linux-kernel - [PATCH 1/2] sched: Move __task_rq_{, un}lock() to kernel/sched/sched.h

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Date:	Tue, 17 Feb 2015 13:46:51 +0300
From:	Kirill Tkhai <ktkhai@...allels.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH 1/2] sched: Move __task_rq_{, un}lock() to
 kernel/sched/sched.h


Place it in sched.h, because dl_task_timer() needs it.
Also remove lockdep check, which is not fit to this
function.

Similar to idea of Josh Poimboeuf for task_rq_{,un}lock():
https://lkml.org/lkml/2015/2/9/476

Signed-off-by: Kirill Tkhai <ktkhai@...allels.com>
CC: Josh Poimboeuf <jpoimboe@...hat.com>
---
 kernel/sched/core.c     |   28 ----------------------------
 kernel/sched/deadline.c |   12 +++---------
 kernel/sched/sched.h    |   26 ++++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 37 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0466e61..fc12a1d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -307,28 +307,6 @@ __read_mostly int scheduler_running;
 int sysctl_sched_rt_runtime = 950000;
 
 /*
- * __task_rq_lock - lock the rq @p resides on.
- */
-static inline struct rq *__task_rq_lock(struct task_struct *p)
-	__acquires(rq->lock)
-{
-	struct rq *rq;
-
-	lockdep_assert_held(&p->pi_lock);
-
-	for (;;) {
-		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);
-
-		while (unlikely(task_on_rq_migrating(p)))
-			cpu_relax();
-	}
-}
-
-/*
  * 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)
@@ -351,12 +329,6 @@ static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
 	}
 }
 
-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)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 29ae704..e008b51 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -512,14 +512,8 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
 						     dl_timer);
 	struct task_struct *p = dl_task_of(dl_se);
 	struct rq *rq;
-again:
-	rq = task_rq(p);
-	raw_spin_lock(&rq->lock);
-	if (rq != task_rq(p) || task_on_rq_migrating(p)) {
-		/* Task was move{d,ing}, retry */
-		raw_spin_unlock(&rq->lock);
-		goto again;
-	}
+
+	rq = __task_rq_lock(p);
 
 	/*
 	 * We need to take care of several possible races here:
@@ -574,7 +568,7 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
 		push_dl_task(rq);
 #endif
 unlock:
-	raw_spin_unlock(&rq->lock);
+	__task_rq_unlock(rq);
 
 	return HRTIMER_NORESTART;
 }
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 0870db2..f65f57c 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1020,6 +1020,32 @@ static inline int task_on_rq_migrating(struct task_struct *p)
 	return p->on_rq == TASK_ON_RQ_MIGRATING;
 }
 
+/*
+ * __task_rq_lock - lock the rq @p resides on.
+ */
+static inline struct rq *__task_rq_lock(struct task_struct *p)
+	__acquires(rq->lock)
+{
+	struct rq *rq;
+
+	for (;;) {
+		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);
+
+		while (unlikely(task_on_rq_migrating(p)))
+			cpu_relax();
+	}
+}
+
+static inline void __task_rq_unlock(struct rq *rq)
+	__releases(rq->lock)
+{
+	raw_spin_unlock(&rq->lock);
+}
+
 #ifndef prepare_arch_switch
 # define prepare_arch_switch(next)	do { } while (0)
 #endif



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