The patch titled
Make rcutorture RNG use temporal entropy
has been removed from the -mm tree. Its filename was
make-rcutorture-rng-use-temporal-entropy.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: Make rcutorture RNG use temporal entropy
From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Repost of http://lkml.org/lkml/2007/8/10/472 made available by request.
The locking used by get_random_bytes() can conflict with the
preempt_disable() and synchronize_sched() form of RCU. This patch changes
rcutorture's RNG to gather entropy from the new cpu_clock() interface
(relying on interrupts, preemption, daemons, and rcutorture's reader
thread's rock-bottom scheduling priority to provide useful entropy), and
also adds and EXPORT_SYMBOL_GPL() to make that interface available to GPLed
kernel modules such as rcutorture.
Passes several hours of rcutorture.
[ego@xxxxxxxxxx: Use raw_smp_processor_id() in rcu_random()]
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Gautham R Shenoy <ego@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/rcutorture.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff -puN kernel/rcutorture.c~make-rcutorture-rng-use-temporal-entropy kernel/rcutorture.c
--- a/kernel/rcutorture.c~make-rcutorture-rng-use-temporal-entropy
+++ a/kernel/rcutorture.c
@@ -41,7 +41,6 @@
#include <linux/notifier.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
-#include <linux/random.h>
#include <linux/delay.h>
#include <linux/byteorder/swabb.h>
#include <linux/stat.h>
@@ -165,16 +164,14 @@ struct rcu_random_state {
/*
* Crude but fast random-number generator. Uses a linear congruential
- * generator, with occasional help from get_random_bytes().
+ * generator, with occasional help from cpu_clock().
*/
static unsigned long
rcu_random(struct rcu_random_state *rrsp)
{
- long refresh;
-
if (--rrsp->rrs_count < 0) {
- get_random_bytes(&refresh, sizeof(refresh));
- rrsp->rrs_state += refresh;
+ rrsp->rrs_state +=
+ (unsigned long)cpu_clock(raw_smp_processor_id());
rrsp->rrs_count = RCU_RANDOM_REFRESH;
}
rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
_
Patches currently in -mm which might be from paulmck@xxxxxxxxxxxxxxxxxx are
origin.patch
make-access-to-tasks-nsproxy-lighter.patch
make-access-to-tasks-nsproxy-lighterpatch-breaks-unshare.patch
make-access-to-tasks-nsproxy-lighter-update-get_net_ns_by_pid.patch
-
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