[RFC PATCH 3/3] sched/deadline: split cpudl_set() into cpudl_set() and cpudl_clear()

[Tommaso Cucinotta]

These 2 exercise independent code paths and need different arguments.
After this change, you call
  cpudl_clear(cp, cpu)
  cpudl_set(cp, cpu, dl)
instead of
  cpudl_set(cp, cpu, 0 /* dl */, 0 /* is_valid */)
  cpudl_set(cp, cpu, dl, 1 /* is_valid */)
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxx>
Cc: Luca Abeni <luca.abeni@xxxxxxxx>
Reviewed-by: Luca Abeni <luca.abeni@xxxxxxxx>
Reviewed-by: Juri Lelli <juri.lelli@xxxxxxx>
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@xxxxxxxx>
---
 kernel/sched/cpudeadline.c | 49 +++++++++++++++++++++++++++++++---------------
 kernel/sched/cpudeadline.h |  3 ++-
 kernel/sched/deadline.c    | 10 +++++-----
 3 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 0ace75a..e731190 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -145,16 +145,15 @@ out:
 }
 
 /*
- * cpudl_set - update the cpudl max-heap
+ * cpudl_clear - remove a cpu from the cpudl max-heap
  * @cp: the cpudl max-heap context
  * @cpu: the target cpu
- * @dl: the new earliest deadline for this cpu
  *
  * Notes: assumes cpu_rq(cpu)->lock is locked
  *
  * Returns: (void)
  */
-void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
+void cpudl_clear(struct cpudl *cp, int cpu)
 {
 	int old_idx, new_cpu;
 	unsigned long flags;
@@ -162,17 +161,15 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
 	WARN_ON(!cpu_present(cpu));
 
 	raw_spin_lock_irqsave(&cp->lock, flags);
+
 	old_idx = cp->elements[cpu].idx;
-	if (!is_valid) {
-		/* remove item */
-		if (old_idx == IDX_INVALID) {
-			/*
-			 * Nothing to remove if old_idx was invalid.
-			 * This could happen if a rq_offline_dl is
-			 * called for a CPU without -dl tasks running.
-			 */
-			goto out;
-		}
+	if (old_idx == IDX_INVALID) {
+		/*
+		 * Nothing to remove if old_idx was invalid.
+		 * This could happen if a rq_offline_dl is
+		 * called for a CPU without -dl tasks running.
+		 */
+	} else {
 		new_cpu = cp->elements[cp->size - 1].cpu;
 		cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
 		cp->elements[old_idx].cpu = new_cpu;
@@ -180,11 +177,32 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
 		cp->elements[new_cpu].idx = old_idx;
 		cp->elements[cpu].idx = IDX_INVALID;
 		cpudl_heapify(cp, old_idx);
-		cpumask_set_cpu(cpu, cp->free_cpus);
 
-		goto out;
+		cpumask_set_cpu(cpu, cp->free_cpus);
 	}
+	raw_spin_unlock_irqrestore(&cp->lock, flags);
+}
+
+/*
+ * cpudl_set - update the cpudl max-heap
+ * @cp: the cpudl max-heap context
+ * @cpu: the target cpu
+ * @dl: the new earliest deadline for this cpu
+ *
+ * Notes: assumes cpu_rq(cpu)->lock is locked
+ *
+ * Returns: (void)
+ */
+void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
+{
+	int old_idx;
+	unsigned long flags;
+
+	WARN_ON(!cpu_present(cpu));
 
+	raw_spin_lock_irqsave(&cp->lock, flags);
+
+	old_idx = cp->elements[cpu].idx;
 	if (old_idx == IDX_INVALID) {
 		int new_idx = cp->size++;
 		cp->elements[new_idx].dl = dl;
@@ -197,7 +215,6 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
 		cpudl_heapify(cp, old_idx);
 	}
 
-out:
 	raw_spin_unlock_irqrestore(&cp->lock, flags);
 }
 
diff --git a/kernel/sched/cpudeadline.h b/kernel/sched/cpudeadline.h
index fcbdf83..f7da8c5 100644
--- a/kernel/sched/cpudeadline.h
+++ b/kernel/sched/cpudeadline.h
@@ -23,7 +23,8 @@ struct cpudl {
 #ifdef CONFIG_SMP
 int cpudl_find(struct cpudl *cp, struct task_struct *p,
 	       struct cpumask *later_mask);
-void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid);
+void cpudl_set(struct cpudl *cp, int cpu, u64 dl);
+void cpudl_clear(struct cpudl *cp, int cpu);
 int cpudl_init(struct cpudl *cp);
 void cpudl_set_freecpu(struct cpudl *cp, int cpu);
 void cpudl_clear_freecpu(struct cpudl *cp, int cpu);
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index d091f4a..18fb0b8 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -798,7 +798,7 @@ static void inc_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
 	if (dl_rq->earliest_dl.curr == 0 ||
 	    dl_time_before(deadline, dl_rq->earliest_dl.curr)) {
 		dl_rq->earliest_dl.curr = deadline;
-		cpudl_set(&rq->rd->cpudl, rq->cpu, deadline, 1);
+		cpudl_set(&rq->rd->cpudl, rq->cpu, deadline);
 	}
 }
 
@@ -813,14 +813,14 @@ static void dec_dl_deadline(struct dl_rq *dl_rq, u64 deadline)
 	if (!dl_rq->dl_nr_running) {
 		dl_rq->earliest_dl.curr = 0;
 		dl_rq->earliest_dl.next = 0;
-		cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
+		cpudl_clear(&rq->rd->cpudl, rq->cpu);
 	} else {
 		struct rb_node *leftmost = dl_rq->rb_leftmost;
 		struct sched_dl_entity *entry;
 
 		entry = rb_entry(leftmost, struct sched_dl_entity, rb_node);
 		dl_rq->earliest_dl.curr = entry->deadline;
-		cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline, 1);
+		cpudl_set(&rq->rd->cpudl, rq->cpu, entry->deadline);
 	}
 }
 
@@ -1671,7 +1671,7 @@ static void rq_online_dl(struct rq *rq)
 
 	cpudl_set_freecpu(&rq->rd->cpudl, rq->cpu);
 	if (rq->dl.dl_nr_running > 0)
-		cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr, 1);
+		cpudl_set(&rq->rd->cpudl, rq->cpu, rq->dl.earliest_dl.curr);
 }
 
 /* Assumes rq->lock is held */
@@ -1680,7 +1680,7 @@ static void rq_offline_dl(struct rq *rq)
 	if (rq->dl.overloaded)
 		dl_clear_overload(rq);
 
-	cpudl_set(&rq->rd->cpudl, rq->cpu, 0, 0);
+	cpudl_clear(&rq->rd->cpudl, rq->cpu);
 	cpudl_clear_freecpu(&rq->rd->cpudl, rq->cpu);
 }
 
-- 
2.7.4