sched: Wrap rq::lock access

In preparation of playing games with rq->lock, abstract the thing
using an accessor.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Don Hiatt <dhiatt@digitalocean.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123308.136465446@infradead.org

1 files changed, 52 insertions, 53 deletions

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index f65458710635..dbabf282c039 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -905,7 +905,7 @@ DECLARE_STATIC_KEY_FALSE(sched_uclamp_used);
  */
 struct rq {
 	/* runqueue lock: */
-	raw_spinlock_t		lock;
+	raw_spinlock_t		__lock;
 
 	/*
 	 * nr_running and cpu_load should be in the same cacheline because
@@ -1115,7 +1115,7 @@ static inline bool is_migration_disabled(struct task_struct *p)
 
 static inline raw_spinlock_t *rq_lockp(struct rq *rq)
 {
-	return &rq->lock;
+	return &rq->__lock;
 }
 
 static inline void lockdep_assert_rq_held(struct rq *rq)
@@ -1229,7 +1229,7 @@ static inline void assert_clock_updated(struct rq *rq)
 
 static inline u64 rq_clock(struct rq *rq)
 {
-	lockdep_assert_held(&rq->lock);
+	lockdep_assert_rq_held(rq);
 	assert_clock_updated(rq);
 
 	return rq->clock;
@@ -1237,7 +1237,7 @@ static inline u64 rq_clock(struct rq *rq)
 
 static inline u64 rq_clock_task(struct rq *rq)
 {
-	lockdep_assert_held(&rq->lock);
+	lockdep_assert_rq_held(rq);
 	assert_clock_updated(rq);
 
 	return rq->clock_task;
@@ -1263,7 +1263,7 @@ static inline u64 rq_clock_thermal(struct rq *rq)
 
 static inline void rq_clock_skip_update(struct rq *rq)
 {
-	lockdep_assert_held(&rq->lock);
+	lockdep_assert_rq_held(rq);
 	rq->clock_update_flags |= RQCF_REQ_SKIP;
 }
 
@@ -1273,7 +1273,7 @@ static inline void rq_clock_skip_update(struct rq *rq)
  */
 static inline void rq_clock_cancel_skipupdate(struct rq *rq)
 {
-	lockdep_assert_held(&rq->lock);
+	lockdep_assert_rq_held(rq);
 	rq->clock_update_flags &= ~RQCF_REQ_SKIP;
 }
 
@@ -1304,7 +1304,7 @@ extern struct callback_head balance_push_callback;
  */
 static inline void rq_pin_lock(struct rq *rq, struct rq_flags *rf)
 {
-	rf->cookie = lockdep_pin_lock(&rq->lock);
+	rf->cookie = lockdep_pin_lock(rq_lockp(rq));
 
 #ifdef CONFIG_SCHED_DEBUG
 	rq->clock_update_flags &= (RQCF_REQ_SKIP|RQCF_ACT_SKIP);
@@ -1322,12 +1322,12 @@ static inline void rq_unpin_lock(struct rq *rq, struct rq_flags *rf)
 		rf->clock_update_flags = RQCF_UPDATED;
 #endif
 
-	lockdep_unpin_lock(&rq->lock, rf->cookie);
+	lockdep_unpin_lock(rq_lockp(rq), rf->cookie);
 }
 
 static inline void rq_repin_lock(struct rq *rq, struct rq_flags *rf)
 {
-	lockdep_repin_lock(&rq->lock, rf->cookie);
+	lockdep_repin_lock(rq_lockp(rq), rf->cookie);
 
 #ifdef CONFIG_SCHED_DEBUG
 	/*
@@ -1348,7 +1348,7 @@ static inline void __task_rq_unlock(struct rq *rq, struct rq_flags *rf)
 	__releases(rq->lock)
 {
 	rq_unpin_lock(rq, rf);
-	raw_spin_unlock(&rq->lock);
+	raw_spin_rq_unlock(rq);
 }
 
 static inline void
@@ -1357,7 +1357,7 @@ task_rq_unlock(struct rq *rq, struct task_struct *p, struct rq_flags *rf)
 	__releases(p->pi_lock)
 {
 	rq_unpin_lock(rq, rf);
-	raw_spin_unlock(&rq->lock);
+	raw_spin_rq_unlock(rq);
 	raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
 }
 
