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authorJoe Eykholt <jeykholt@cisco.com>2010-05-26 14:44:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-27 09:12:52 -0700
commit5960164fde9bc2f2a99e751d3393faea316e7e36 (patch)
treeeb4340c46fd459a9a078a9b994b5e940b68a875e
parent0a14a130cac9c6826bc81a089b12ab5cbb2b97fc (diff)
lib/random32: export pseudo-random number generator for modules
This patch moves the definition of struct rnd_state and the inline __seed() function to linux/random.h. It renames the static __random32() function to prandom32() and exports it for use in modules. prandom32() is useful as a privately-seeded pseudo random number generator that can give the same result every time it is initialized. For FCoE FC-BB-6 VN2VN mode self-selected unique FC address generation, we need an pseudo-random number generator seeded with the 64-bit world-wide port name. A truly random generator or one seeded with randomness won't do because the same sequence of numbers should be generated each time we boot or the link comes up. A prandom32_seed() inline function is added to the header file. It is inlined not for speed, but so the function won't be expanded in the base kernel, but only in the module that uses it. Signed-off-by: Joe Eykholt <jeykholt@cisco.com> Acked-by: Matt Mackall <mpm@selenic.com> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/random.h28
-rw-r--r--lib/random32.c38
2 files changed, 45 insertions, 21 deletions
diff --git a/include/linux/random.h b/include/linux/random.h
index 25d02fe5c9b..fb7ab9de5f3 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 217d5c4b666..870dc3fc0f0 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -39,13 +39,16 @@
#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)
@@ -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;
}