes++, input_rotate);
i = (i - 1) & wordmask;

/* XOR in the various taps */
@@ -532,7 +532,7 @@ static void _mix_pool_bytes(struct entropy_store *r, const void *in,
* rotation, so that successive passes spread the
* input bits across the pool evenly.
*/
- input_rotate += i ? 7 : 14;
+ input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
}

ACCESS_ONCE(r->input_rotate) = input_rotate;
@@ -1047,7 +1047,7 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
if (fips_enabled) {
spin_lock_irqsave(&r->lock, flags);
if (!r->last_data_init) {
- r->last_data_init = true;
+ r->last_data_init = 1;
spin_unlock_irqrestore(&r->lock, flags);
trace_extract_entropy(r->name, EXTRACT_SIZE,
r->entropy_count, _RET_IP_);
@@ -1187,7 +1187,7 @@ static void init_std_data(struct entropy_store *r)

r->entropy_count = 0;
r->entropy_total = 0;
- r->last_data_init = false;
+ r->last_data_init = 0;
mix_pool_bytes(r, &now, sizeof(now), NULL);
for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
if (!arch_get_random_long(&rv))
--
1.7.12.rc0.22.gcdd159b


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