@@ -1365,7 +1365,7 @@ static inline void
 rq_lock_irqsave(struct rq *rq, struct rq_flags *rf)
 	__acquires(rq->lock)
 {
-	raw_spin_lock_irqsave(&rq->lock, rf->flags);
+	raw_spin_rq_lock_irqsave(rq, rf->flags);
 	rq_pin_lock(rq, rf);
 }
 
@@ -1373,7 +1373,7 @@ static inline void
 rq_lock_irq(struct rq *rq, struct rq_flags *rf)
 	__acquires(rq->lock)
 {
-	raw_spin_lock_irq(&rq->lock);
+	raw_spin_rq_lock_irq(rq);
 	rq_pin_lock(rq, rf);
 }
 
@@ -1381,7 +1381,7 @@ static inline void
 rq_lock(struct rq *rq, struct rq_flags *rf)
 	__acquires(rq->lock)
 {
-	raw_spin_lock(&rq->lock);
+	raw_spin_rq_lock(rq);
 	rq_pin_lock(rq, rf);
 }
 
@@ -1389,7 +1389,7 @@ static inline void
 rq_relock(struct rq *rq, struct rq_flags *rf)
 	__acquires(rq->lock)
 {
-	raw_spin_lock(&rq->lock);
+	raw_spin_rq_lock(rq);
 	rq_repin_lock(rq, rf);
 }
 
@@ -1398,7 +1398,7 @@ rq_unlock_irqrestore(struct rq *rq, struct rq_flags *rf)
 	__releases(rq->lock)
 {
 	rq_unpin_lock(rq, rf);
-	raw_spin_unlock_irqrestore(&rq->lock, rf->flags);
+	raw_spin_rq_unlock_irqrestore(rq, rf->flags);
 }
 
 static inline void
@@ -1406,7 +1406,7 @@ rq_unlock_irq(struct rq *rq, struct rq_flags *rf)
 	__releases(rq->lock)
 {
 	rq_unpin_lock(rq, rf);
-	raw_spin_unlock_irq(&rq->lock);
+	raw_spin_rq_unlock_irq(rq);
 }
 
 static inline void
@@ -1414,7 +1414,7 @@ rq_unlock(struct rq *rq, struct rq_flags *rf)
 	__releases(rq->lock)
 {
 	rq_unpin_lock(rq, rf);
-	raw_spin_unlock(&rq->lock);
+	raw_spin_rq_unlock(rq);
 }
 
 static inline struct rq *
@@ -1479,7 +1479,7 @@ queue_balance_callback(struct rq *rq,
 		       struct callback_head *head,
 		       void (*func)(struct rq *rq))
 {
-	lockdep_assert_held(&rq->lock);
+	lockdep_assert_rq_held(rq);
 
 	if (unlikely(head->next || rq->balance_callback == &balance_push_callback))
 		return;
@@ -2019,7 +2019,7 @@ static inline struct task_struct *get_push_task(struct rq *rq)
 {
 	struct task_struct *p = rq->curr;
 
-	lockdep_assert_held(&rq->lock);
+	lockdep_assert_rq_held(rq);
 
 	if (rq->push_busy)
 		return NULL;
@@ -2249,7 +2249,7 @@ static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
 	__acquires(busiest->lock)
 	__acquires(this_rq->lock)
 {
-	raw_spin_unlock(&this_rq->lock);
+	raw_spin_rq_unlock(this_rq);
 	double_rq_lock(this_rq, busiest);
 
