random: Mix cputime from each thread that exits to the pool

When a thread exits mix it's cputime (userspace + kernelspace) to the entropy pool.

We don't know how "random" this is, so we use add_device_randomness that doesn't mess
with entropy count.

Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Nick Kossifidis 2012-12-16 22:18:11 -05:00 committed by Theodore Ts'o
parent ec8f02da9e
commit 6133705494
1 changed files with 3 additions and 0 deletions

View File

@ -9,6 +9,7 @@
#include <asm/uaccess.h>
#include <linux/kernel_stat.h>
#include <trace/events/timer.h>
#include <linux/random.h>
/*
* Called after updating RLIMIT_CPU to run cpu timer and update
@ -494,6 +495,8 @@ static void cleanup_timers(struct list_head *head,
*/
void posix_cpu_timers_exit(struct task_struct *tsk)
{
add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
sizeof(unsigned long long));
cleanup_timers(tsk->cpu_timers,
tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);