sched,lockdep: Employ lock pinning

Employ the new lockdep lock pinning annotation to ensure no
'accidental' lock-breaks happen with rq->lock.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: ktkhai@parallels.com
Cc: rostedt@goodmis.org
Cc: juri.lelli@gmail.com
Cc: pang.xunlei@linaro.org
Cc: oleg@redhat.com
Cc: wanpeng.li@linux.intel.com
Cc: umgwanakikbuti@gmail.com
Link: http://lkml.kernel.org/r/20150611124744.003233193@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 8 insertions, 2 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 62949ab06bc2..ef02d11654cd 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1439,8 +1439,10 @@ static inline struct rq *__task_rq_lock(struct task_struct *p)
         for (;;) {
                 rq = task_rq(p);
                 raw_spin_lock(&rq->lock);
-                if (likely(rq == task_rq(p) && !task_on_rq_migrating(p)))
+                if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
+                        lockdep_pin_lock(&rq->lock);
                         return rq;
+                }
                 raw_spin_unlock(&rq->lock);
 
                 while (unlikely(task_on_rq_migrating(p)))
@@ -1477,8 +1479,10 @@ static inline struct rq *task_rq_lock(struct task_struct *p, unsigned long *flag
                  * If we observe the new cpu in task_rq_lock, the acquire will
                  * pair with the WMB to ensure we must then also see migrating.
                  */
-                if (likely(rq == task_rq(p) && !task_on_rq_migrating(p)))
+                if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
+                        lockdep_pin_lock(&rq->lock);
                         return rq;
+                }
                 raw_spin_unlock(&rq->lock);
                 raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 
@@ -1490,6 +1494,7 @@ static inline struct rq *task_rq_lock(struct task_struct *p, unsigned long *flag
 static inline void __task_rq_unlock(struct rq *rq)
         __releases(rq->lock)
 {
+        lockdep_unpin_lock(&rq->lock);
         raw_spin_unlock(&rq->lock);
 }
 
@@ -1498,6 +1503,7 @@ task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
         __releases(rq->lock)
         __releases(p->pi_lock)
 {
+        lockdep_unpin_lock(&rq->lock);
         raw_spin_unlock(&rq->lock);
         raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 }