[PATCH v2 02/12] sched/core: Introduce rq_drop_lock()

[Peter Zijlstra <peterz@infradead.org>]

Currently rq_unpin_lock() serves a dual purpose, it pairs with both
rq_pin_lock() and rq_repin_lock(). That is:

	rq_pin_lock()
	  rq_unpin_lock()
          rq_repin_lock()
	rq_unpin_lock()

In prepration of making the temporary drop and the final drop
distinct, this needs another function. Introduce and use
rq_drop_lock() for the temporary drop, like:

	rq_pin_lock()
	  rq_drop_lock()
          rq_repin_lock()
	rq_unpin_lock()

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/sched/core.c     |    8 ++++----
 kernel/sched/deadline.c |    4 ++--
 kernel/sched/ext/ext.c  |    4 ++--
 kernel/sched/fair.c     |    2 +-
 kernel/sched/rt.c       |    2 +-
 kernel/sched/sched.h    |    5 +++++
 6 files changed, 15 insertions(+), 10 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3910,7 +3910,7 @@ ttwu_do_activate(struct rq *rq, struct t
 		 * Our task @p is fully woken up and running; so it's safe to
 		 * drop the rq->lock, hereafter rq is only used for statistics.
 		 */
-		rq_unpin_lock(rq, rf);
+		rq_drop_lock(rq, rf);
 		p->sched_class->task_woken(rq, p);
 		rq_repin_lock(rq, rf);
 	}
@@ -5042,7 +5042,7 @@ void wake_up_new_task(struct task_struct
 		 * Nothing relies on rq->lock after this, so it's fine to
 		 * drop it.
 		 */
-		rq_unpin_lock(rq, &rf);
+		rq_drop_lock(rq, &rf);
 		p->sched_class->task_woken(rq, p);
 		rq_repin_lock(rq, &rf);
 	}
@@ -5260,7 +5260,7 @@ struct balance_callback *splice_balance_
 void __balance_callbacks(struct rq *rq, struct rq_flags *rf)
 {
 	if (rf)
-		rq_unpin_lock(rq, rf);
+		rq_drop_lock(rq, rf);
 	do_balance_callbacks(rq, __splice_balance_callbacks(rq, false));
 	if (rf)
 		rq_repin_lock(rq, rf);
@@ -6929,7 +6929,7 @@ static inline void proxy_release_rq_lock
 	 * to pick_again, so the callbacks will get re-established.
 	 */
 	zap_balance_callbacks(rq);
-	rq_unpin_lock(rq, rf);
+	rq_drop_lock(rq, rf);
 	raw_spin_rq_unlock(rq);
 }
 
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1129,7 +1129,7 @@ static void __push_dl_task(struct rq *rq
 		 * Nothing relies on rq->lock after this, so its safe to drop
 		 * rq->lock.
 		 */
-		rq_unpin_lock(rq, rf);
+		rq_drop_lock(rq, rf);
 		push_dl_task(rq);
 		rq_repin_lock(rq, rf);
 	}
@@ -2720,7 +2720,7 @@ static int balance_dl(struct rq *rq, str
 		 * disabled avoiding further scheduler activity on it and we've
 		 * not yet started the picking loop.
 		 */
-		rq_unpin_lock(rq, rf);
+		rq_drop_lock(rq, rf);
 		pull_dl_task(rq);
 		rq_repin_lock(rq, rf);
 	}
--- a/kernel/sched/ext/ext.c
+++ b/kernel/sched/ext/ext.c
@@ -3924,7 +3924,7 @@ static enum scx_dsp_verdict dispatch_pic
 {
 	enum scx_dsp_verdict verdict;
 
-	rq_unpin_lock(rq, rf);
+	rq_drop_lock(rq, rf);
 	verdict = dispatch_one(rq, prev);
 	rq_repin_lock(rq, rf);
 
@@ -3949,7 +3949,7 @@ static enum scx_dsp_verdict dispatch_cor
 	if (rq->scx.flags & SCX_RQ_IN_DISPATCH)
 		return SCX_DSP_NONE;
 
-	rq_unpin_lock(rq, rf);
+	rq_drop_lock(rq, rf);
 
 	verdict = dispatch_one(rq, prev);
 
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -14907,7 +14907,7 @@ static int sched_balance_newidle(struct
 	 * further scheduler activity on it and we're being very careful to
 	 * re-start the picking loop.
 	 */
-	rq_unpin_lock(this_rq, rf);
+	rq_drop_lock(this_rq, rf);
 
 	sd = rcu_dereference_sched_domain(this_rq->sd);
 	if (!sd)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1611,7 +1611,7 @@ static int balance_rt(struct rq *rq, str
 		 * disabled avoiding further scheduler activity on it and we've
 		 * not yet started the picking loop.
 		 */
-		rq_unpin_lock(rq, rf);
+		rq_drop_lock(rq, rf);
 		pull_rt_task(rq);
 		rq_repin_lock(rq, rf);
 	}
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1991,6 +1991,11 @@ static inline void rq_unpin_lock(struct
 	lockdep_unpin_lock(__rq_lockp(rq), rf->cookie);
 }
 
+static inline void rq_drop_lock(struct rq *rq, struct rq_flags *rf)
+{
+	rq_unpin_lock(rq, rf);
+}
+
 static inline void rq_repin_lock(struct rq *rq, struct rq_flags *rf)
 {
 	lockdep_repin_lock(__rq_lockp(rq), rf->cookie);