On Wed, Jan 25, 2012 at 07:16:41PM +0000, Mark Murray wrote:
> I thought you were going to do this as a function? It would be
> slightly neater to do it that way.
>
> Looks good! Are you sure this needs no locking or volatile
> variables?
Now with function, volatile, atomic and even enum:
--- sys/libkern.h.old 2012-01-16 07:15:12.000000000 +0400
+++ sys/libkern.h 2012-01-26 06:01:51.000000000 +0400
@@ -72,6 +72,8 @@ static __inline quad_t qabs(quad_t a) {
/* Prototypes for non-quad routines. */
struct malloc_type;
+enum arc4_is { ARC4_ENTR_NONE, ARC4_ENTR_HAVE, ARC4_ENTR_DONE };
+void arc4rand_iniseed_state(enum arc4_is state);
uint32_t arc4random(void);
void arc4rand(void *ptr, u_int len, int reseed);
int bcmp(const void *, const void *, size_t);
--- dev/random/randomdev_soft.c.old 2011-03-02 01:42:19.000000000 +0300
+++ dev/random/randomdev_soft.c 2012-01-26 06:04:05.000000000 +0400
@@ -366,6 +366,7 @@ random_yarrow_unblock(void)
selwakeuppri(&random_systat.rsel, PUSER);
wakeup(&random_systat);
}
+ arc4rand_iniseed_state(ARC4_ENTR_HAVE);
}
static int
--- libkern/arc4random.c.old 2008-08-08 01:51:09.000000000 +0400
+++ libkern/arc4random.c 2012-01-26 06:01:07.000000000 +0400
@@ -24,6 +24,7 @@ __FBSDID("$FreeBSD: src/sys/libkern/arc4
#define ARC4_RESEED_SECONDS 300
#define ARC4_KEYBYTES (256 / 8)
+static volatile enum arc4_is iniseed_state = ARC4_ENTR_NONE;
static u_int8_t arc4_i, arc4_j;
static int arc4_numruns = 0;
static u_int8_t arc4_sbox[256];
@@ -74,6 +75,7 @@ arc4_randomstir (void)
/* Reset for next reseed cycle. */
arc4_t_reseed = tv_now.tv_sec + ARC4_RESEED_SECONDS;
arc4_numruns = 0;
+ arc4rand_iniseed_state(ARC4_ENTR_DONE);
/*
* Throw away the first N words of output, as suggested in the
@@ -103,6 +105,24 @@ arc4_init(void)
SYSINIT(arc4_init, SI_SUB_LOCK, SI_ORDER_ANY, arc4_init, NULL);
+void
+arc4rand_iniseed_state(enum arc4_is state)
+{
+ switch (state) {
+ case ARC4_ENTR_NONE:
+ atomic_store_rel_int(&iniseed_state, state);
+ break;
+ case ARC4_ENTR_HAVE:
+ if (iniseed_state == ARC4_ENTR_NONE)
+ atomic_store_rel_int(&iniseed_state, state);
+ break;
+ case ARC4_ENTR_DONE:
+ if (iniseed_state == ARC4_ENTR_HAVE)
+ atomic_store_rel_int(&iniseed_state, state);
+ break;
+ }
+}
+
/*
* Generate a random byte.
*/
@@ -130,7 +150,7 @@ arc4rand(void *ptr, u_int len, int resee
struct timeval tv;
getmicrouptime(&tv);
- if (reseed ||
+ if (reseed || iniseed_state == ARC4_ENTR_HAVE ||
(arc4_numruns > ARC4_RESEED_BYTES) ||
(tv.tv_sec > arc4_t_reseed))
arc4_randomstir();
--
http://ache.vniz.net/
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