diff --git a/include/linux/random.h b/include/linux/random.h index 25d02fe5c9b5..fb7ab9de5f36 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -40,6 +40,10 @@ struct rand_pool_info { __u32 buf[0]; }; +struct rnd_state { + __u32 s1, s2, s3; +}; + /* Exported functions */ #ifdef __KERNEL__ @@ -74,6 +78,30 @@ unsigned long randomize_range(unsigned long start, unsigned long end, unsigned l u32 random32(void); void srandom32(u32 seed); +u32 prandom32(struct rnd_state *); + +/* + * Handle minimum values for seeds + */ +static inline u32 __seed(u32 x, u32 m) +{ + return (x < m) ? x + m : x; +} + +/** + * prandom32_seed - set seed for prandom32(). + * @state: pointer to state structure to receive the seed. + * @seed: arbitrary 64-bit value to use as a seed. + */ +static inline void prandom32_seed(struct rnd_state *state, u64 seed) +{ + u32 i = (seed >> 32) ^ (seed << 10) ^ seed; + + state->s1 = __seed(i, 1); + state->s2 = __seed(i, 7); + state->s3 = __seed(i, 15); +} + #endif /* __KERNEL___ */ #endif /* _LINUX_RANDOM_H */ diff --git a/lib/random32.c b/lib/random32.c index 217d5c4b666d..870dc3fc0f0f 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -39,13 +39,16 @@ #include #include -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)<>b) @@ -55,14 +58,7 @@ static u32 __random32(struct rnd_state *state) return (state->s1 ^ state->s2 ^ state->s3); } - -/* - * Handle minimum values for seeds - */ -static inline u32 __seed(u32 x, u32 m) -{ - return (x < m) ? x + m : x; -} +EXPORT_SYMBOL(prandom32); /** * random32 - pseudo random number generator @@ -75,7 +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; } @@ -118,12 +114,12 @@ static int __init random32_init(void) state->s3 = __seed(LCG(state->s2), 15); /* "warm it up" */ - __random32(state); - __random32(state); - __random32(state); - __random32(state); - __random32(state); - __random32(state); + prandom32(state); + prandom32(state); + prandom32(state); + prandom32(state); + prandom32(state); + prandom32(state); } return 0; } @@ -147,7 +143,7 @@ static int __init random32_reseed(void) state->s3 = __seed(seeds[2], 15); /* mix it in */ - __random32(state); + prandom32(state); } return 0; }