From c365c292d05908c6ea6f32708f331e21033fe71d Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 7 Feb 2014 20:58:42 +0100 Subject: sched: Consider pi boosting in setscheduler() If a PI boosted task policy/priority is modified by a setscheduler() call we unconditionally dequeue and requeue the task if it is on the runqueue even if the new priority is lower than the current effective boosted priority. This can result in undesired reordering of the priority bucket list. If the new priority is less or equal than the current effective we just store the new parameters in the task struct and leave the scheduler class and the runqueue untouched. This is handled when the task deboosts itself. Only if the new priority is higher than the effective boosted priority we apply the change immediately. Signed-off-by: Thomas Gleixner [ Rebase ontop of v3.14-rc1. ] Signed-off-by: Sebastian Andrzej Siewior Cc: Dario Faggioli Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1391803122-4425-7-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar --- kernel/locking/rtmutex.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'kernel/locking') diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 2e960a2bab81..aa4dff04b594 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -212,6 +212,18 @@ struct task_struct *rt_mutex_get_top_task(struct task_struct *task) return task_top_pi_waiter(task)->task; } +/* + * Called by sched_setscheduler() to check whether the priority change + * is overruled by a possible priority boosting. + */ +int rt_mutex_check_prio(struct task_struct *task, int newprio) +{ + if (!task_has_pi_waiters(task)) + return 0; + + return task_top_pi_waiter(task)->task->prio <= newprio; +} + /* * Adjust the priority of a task, after its pi_waiters got modified. * -- cgit v1.2.3