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Subject[PATCH 6/8] sched/deadline: Don't return meaningless cpu in cpudl_maximum_cpu()
Date
When the heap tree is empty, cp->elements[0].cpu has meaningless value.
We need to consider the case.

Signed-off-by: Byungchul Park <byungchul.park@lge.com>
---
kernel/sched/cpudeadline.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 37bbb66..21404b8 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -107,7 +107,8 @@ static void cpudl_heapify(struct cpudl_item *e, int size, int idx)

static inline int cpudl_maximum_cpu(struct cpudl *cp)
{
- return cp->elements[0].cpu;
+ int cpu = cp->elements[0].cpu;
+ return cp->elements[cpu].idx == IDX_INVALID ? -1 : cpu;
}

static inline u64 cpudl_maximum_dl(struct cpudl *cp)
@@ -127,7 +128,8 @@ static int cpudl_fast_find(struct cpudl *cp, struct task_struct *p)
max_dl = cpudl_maximum_dl(cp);
raw_spin_unlock_irqrestore(&cp->lock, flags);

- if (cpumask_test_cpu(max_cpu, &p->cpus_allowed) &&
+ if (max_cpu != -1 &&
+ cpumask_test_cpu(max_cpu, &p->cpus_allowed) &&
dl_time_before(dl_se->deadline, max_dl))
return max_cpu;

--
1.9.1
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