prctl: adds PR_SET_TIMERSLACK_PID for setting timer slack of an arbitrary thread.
Second argument is similar to PR_SET_TIMERSLACK, if non-zero then the
slack is set to that value otherwise sets it to the default for the thread.
Takes PID of the thread as the third argument.
This allows power/performance management software to set timer slack for
other threads according to its policy for the thread (such as when the
thread is designated foreground vs. background activity)
Change-Id: I744d451ff4e60dae69f38f53948ff36c51c14a3f
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
diff --git a/kernel/sys.c b/kernel/sys.c
index 89d5be4..5703437 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2076,6 +2076,7 @@
unsigned long, arg4, unsigned long, arg5)
{
struct task_struct *me = current;
+ struct task_struct *tsk;
unsigned char comm[sizeof(me->comm)];
long error;
@@ -2202,6 +2203,23 @@
else
return -EINVAL;
break;
+ case PR_SET_TIMERSLACK_PID:
+ rcu_read_lock();
+ tsk = find_task_by_pid_ns((pid_t)arg3, &init_pid_ns);
+ if (tsk == NULL) {
+ rcu_read_unlock();
+ return -EINVAL;
+ }
+ get_task_struct(tsk);
+ rcu_read_unlock();
+ if (arg2 <= 0)
+ tsk->timer_slack_ns =
+ tsk->default_timer_slack_ns;
+ else
+ tsk->timer_slack_ns = arg2;
+ put_task_struct(tsk);
+ error = 0;
+ break;
default:
return -EINVAL;
}