[RFC PATCH 5/9] sched: move task rq locking functions to sched.h

[Josh Poimboeuf]

Move task_rq_lock/unlock() to sched.h so they can be used elsewhere.
The livepatch code needs to lock each task's rq in order to safely
examine its stack and switch it to a new patch universe.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 kernel/sched/core.c  | 32 --------------------------------
 kernel/sched/sched.h | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 32 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b5797b7..78d91e6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -326,44 +326,12 @@ static inline struct rq *__task_rq_lock(struct task_struct *p)
 	}
 }
 
-/*
- * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
- */
-static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
-	__acquires(p->pi_lock)
-	__acquires(rq->lock)
-{
-	struct rq *rq;
-
-	for (;;) {
-		raw_spin_lock_irqsave(&p->pi_lock, *flags);
-		rq = task_rq(p);
-		raw_spin_lock(&rq->lock);
-		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p)))
-			return rq;
-		raw_spin_unlock(&rq->lock);
-		raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
-
-		while (unlikely(task_on_rq_migrating(p)))
-			cpu_relax();
-	}
-}
-
 static void __task_rq_unlock(struct rq *rq)
 	__releases(rq->lock)
 {
 	raw_spin_unlock(&rq->lock);
 }
 
-static inline void
-task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
-	__releases(rq->lock)
-	__releases(p->pi_lock)
-{
-	raw_spin_unlock(&rq->lock);
-	raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
-}
-
 /*
  * this_rq_lock - lock this runqueue and disable interrupts.
  */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 9a2a45c..ae514c9 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1542,6 +1542,39 @@ static inline void double_rq_unlock(struct rq *rq1, struct rq *rq2)
 
 #endif
 
+/*
+ * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
+ */
+static inline struct rq *task_rq_lock(struct task_struct *p,
+				      unsigned long *flags)
+	__acquires(p->pi_lock)
+	__acquires(rq->lock)
+{
+	struct rq *rq;
+
+	for (;;) {
+		raw_spin_lock_irqsave(&p->pi_lock, *flags);
+		rq = task_rq(p);
+		raw_spin_lock(&rq->lock);
+		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p)))
+			return rq;
+		raw_spin_unlock(&rq->lock);
+		raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
+
+		while (unlikely(task_on_rq_migrating(p)))
+			cpu_relax();
+	}
+}
+
+static inline void task_rq_unlock(struct rq *rq, struct task_struct *p,
+				  unsigned long *flags)
+	__releases(rq->lock)
+	__releases(p->pi_lock)
+{
+	raw_spin_unlock(&rq->lock);
+	raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
+}
+
 extern struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq);
 extern struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq);
 extern void print_cfs_stats(struct seq_file *m, int cpu);
-- 
2.1.0

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