[PATCH 1/2] drivers/nvdimm: Fix build failure when CONFIG_PERF_EVENTS is not set

[Kajol Jain]

The following build failure occures when CONFIG_PERF_EVENTS is not set
as generic pmu functions are not visible in that scenario.

|-- s390-randconfig-r044-20220313
|   |-- nd_perf.c:(.text):undefined-reference-to-perf_pmu_migrate_context
|   |-- nd_perf.c:(.text):undefined-reference-to-perf_pmu_register
|   `-- nd_perf.c:(.text):undefined-reference-to-perf_pmu_unregister

Similar build failure in nds32 architecture:
nd_perf.c:(.text+0x21e): undefined reference to `perf_pmu_migrate_context'
nd_perf.c:(.text+0x434): undefined reference to `perf_pmu_register'
nd_perf.c:(.text+0x57c): undefined reference to `perf_pmu_unregister'

Fix this issue by adding check for CONFIG_PERF_EVENTS config option
and disabling the nvdimm perf interface incase this config is not set.

Also removed function declaration of perf_pmu_migrate_context,
perf_pmu_register, perf_pmu_unregister functions from nd.h as these are
common pmu functions which are part of perf_event.h and since we
are disabling nvdimm perf interface incase CONFIG_PERF_EVENTS option
is not set, we not need to declare them in nd.h

Fixes: 0fab1ba6ad6b ("drivers/nvdimm: Add perf interface to expose
nvdimm performance stats") (Commit id based on linux-next tree)
Signed-off-by: Kajol Jain <kjain@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/62317124.YBQFU33+s%2FwdvWGj%25lkp@xxxxxxxxx/
Reported-by: kernel test robot <lkp@xxxxxxxxx>
---
 drivers/nvdimm/Makefile | 2 +-
 include/linux/nd.h      | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)

---
- This fix patch changes are added and tested on top of linux-next tree
  on the 'next-20220315' branch.
---
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
index 3fb806748716..ba0296dca9db 100644
--- a/drivers/nvdimm/Makefile
+++ b/drivers/nvdimm/Makefile
@@ -15,7 +15,7 @@ nd_e820-y := e820.o
 libnvdimm-y := core.o
 libnvdimm-y += bus.o
 libnvdimm-y += dimm_devs.o
-libnvdimm-y += nd_perf.o
+libnvdimm-$(CONFIG_PERF_EVENTS) += nd_perf.o
 libnvdimm-y += dimm.o
 libnvdimm-y += region_devs.o
 libnvdimm-y += region.o
diff --git a/include/linux/nd.h b/include/linux/nd.h
index 7b2ccbdc1cbc..a4265eaf5ae8 100644
--- a/include/linux/nd.h
+++ b/include/linux/nd.h
@@ -8,8 +8,10 @@
 #include <linux/ndctl.h>
 #include <linux/device.h>
 #include <linux/badblocks.h>
+#ifdef CONFIG_PERF_EVENTS
 #include <linux/perf_event.h>
 #include <linux/platform_device.h>
+#endif
 
 enum nvdimm_event {
 	NVDIMM_REVALIDATE_POISON,
@@ -25,6 +27,7 @@ enum nvdimm_claim_class {
 	NVDIMM_CCLASS_UNKNOWN,
 };
 
+#ifdef CONFIG_PERF_EVENTS
 #define NVDIMM_EVENT_VAR(_id)  event_attr_##_id
 #define NVDIMM_EVENT_PTR(_id)  (&event_attr_##_id.attr.attr)
 
@@ -63,9 +66,7 @@ extern ssize_t nvdimm_events_sysfs_show(struct device *dev,
 
 int register_nvdimm_pmu(struct nvdimm_pmu *nvdimm, struct platform_device *pdev);
 void unregister_nvdimm_pmu(struct nvdimm_pmu *nd_pmu);
-void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu);
-int perf_pmu_register(struct pmu *pmu, const char *name, int type);
-void perf_pmu_unregister(struct pmu *pmu);
+#endif
 
 struct nd_device_driver {
 	struct device_driver drv;
-- 
2.31.1