random32: add prandom_init_once helper for own rngs (897ece56) · Commits · 戴 / test

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:

Daniel Borkmann <daniel@iogearbox.net> Acked-by:

Hannes Frederic Sowa <hannes@stressinduktion.org> Acked-by:

Alexei Starovoitov <ast@kernel.org> Signed-off-by:

David S. Miller <davem@davemloft.net>

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;

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