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

Josh Poimboeuf
2015-02-09T17:31:34Z

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@redhat.com>
---
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