lkml.org 
[lkml]   [2010]   [Sep]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[075/123] sched: Use rcu in sched_get_rr_param()
From: Thomas Gleixner <tglx@linutronix.de>

commit 1a551ae715825bb2a2107a2dd68de024a1fa4e32 upstream

read_lock(&tasklist_lock) does not protect
sys_sched_get_rr_param() against a concurrent update of the
policy or scheduler parameters as do_sched_scheduler() does not
take the tasklist_lock.

The access to task->sched_class->get_rr_interval is protected by
task_rq_lock(task).

Use rcu_read_lock() to protect find_task_by_vpid() and prevent
the task struct from going away.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091209100706.862897167@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
kernel/sched.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6924,7 +6924,7 @@ SYSCALL_DEFINE2(sched_rr_get_interval, p
return -EINVAL;

retval = -ESRCH;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
p = find_process_by_pid(pid);
if (!p)
goto out_unlock;
@@ -6937,13 +6937,13 @@ SYSCALL_DEFINE2(sched_rr_get_interval, p
time_slice = p->sched_class->get_rr_interval(rq, p);
task_rq_unlock(rq, &flags);

- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
jiffies_to_timespec(time_slice, &t);
retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
return retval;

out_unlock:
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return retval;
}




\
 
 \ /
  Last update: 2010-09-18 21:47    [W:0.239 / U:0.708 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site