random32: add prandom_reseed_late() and call when nonblocking pool becomes initialized

[~andy/linux] / lib / random32.c

diff --git a/lib/random32.c b/lib/random32.c
index 52280d5526be7e8e021dd204c662d3103e6d6726..9f2f2fb03dfe83bac0529bfd9db11416e59ad91b 100644 (file)
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -141,7 +141,8 @@ void prandom_seed(u32 entropy)
         */
        for_each_possible_cpu (i) {
                struct rnd_state *state = &per_cpu(net_rand_state, i);
-               state->s1 = __seed(state->s1 ^ entropy, 1);
+               state->s1 = __seed(state->s1 ^ entropy, 2);
+               prandom_u32_state(state);
        }
 }
 EXPORT_SYMBOL(prandom_seed);
@@ -158,9 +159,9 @@ static int __init prandom_init(void)
                struct rnd_state *state = &per_cpu(net_rand_state,i);
 
 #define LCG(x) ((x) * 69069)   /* super-duper LCG */
-               state->s1 = __seed(LCG(i + jiffies), 1);
-               state->s2 = __seed(LCG(state->s1), 7);
-               state->s3 = __seed(LCG(state->s2), 15);
+               state->s1 = __seed(LCG(i + jiffies), 2);
+               state->s2 = __seed(LCG(state->s1), 8);
+               state->s3 = __seed(LCG(state->s2), 16);
 
                /* "warm it up" */
                prandom_u32_state(state);
@@ -174,26 +175,69 @@ static int __init prandom_init(void)
 }
 core_initcall(prandom_init);
 
+static void __prandom_timer(unsigned long dontcare);
+static DEFINE_TIMER(seed_timer, __prandom_timer, 0, 0);
+
+static void __prandom_timer(unsigned long dontcare)
+{
+       u32 entropy;
+
+       get_random_bytes(&entropy, sizeof(entropy));
+       prandom_seed(entropy);
+       /* reseed every ~60 seconds, in [40 .. 80) interval with slack */
+       seed_timer.expires = jiffies + (40 * HZ + (prandom_u32() % (40 * HZ)));
+       add_timer(&seed_timer);
+}
+
+static void prandom_start_seed_timer(void)
+{
+       set_timer_slack(&seed_timer, HZ);
+       seed_timer.expires = jiffies + 40 * HZ;
+       add_timer(&seed_timer);
+}
+
 /*
  *     Generate better values after random number generator
  *     is fully initialized.
  */
-static int __init prandom_reseed(void)
+static void __prandom_reseed(bool late)
 {
        int i;
+       unsigned long flags;
+       static bool latch = false;
+       static DEFINE_SPINLOCK(lock);
+
+       /* only allow initial seeding (late == false) once */
+       spin_lock_irqsave(&lock, flags);
+       if (latch && !late)
+               goto out;
+       latch = true;
 
        for_each_possible_cpu(i) {
                struct rnd_state *state = &per_cpu(net_rand_state,i);
                u32 seeds[3];
 
                get_random_bytes(&seeds, sizeof(seeds));
-               state->s1 = __seed(seeds[0], 1);
-               state->s2 = __seed(seeds[1], 7);
-               state->s3 = __seed(seeds[2], 15);
+               state->s1 = __seed(seeds[0], 2);
+               state->s2 = __seed(seeds[1], 8);
+               state->s3 = __seed(seeds[2], 16);
 
                /* mix it in */
                prandom_u32_state(state);
        }
+out:
+       spin_unlock_irqrestore(&lock, flags);
+}
+
+void prandom_reseed_late(void)
+{
+       __prandom_reseed(true);
+}
+
+static int __init prandom_reseed(void)
+{
+       __prandom_reseed(false);
+       prandom_start_seed_timer();
        return 0;
 }
 late_initcall(prandom_reseed);