summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--lib/random32.c76
1 files changed, 39 insertions, 37 deletions
diff --git a/lib/random32.c b/lib/random32.c
index 614896778700..fa5da61ce7ad 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -1,37 +1,35 @@
/*
- This is a maximally equidistributed combined Tausworthe generator
- based on code from GNU Scientific Library 1.5 (30 Jun 2004)
-
- lfsr113 version:
-
- x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
-
- s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
- s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
- s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
- s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
-
- The period of this generator is about 2^113 (see erratum paper).
-
- From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
- Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
- http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
- ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
-
- There is an erratum in the paper "Tables of Maximally
- Equidistributed Combined LFSR Generators", Mathematics of
- Computation, 68, 225 (1999), 261--269:
- http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
-
- ... the k_j most significant bits of z_j must be non-
- zero, for each j. (Note: this restriction also applies to the
- computer code given in [4], but was mistakenly not mentioned in
- that paper.)
-
- This affects the seeding procedure by imposing the requirement
- s1 > 1, s2 > 7, s3 > 15, s4 > 127.
-
-*/
+ * This is a maximally equidistributed combined Tausworthe generator
+ * based on code from GNU Scientific Library 1.5 (30 Jun 2004)
+ *
+ * lfsr113 version:
+ *
+ * x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
+ *
+ * s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13))
+ * s2_{n+1} = (((s2_n & 4294967288) << 2) ^ (((s2_n << 2) ^ s2_n) >> 27))
+ * s3_{n+1} = (((s3_n & 4294967280) << 7) ^ (((s3_n << 13) ^ s3_n) >> 21))
+ * s4_{n+1} = (((s4_n & 4294967168) << 13) ^ (((s4_n << 3) ^ s4_n) >> 12))
+ *
+ * The period of this generator is about 2^113 (see erratum paper).
+ *
+ * From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
+ * Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
+ * http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
+ * ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
+ *
+ * There is an erratum in the paper "Tables of Maximally Equidistributed
+ * Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
+ * 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
+ *
+ * ... the k_j most significant bits of z_j must be non-zero,
+ * for each j. (Note: this restriction also applies to the
+ * computer code given in [4], but was mistakenly not mentioned
+ * in that paper.)
+ *
+ * This affects the seeding procedure by imposing the requirement
+ * s1 > 1, s2 > 7, s3 > 15, s4 > 127.
+ */
#include <linux/types.h>
#include <linux/percpu.h>
@@ -75,15 +73,17 @@ EXPORT_SYMBOL(prandom_u32_state);
*/
u32 prandom_u32(void)
{
- unsigned long r;
struct rnd_state *state = &get_cpu_var(net_rand_state);
- r = prandom_u32_state(state);
+ u32 res;
+
+ res = prandom_u32_state(state);
put_cpu_var(state);
- return r;
+
+ return res;
}
EXPORT_SYMBOL(prandom_u32);
-/*
+/**
* prandom_bytes_state - get the requested number of pseudo-random bytes
*
* @state: pointer to state structure holding seeded state.
@@ -204,6 +204,7 @@ static int __init prandom_init(void)
prandom_seed_very_weak(state, (i + jiffies) ^ random_get_entropy());
prandom_warmup(state);
}
+
return 0;
}
core_initcall(prandom_init);
@@ -259,6 +260,7 @@ static void __prandom_reseed(bool late)
if (latch && !late)
goto out;
+
latch = true;
for_each_possible_cpu(i) {