| Date | Sat, 18 Sep 2010 11:58:39 -0700 | From | Greg KH <> | Subject | [075/123] sched: Use rcu in sched_get_rr_param() |
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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; }
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