 	return 1;
@@ -2268,20 +2268,22 @@ static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
 	__acquires(busiest->lock)
 	__acquires(this_rq->lock)
 {
-	int ret = 0;
-
-	if (unlikely(!raw_spin_trylock(&busiest->lock))) {
-		if (busiest < this_rq) {
-			raw_spin_unlock(&this_rq->lock);
-			raw_spin_lock(&busiest->lock);
-			raw_spin_lock_nested(&this_rq->lock,
-					      SINGLE_DEPTH_NESTING);
-			ret = 1;
-		} else
-			raw_spin_lock_nested(&busiest->lock,
-					      SINGLE_DEPTH_NESTING);
+	if (rq_lockp(this_rq) == rq_lockp(busiest))
+		return 0;
+
+	if (likely(raw_spin_rq_trylock(busiest)))
+		return 0;
+
+	if (rq_lockp(busiest) >= rq_lockp(this_rq)) {
+		raw_spin_rq_lock_nested(busiest, SINGLE_DEPTH_NESTING);
+		return 0;
 	}
-	return ret;
+
+	raw_spin_rq_unlock(this_rq);
+	raw_spin_rq_lock(busiest);
+	raw_spin_rq_lock_nested(this_rq, SINGLE_DEPTH_NESTING);
+
+	return 1;
 }
 
 #endif /* CONFIG_PREEMPTION */
@@ -2291,11 +2293,7 @@ static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
  */
 static inline int double_lock_balance(struct rq *this_rq, struct rq *busiest)
 {
-	if (unlikely(!irqs_disabled())) {
-		/* printk() doesn't work well under rq->lock */
-		raw_spin_unlock(&this_rq->lock);
-		BUG_ON(1);
-	}
+	lockdep_assert_irqs_disabled();
 
 	return _double_lock_balance(this_rq, busiest);
 }
@@ -2303,8 +2301,9 @@ static inline int double_lock_balance(struct rq *this_rq, struct rq *busiest)
 static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
 	__releases(busiest->lock)
 {
-	raw_spin_unlock(&busiest->lock);
-	lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
+	if (rq_lockp(this_rq) != rq_lockp(busiest))
+		raw_spin_rq_unlock(busiest);
+	lock_set_subclass(&rq_lockp(this_rq)->dep_map, 0, _RET_IP_);
 }
 
 static inline void double_lock(spinlock_t *l1, spinlock_t *l2)
@@ -2345,16 +2344,16 @@ static inline void double_rq_lock(struct rq *rq1, struct rq *rq2)
 	__acquires(rq2->lock)
 {
 	BUG_ON(!irqs_disabled());
-	if (rq1 == rq2) {
-		raw_spin_lock(&rq1->lock);
+	if (rq_lockp(rq1) == rq_lockp(rq2)) {
+		raw_spin_rq_lock(rq1);
 		__acquire(rq2->lock);	/* Fake it out ;) */
 	} else {
-		if (rq1 < rq2) {
-			raw_spin_lock(&rq1->lock);
-			raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
+		if (rq_lockp(rq1) < rq_lockp(rq2)) {
+			raw_spin_rq_lock(rq1);
+			raw_spin_rq_lock_nested(rq2, SINGLE_DEPTH_NESTING);
 		} else {
-			raw_spin_lock(&rq2->lock);
-			raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
+			raw_spin_rq_lock(rq2);
+			raw_spin_rq_lock_nested(rq1, SINGLE_DEPTH_NESTING);
 		}
 	}
 }
@@ -2369,9 +2368,9 @@ static inline void double_rq_unlock(struct rq *rq1, struct rq *rq2)
 	__releases(rq1->lock)
 	__releases(rq2->lock)
 {
-	raw_spin_unlock(&rq1->lock);
-	if (rq1 != rq2)
-		raw_spin_unlock(&rq2->lock);
+	raw_spin_rq_unlock(rq1);
+	if (rq_lockp(rq1) != rq_lockp(rq2))
+		raw_spin_rq_unlock(rq2);
 	else
 		__release(rq2->lock);
 }
@@ -2394,7 +2393,7 @@ static inline void double_rq_lock(struct rq *rq1, struct rq *rq2)
 {
 	BUG_ON(!irqs_disabled());
 	BUG_ON(rq1 != rq2);
-	raw_spin_lock(&rq1->lock);
+	raw_spin_rq_lock(rq1);
 	__acquire(rq2->lock);	/* Fake it out ;) */
 }
 
@@ -2409,7 +2408,7 @@ static inline void double_rq_unlock(struct rq *rq1, struct rq *rq2)
 	__releases(rq2->lock)
 {
 	BUG_ON(rq1 != rq2);
-	raw_spin_unlock(&rq1->lock);
+	raw_spin_rq_unlock(rq1);
 	__release(rq2->lock);
 }