Module Name: src
Committed By: tls
Date: Fri Jan 1 16:09:00 UTC 2016
Modified Files:
src/sys/kern: kern_rndq.c
Log Message:
Fix callout-skew source so it runs only when needed (remove second callout,
eliminate race).
To generate a diff of this commit:
cvs rdiff -u -r1.73 -r1.74 src/sys/kern/kern_rndq.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_rndq.c
diff -u src/sys/kern/kern_rndq.c:1.73 src/sys/kern/kern_rndq.c:1.74
--- src/sys/kern/kern_rndq.c:1.73 Sat Aug 29 10:00:19 2015
+++ src/sys/kern/kern_rndq.c Fri Jan 1 16:09:00 2016
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_rndq.c,v 1.73 2015/08/29 10:00:19 mlelstv Exp $ */
+/* $NetBSD: kern_rndq.c,v 1.74 2016/01/01 16:09:00 tls Exp $ */
/*-
* Copyright (c) 1997-2013 The NetBSD Foundation, Inc.
@@ -32,7 +32,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.73 2015/08/29 10:00:19 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.74 2016/01/01 16:09:00 tls Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
@@ -407,8 +407,8 @@ rnd_dv_estimate(krndsource_t *rs, uint32
#if defined(__HAVE_CPU_COUNTER)
static struct {
kmutex_t lock;
+ int iter;
struct callout callout;
- struct callout stop_callout;
krndsource_t source;
} rnd_skew __cacheline_aligned;
@@ -426,21 +426,14 @@ rnd_skew_enable(krndsource_t *rs, bool e
}
static void
-rnd_skew_stop_intr(void *arg)
-{
-
- callout_stop(&rnd_skew.callout);
-}
-
-static void
rnd_skew_get(size_t bytes, void *priv)
{
krndsource_t *skewsrcp = priv;
KASSERT(skewsrcp == &rnd_skew.source);
if (RND_ENABLED(skewsrcp)) {
- /* Measure for 30s */
- callout_schedule(&rnd_skew.stop_callout, hz * 30);
+ /* Measure 100 times */
+ rnd_skew.iter = 100;
callout_schedule(&rnd_skew.callout, 1);
}
}
@@ -448,8 +441,6 @@ rnd_skew_get(size_t bytes, void *priv)
static void
rnd_skew_intr(void *arg)
{
- static int flipflop;
-
/*
* Even on systems with seemingly stable clocks, the
* delta-time entropy estimator seems to think we get 1 bit here
@@ -457,14 +448,15 @@ rnd_skew_intr(void *arg)
*
*/
mutex_spin_enter(&rnd_skew.lock);
- flipflop = !flipflop;
if (RND_ENABLED(&rnd_skew.source)) {
- if (flipflop) {
+ int next_ticks = 1;
+ if (rnd_skew.iter & 1) {
rnd_add_uint32(&rnd_skew.source, rnd_counter());
- callout_schedule(&rnd_skew.callout, hz / 10);
- } else {
- callout_schedule(&rnd_skew.callout, 1);
+ next_ticks = hz / 10;
+ }
+ if (--rnd_skew.iter > 0) {
+ callout_schedule(&rnd_skew.callout, next_ticks);
}
}
mutex_spin_exit(&rnd_skew.lock);
@@ -559,14 +551,13 @@ rnd_init(void)
/* IPL_VM because taken while rnd_global.lock is held. */
mutex_init(&rnd_skew.lock, MUTEX_DEFAULT, IPL_VM);
callout_init(&rnd_skew.callout, CALLOUT_MPSAFE);
- callout_init(&rnd_skew.stop_callout, CALLOUT_MPSAFE);
callout_setfunc(&rnd_skew.callout, rnd_skew_intr, NULL);
- callout_setfunc(&rnd_skew.stop_callout, rnd_skew_stop_intr, NULL);
rndsource_setcb(&rnd_skew.source, rnd_skew_get, &rnd_skew.source);
rndsource_setenable(&rnd_skew.source, rnd_skew_enable);
rnd_attach_source(&rnd_skew.source, "callout", RND_TYPE_SKEW,
RND_FLAG_COLLECT_VALUE|RND_FLAG_ESTIMATE_VALUE|
RND_FLAG_HASCB|RND_FLAG_HASENABLE);
+ rnd_skew.iter = 100;
rnd_skew_intr(NULL);
#endif
