Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c17ac85504efec5f3a9b0c5b05bffd6f30e5b655 Commit: c17ac85504efec5f3a9b0c5b05bffd6f30e5b655 Parent: b2d9323d139f5c384fa1ef1d74773b4db1c09b3d Author: Paul E. McKenney <[EMAIL PROTECTED]> AuthorDate: Tue Oct 16 23:27:19 2007 -0700 Committer: Linus Torvalds <[EMAIL PROTECTED]> CommitDate: Wed Oct 17 08:42:53 2007 -0700
Make rcutorture RNG use temporal entropy 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. [EMAIL PROTECTED]: Use raw_smp_processor_id() in rcu_random()] Signed-off-by: Paul E. McKenney <[EMAIL PROTECTED]> Cc: Ingo Molnar <[EMAIL PROTECTED]> Signed-off-by: Gautham R Shenoy <[EMAIL PROTECTED]> Signed-off-by: Andrew Morton <[EMAIL PROTECTED]> Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]> --- kernel/rcutorture.c | 9 +++------ 1 files changed, 3 insertions(+), 6 deletions(-) diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index dd413bf..c3e165c 100644 --- a/kernel/rcutorture.c +++ b/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; - To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html