From: Thomas Gleixner Date: Wed, 9 Dec 2009 10:15:11 +0000 (+0000) Subject: sched: Use rcu in sched_get_rr_param() X-Git-Tag: v2.6.33-rc2~48^2~21 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1a551ae715825bb2a2107a2dd68de024a1fa4e32;p=karo-tx-linux.git sched: Use rcu in sched_get_rr_param() 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 Cc: Peter Zijlstra LKML-Reference: <20091209100706.862897167@linutronix.de> Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched.c b/kernel/sched.c index 79893123325c..db5c26692dd5 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6873,7 +6873,7 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, return -EINVAL; retval = -ESRCH; - read_lock(&tasklist_lock); + rcu_read_lock(); p = find_process_by_pid(pid); if (!p) goto out_unlock; @@ -6886,13 +6886,13 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid, 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; }