block: add internal hd part table references

[linux-2.6.git] / lib / random32.c

diff --git a/lib/random32.c b/lib/random32.c
index 4a15ce51cea78f4843106221f3db13745b1eb4d7..fc3545a32771569dda97e8169d79151af8add933 100644 (file)
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -36,15 +36,19 @@
 #include <linux/types.h>
 #include <linux/percpu.h>
 #include <linux/module.h>
+#include <linux/jiffies.h>
 #include <linux/random.h>
 
-struct rnd_state {
-       u32 s1, s2, s3;
-};
-
 static DEFINE_PER_CPU(struct rnd_state, net_rand_state);
 
-static u32 __random32(struct rnd_state *state)
+/**
+ *     prandom32 - seeded pseudo-random number generator.
+ *     @state: pointer to state structure holding seeded state.
+ *
+ *     This is used for pseudo-randomness with no outside seeding.
+ *     For more random results, use random32().
+ */
+u32 prandom32(struct rnd_state *state)
 {
 #define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
 
@@ -54,25 +58,7 @@ static u32 __random32(struct rnd_state *state)
 
        return (state->s1 ^ state->s2 ^ state->s3);
 }
-
-static void __set_random32(struct rnd_state *state, unsigned long s)
-{
-       if (s == 0)
-               s = 1;      /* default seed is 1 */
-
-#define LCG(n) (69069 * n)
-       state->s1 = LCG(s);
-       state->s2 = LCG(state->s1);
-       state->s3 = LCG(state->s2);
-
-       /* "warm it up" */
-       __random32(state);
-       __random32(state);
-       __random32(state);
-       __random32(state);
-       __random32(state);
-       __random32(state);
-}
+EXPORT_SYMBOL(prandom32);
 
 /**
  *     random32 - pseudo random number generator
@@ -85,7 +71,7 @@ u32 random32(void)
 {
        unsigned long r;
        struct rnd_state *state = &get_cpu_var(net_rand_state);
-       r = __random32(state);
+       r = prandom32(state);
        put_cpu_var(state);
        return r;
 }
@@ -96,13 +82,18 @@ EXPORT_SYMBOL(random32);
  *     @seed: seed value
  *
  *     Add some additional seeding to the random32() pool.
- *     Note: this pool is per cpu so it only affects current CPU.
  */
 void srandom32(u32 entropy)
 {
-       struct rnd_state *state = &get_cpu_var(net_rand_state);
-       __set_random32(state, state->s1 ^ entropy);
-       put_cpu_var(state);
+       int i;
+       /*
+        * No locking on the CPUs, but then somewhat random results are, well,
+        * expected.
+        */
+       for_each_possible_cpu (i) {
+               struct rnd_state *state = &per_cpu(net_rand_state, i);
+               state->s1 = __seed(state->s1 ^ entropy, 1);
+       }
 }
 EXPORT_SYMBOL(srandom32);
 
@@ -116,7 +107,19 @@ static int __init random32_init(void)
 
        for_each_possible_cpu(i) {
                struct rnd_state *state = &per_cpu(net_rand_state,i);
-               __set_random32(state, i + jiffies);
+
+#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);
+
+               /* "warm it up" */
+               prandom32(state);
+               prandom32(state);
+               prandom32(state);
+               prandom32(state);
+               prandom32(state);
+               prandom32(state);
        }
        return 0;
 }
@@ -124,18 +127,23 @@ core_initcall(random32_init);
 
 /*
  *     Generate better values after random number generator
- *     is fully initalized.
+ *     is fully initialized.
  */
 static int __init random32_reseed(void)
 {
        int i;
-       unsigned long seed;
 
        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);
 
-               get_random_bytes(&seed, sizeof(seed));
-               __set_random32(state, seed);
+               /* mix it in */
+               prandom32(state);
        }
        return 0;
 }