diff options
authorDaniel Borkmann <>2015-10-08 01:20:38 +0200
committerDavid S. Miller <>2015-10-08 05:26:38 -0700
commit897ece56e714a2cc64e6914cb89a362d7021b36e (patch)
parent0dd50d1b0c003ab4f17597fe1198bb57a2fadc06 (diff)
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: Daniel Borkmann <> Acked-by: Hannes Frederic Sowa <> Acked-by: Alexei Starovoitov <> Signed-off-by: David S. Miller <>
2 files changed, 7 insertions, 1 deletions
diff --git a/include/linux/random.h b/include/linux/random.h
index e651874df2c9..a75840c1aa71 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -7,6 +7,8 @@
#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)
diff --git a/lib/random32.c b/lib/random32.c
index 36c09fb3fec9..12111910ccd0 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -238,7 +238,7 @@ static void __init __prandom_start_seed_timer(void)
-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;