提交 d3d47eb2 编写于 作者: D Daniel Borkmann 提交者: Linus Torvalds

lib/random32.c: minor cleanups and kdoc fix

These are just some very minor and misc cleanups in the PRNG.  In
prandom_u32() we store the result in an unsigned long which is
unnecessary as it should be u32 instead that we get from
prandom_u32_state().  prandom_bytes_state()'s comment is in kdoc format,
so change it into such as it's done everywhere else.  Also, use the
normal comment style for the header comment.  Last but not least for
readability, add some newlines.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 b104d6a5
/* /*
This is a maximally equidistributed combined Tausworthe generator * This is a maximally equidistributed combined Tausworthe generator
based on code from GNU Scientific Library 1.5 (30 Jun 2004) * based on code from GNU Scientific Library 1.5 (30 Jun 2004)
*
lfsr113 version: * lfsr113 version:
*
x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n) * x_n = (s1_n ^ s2_n ^ s3_n ^ s4_n)
*
s1_{n+1} = (((s1_n & 4294967294) << 18) ^ (((s1_n << 6) ^ s1_n) >> 13)) * 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)) * 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)) * 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)) * 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). * The period of this generator is about 2^113 (see erratum paper).
*
From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe * From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
Generators", Mathematics of Computation, 65, 213 (1996), 203--213: * Generators", Mathematics of Computation, 65, 213 (1996), 203--213:
http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps * http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps * ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
*
There is an erratum in the paper "Tables of Maximally * There is an erratum in the paper "Tables of Maximally Equidistributed
Equidistributed Combined LFSR Generators", Mathematics of * Combined LFSR Generators", Mathematics of Computation, 68, 225 (1999),
Computation, 68, 225 (1999), 261--269: * 261--269: http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps *
* ... the k_j most significant bits of z_j must be non-zero,
... the k_j most significant bits of z_j must be non- * for each j. (Note: this restriction also applies to the
zero, for each j. (Note: this restriction also applies to the * computer code given in [4], but was mistakenly not mentioned
computer code given in [4], but was mistakenly not mentioned in * in that paper.)
that paper.) *
* This affects the seeding procedure by imposing the requirement
This affects the seeding procedure by imposing the requirement * s1 > 1, s2 > 7, s3 > 15, s4 > 127.
s1 > 1, s2 > 7, s3 > 15, s4 > 127. */
*/
#include <linux/types.h> #include <linux/types.h>
#include <linux/percpu.h> #include <linux/percpu.h>
...@@ -75,15 +73,17 @@ EXPORT_SYMBOL(prandom_u32_state); ...@@ -75,15 +73,17 @@ EXPORT_SYMBOL(prandom_u32_state);
*/ */
u32 prandom_u32(void) u32 prandom_u32(void)
{ {
unsigned long r;
struct rnd_state *state = &get_cpu_var(net_rand_state); 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); put_cpu_var(state);
return r;
return res;
} }
EXPORT_SYMBOL(prandom_u32); EXPORT_SYMBOL(prandom_u32);
/* /**
* prandom_bytes_state - get the requested number of pseudo-random bytes * prandom_bytes_state - get the requested number of pseudo-random bytes
* *
* @state: pointer to state structure holding seeded state. * @state: pointer to state structure holding seeded state.
...@@ -204,6 +204,7 @@ static int __init prandom_init(void) ...@@ -204,6 +204,7 @@ static int __init prandom_init(void)
prandom_seed_very_weak(state, (i + jiffies) ^ random_get_entropy()); prandom_seed_very_weak(state, (i + jiffies) ^ random_get_entropy());
prandom_warmup(state); prandom_warmup(state);
} }
return 0; return 0;
} }
core_initcall(prandom_init); core_initcall(prandom_init);
...@@ -259,6 +260,7 @@ static void __prandom_reseed(bool late) ...@@ -259,6 +260,7 @@ static void __prandom_reseed(bool late)
if (latch && !late) if (latch && !late)
goto out; goto out;
latch = true; latch = true;
for_each_possible_cpu(i) { for_each_possible_cpu(i) {
......
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