[RFC PATCH 4/4] Split cpudl_set() into cpudl_set() and cpudl_clear(). These 2 exercise independent code paths and need different arguments.

From: Tommaso Cucinotta
Date: Thu May 19 2016 - 12:03:03 EST


---
kernel/sched/cpudeadline.c | 71 +++++++++++++++++++++++++++++-----------------
kernel/sched/cpudeadline.h | 3 +-
kernel/sched/deadline.c | 10 +++----
3 files changed, 52 insertions(+), 32 deletions(-)

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 60f933a..0f276bf 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -147,16 +147,15 @@ 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;
@@ -164,17 +163,16 @@ 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) {
+ 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 {
/* 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;
- }
cp->size--;
cp->elements[cpu].idx = IDX_INVALID;
if (old_idx != cp->size) {
@@ -184,24 +182,45 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
cp->elements[new_cpu].idx = old_idx;
cpudl_heapify(cp, old_idx);
}
-
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 sz1 = cp->size++;
+ cp->elements[sz1].dl = dl;
+ cp->elements[sz1].cpu = cpu;
+ cp->elements[cpu].idx = sz1;
+ cpudl_heapify_up(cp, sz1);
+
+ cpumask_clear_cpu(cpu, cp->free_cpus);
} else {
- if (old_idx == IDX_INVALID) {
- int size1 = cp->size++;
- cp->elements[size1].dl = dl;
- cp->elements[size1].cpu = cpu;
- cp->elements[cpu].idx = size1;
- cpudl_heapify_up(cp, size1);
-
- cpumask_clear_cpu(cpu, cp->free_cpus);
- } else {
- cp->elements[old_idx].dl = dl;
- cpudl_heapify(cp, old_idx);
- }
+ cp->elements[old_idx].dl = dl;
+ 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 fcb7f02..f2e8f47 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -795,7 +795,7 @@ 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);
}
}

@@ -810,14 +810,14 @@ 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);
}
}

@@ -1668,7 +1668,7 @@ 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 */
@@ -1677,7 +1677,7 @@ 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