[PATCH v4 03/10] drivers/perf: hisi: Migrate to one online CPU if no associated one online

[Yicong Yang]

From: Yicong Yang <yangyicong at hisilicon.com>

If the selected CPU hisi_pmu::on_cpu goes offline, driver will select
a new online CPU from hisi_pmu::associated_cpus, or if no online CPU
found the PMU context won't be migrated. However for uncore PMUs the
associated CPUs are just a peference and it also works to schedule
the events on any online CPUs. So add a fallback to choose an online
CPU if no associated CPUs found.

Signed-off-by: Yicong Yang <yangyicong at hisilicon.com>
---
 drivers/perf/hisilicon/hisi_uncore_pmu.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/hisilicon/hisi_uncore_pmu.c b/drivers/perf/hisilicon/hisi_uncore_pmu.c
index dbe7299f0f05..3a4db5c5d70f 100644
--- a/drivers/perf/hisilicon/hisi_uncore_pmu.c
+++ b/drivers/perf/hisilicon/hisi_uncore_pmu.c
@@ -499,9 +499,16 @@ int hisi_uncore_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
 	/* Give up ownership of the PMU */
 	hisi_pmu->on_cpu = -1;
 
-	/* Choose a new CPU to migrate ownership of the PMU to */
+	/*
+	 * Migrate ownership of the PMU to a new CPU chosen from PMU's online
+	 * associated CPUs if possible, if no associated CPU online then
+	 * migrate to one online CPU.
+	 */
 	target = cpumask_any_and_but(&hisi_pmu->associated_cpus,
 				     cpu_online_mask, cpu);
+	if (target >= nr_cpu_ids)
+		target = cpumask_any_but(cpu_online_mask, cpu);
+
 	if (target >= nr_cpu_ids)
 		return 0;
 
-- 
2.24.0