Re: [PATCH akpm-next] random32: minor cleanups and kdoc fix

From: Joe Perches
Date: Wed Feb 12 2014 - 18:44:07 EST


On Wed, 2014-02-12 at 23:43 +0100, Daniel Borkmann wrote:
> These are just some very minor and misc cleanups in the PRNG.

trivia:

> diff --git a/lib/random32.c b/lib/random32.c
[]
> @@ -30,7 +30,6 @@
>
> This affects the seeding procedure by imposing the requirement
> s1 > 1, s2 > 7, s3 > 15, s4 > 127.
> -
> */

Using normal comment block style

/*
*
*/

might be nicer

> #include <linux/types.h>
> @@ -75,15 +74,17 @@ 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);

Maybe:

u32 res = prandom_u32_state(state);

> @@ -201,9 +202,10 @@ static int __init prandom_init(void)
> for_each_possible_cpu(i) {
> struct rnd_state *state = &per_cpu(net_rand_state,i);
>
> - prandom_seed_very_weak(state, (i + jiffies) ^ random_get_entropy());
> + prandom_seed_very_weak(state, (i + jiffies) ^ (u32)random_get_entropy());

This (u32) cast is not necessary.

On 64 bit machines, the high 32 bits of random_get_entropy
are unnecessarily dropped/masked.

The compiler will cast the unsigned long result of the xor
back to u32 anyway.


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