random: make add_timer_randomness() fill the nonblocking pool first

Change add_timer_randomness() so that it directs incoming entropy to
the nonblocking pool first if it hasn't been fully initialized yet.
This matches the strategy we use in add_interrupt_randomness(), which
allows us to push the randomness where we need it the most during when
the system is first booting up, so that get_random_bytes() and
/dev/urandom become safe to use as soon as possible.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index f126bd2f69fe4563308d4e838cb4650f422c6695..62923138e77a6e2de7f5cf5116cea37c4d7b065d 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -761,6 +761,7 @@ static struct timer_rand_state input_timer_state;
  */
 static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
 {
+       struct entropy_store    *r;
        struct {
                long jiffies;
                unsigned cycles;
@@ -773,7 +774,8 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
        sample.jiffies = jiffies;
        sample.cycles = random_get_entropy();
        sample.num = num;
-       mix_pool_bytes(&input_pool, &sample, sizeof(sample), NULL);
+       r = nonblocking_pool.initialized ? &input_pool : &nonblocking_pool;
+       mix_pool_bytes(r, &sample, sizeof(sample), NULL);
 
        /*
         * Calculate number of bits of randomness we probably added.
@@ -807,8 +809,7 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
                 * Round down by 1 bit on general principles,
                 * and limit entropy entimate to 12 bits.
                 */
-               credit_entropy_bits(&input_pool,
-                                   min_t(int, fls(delta>>1), 11));
+               credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
        }
        preempt_enable();
 }