[PATCH] sched/arm64: store cpu topology before notify_cpu_starting

Cheng Jian
2020-04-01T11:28:01Z

when SCHED_CORE enabled, sched_cpu_starting() uses thread_sibling as
SMT_MASK to initialize rq->core, but only after store_cpu_topology(),
the thread_sibling is ready for use.

notify_cpu_starting()
-> sched_cpu_starting() # use thread_sibling

store_cpu_topology(cpu)
-> update_siblings_masks # set thread_sibling

Fix this by doing notify_cpu_starting later, just like x86 do.

Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
---
arch/arm64/kernel/smp.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 5407bf5d98ac..a427c14e82af 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -236,13 +236,18 @@ asmlinkage notrace void secondary_start_kernel(void)
cpuinfo_store_cpu();

/*
- * Enable GIC and timers.
+ * Store cpu topology before notify_cpu_starting,
+ * CPUHP_AP_SCHED_STARTING requires SMT topology
+ * been initialized for SCHED_CORE.
*/
- notify_cpu_starting(cpu);
-
store_cpu_topology(cpu);
numa_add_cpu(cpu);

+ /*
+ * Enable GIC and timers.
+ */
+ notify_cpu_starting(cpu);
+
/*
* OK, now it's safe to let the boot CPU continue. Wait for
* the CPU migration code to notice that the CPU is online
--
2.17.1