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 <dan...@iogearbox.net>
Acked-by: Hannes Frederic Sowa <han...@stressinduktion.org>
---
include/linux/random.h | 6 ++++++
lib/random32.c | 5 +++++
2 files changed, 11 insertions(+)
diff --git a/include/linux/random.h b/include/linux/random.h
index e651874..86d4aa7 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -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_init_state_once(void *pcpu_state);
+
+#define prandom_init_once(pcpu_state) \
+ ({ do_once(prandom_init_state_once, (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 36c09fb..b166237 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -256,6 +256,11 @@ static void prandom_seed_full_state(struct rnd_state
__percpu *pcpu_state)
}
}
+void prandom_init_state_once(void *pcpu_state)
+{
+ prandom_seed_full_state((struct rnd_state __percpu *)pcpu_state);
+}
+
/*
* Generate better values after random number generator
* is fully initialized.
--
1.9.3
--
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