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Commit 897ece56 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

random32: add prandom_init_once helper for own rngs 



Add a prandom_init_once() facility that works on the rnd_state, so that
users that are keeping their own state independent from prandom_u32() can
initialize their taus113 per cpu states.

The motivation here is similar to net_get_random_once(): initialize the
state as late as possible in the hope that enough entropy has been
collected for the seeding. prandom_init_once() makes use of the recently
introduced prandom_seed_full_state() helper and is generic enough so that
it could also be used on fast-paths due to the DO_ONCE().

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0dd50d1b

include/linux/random.h

+6 −0
Original line number Diff line number Diff line
@@ -7,6 +7,8 @@ 
#define _LINUX_RANDOM_H



#include <linux/list.h>

#include <linux/once.h>



#include <uapi/linux/random.h>



struct random_ready_callback {
@@ -45,6 +47,10 @@ struct rnd_state { 


u32 prandom_u32_state(struct rnd_state *state);

void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);

void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);



#define prandom_init_once(pcpu_state)			\

	DO_ONCE(prandom_seed_full_state, (pcpu_state))



/**

 * prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)

lib/random32.c

+1 −1
Original line number Diff line number Diff line
@@ -238,7 +238,7 @@ static void __init __prandom_start_seed_timer(void) 
	add_timer(&seed_timer);

}



static void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)

void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state)

{

	int i;