sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update

Currently dl tasks will actually return at the very beginning
of rt_mutex_adjust_prio_chain() in !detect_deadlock cases:

    if (waiter->prio == task->prio) {
        if (!detect_deadlock)
            goto out_unlock_pi; // out here
        else
            requeue = false;
    }

As the deadline value of blocked deadline tasks(waiters) without
changing their sched_class(thus prio doesn't change) never changes,
this seems reasonable, but it actually misses the chance of updating
rt_mutex_waiter's "dl_runtime(period)_copy" if a waiter updates its
deadline parameters(dl_runtime, dl_period) or boosted waiter changes
to !deadline class.

Thus, force deadline task not out by adding the !dl_prio() condition.

Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/1460633827-345-7-git-send-email-xlpang@redhat.com
Link: http://lkml.kernel.org/r/20170323150216.206577901@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index bc05b104eaed32768195b5537924303246a192f4..8faf472c430f927309f18460aed14cd2e14be3bc 100644 (file)
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -605,7 +605,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
         * enabled we continue, but stop the requeueing in the chain
         * walk.
         */
-       if (waiter->prio == task->prio) {
+       if (waiter->prio == task->prio && !dl_task(task)) {
                if (!detect_deadlock)
                        goto out_unlock_pi;
                else