[RESEND PATCH 1/2] sched/isolation: Use raw_smp_processor_id() in housekeeping_any_cpu()

From: Nicolas Saenz Julienne
Date: Mon Feb 28 2022 - 09:16:24 EST


housekeeping_any_cpu() will return a housekeeping CPU. That's it. It'll
try to optimize for NUMA locality and to use the local CPU when
possible, but it's not a requisite.

So let's use raw_smp_processor_id() instead of its vanilla counterpart
in order to allow users to query for housekeeping CPUs without having to
disable preemption.

Signed-off-by: Nicolas Saenz Julienne <nsaenzju@xxxxxxxxxx>
---

NOTE: Resent as I forgot to CC the linux mailing list.

include/linux/sched/isolation.h | 2 +-
kernel/sched/isolation.c | 5 +++--
2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 8c15abd67aed..0c09ff1e4599 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -31,7 +31,7 @@ extern void __init housekeeping_init(void);

static inline int housekeeping_any_cpu(enum hk_type type)
{
- return smp_processor_id();
+ return raw_smp_processor_id();
}

static inline const struct cpumask *housekeeping_cpumask(enum hk_type type)
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index b4d10815c45a..3b8e1d47bbc0 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -43,14 +43,15 @@ int housekeeping_any_cpu(enum hk_type type)

if (static_branch_unlikely(&housekeeping_overridden)) {
if (housekeeping.flags & BIT(type)) {
- cpu = sched_numa_find_closest(housekeeping.cpumasks[type], smp_processor_id());
+ cpu = sched_numa_find_closest(housekeeping.cpumasks[type],
+ raw_smp_processor_id());
if (cpu < nr_cpu_ids)
return cpu;

return cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask);
}
}
- return smp_processor_id();
+ return raw_smp_processor_id();
}
EXPORT_SYMBOL_GPL(housekeeping_any_cpu);

--
2.35.1