!1186 Fix NULL pointer and Keep PERF_PMU_CAP_EXCLUSIVE

Merge Pull Request from: @ci-robot 
 
PR sync from: Junhao He <hejunhao3@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/SFPID77Q7WRTZVPTFE5WSEDPJADFTQAY/ 
1) Fix NULL pointer for hisi_ptt
2) Keep to advertise PERF_PMU_CAP_EXCLUSIVE. Such ptt pmus can
   only have one event scheduled at a time.

Junhao He (2):
  hwtracing: hisi_ptt: Add dummy callback pmu::read()
  hwtracing: hisi_ptt: Keep to advertise PERF_PMU_CAP_EXCLUSIVE


-- 
2.33.0
 
 
Link:https://gitee.com/openeuler/kernel/pulls/1186 

Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> 

drivers/hwtracing/ptt/hisi_ptt.c

@@ -1178,6 +1178,10 @@ static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
 	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
 }
 
+static void hisi_ptt_pmu_read(struct perf_event *event)
+{
+}
+
 static void hisi_ptt_remove_cpuhp_instance(void *hotplug_node)
 {
 	cpuhp_state_remove_instance_nocalls(hisi_ptt_pmu_online, hotplug_node);
@@ -1211,7 +1215,7 @@ static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
 
 	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
 		.module		= THIS_MODULE,
-		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
+		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE | PERF_PMU_CAP_EXCLUSIVE,
 		.task_ctx_nr	= perf_sw_context,
 		.attr_groups	= hisi_ptt_pmu_groups,
 		.event_init	= hisi_ptt_pmu_event_init,
@@ -1221,6 +1225,7 @@ static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
 		.stop		= hisi_ptt_pmu_stop,
 		.add		= hisi_ptt_pmu_add,
 		.del		= hisi_ptt_pmu_del,
+		.read		= hisi_ptt_pmu_read,
 	};
 
 	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);