sched/core: Add missing lockdep_unpin() annotations

Luca and Wanpeng reported two missing annotations that led to
false lockdep complaints. Add the missing annotations.

Reported-by: Luca Abeni <luca.abeni@unitn.it>
Reported-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: cbce1a686700 ("sched,lockdep: Employ lock pinning")
Link: http://lkml.kernel.org/r/20151023095008.GY17308@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5bd7d60..bcd214e 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2366,8 +2366,15 @@ void wake_up_new_task(struct task_struct *p)
        trace_sched_wakeup_new(p);
        check_preempt_curr(rq, p, WF_FORK);
 #ifdef CONFIG_SMP
-       if (p->sched_class->task_woken)
+       if (p->sched_class->task_woken) {
+               /*
+                * Nothing relies on rq->lock after this, so its fine to
+                * drop it.
+                */
+               lockdep_unpin_lock(&rq->lock);
                p->sched_class->task_woken(rq, p);
+               lockdep_pin_lock(&rq->lock);
+       }
 #endif
        task_rq_unlock(rq, p, &flags);
 }

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 142df26..8b0a15e 100644 (file)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -668,8 +668,15 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
         * Queueing this task back might have overloaded rq, check if we need
         * to kick someone away.
         */
-       if (has_pushable_dl_tasks(rq))
+       if (has_pushable_dl_tasks(rq)) {
+               /*
+                * Nothing relies on rq->lock after this, so its safe to drop
+                * rq->lock.
+                */
+               lockdep_unpin_lock(&rq->lock);
                push_dl_task(rq);
+               lockdep_pin_lock(&rq->lock);
+       }
 #endif
 
 unlock: