[PATCH 5.4 342/434] s390/cpumf: Adjust registration of s390 PMU device drivers

Greg Kroah-Hartman
2019-12-29T17:55:03Z

From: Thomas Richter <tmricht@linux.ibm.com>

[ Upstream commit 6a82e23f45fe0aa821e7a935e39d0acb20c275c0 ]

Linux-next commit titled "perf/core: Optimize perf_init_event()"
changed the semantics of PMU device driver registration.
It was done to speed up the lookup/handling of PMU device driver
specific events. It also enforces that only one PMU device
driver will be registered of type PERF_EVENT_RAW.

This change added these line in function perf_pmu_register():

...
+ ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL);
+ if (ret < 0)
goto free_pdc;
+
+ WARN_ON(type >= 0 && ret != type);

The warn_on generates a message. We have 3 PMU device drivers,
each registered as type PERF_TYPE_RAW.
The cf_diag device driver (arch/s390/kernel/perf_cpumf_cf_diag.c)
always hits the WARN_ON because it is the second PMU device driver
(after sampling device driver arch/s390/kernel/perf_cpumf_sf.c)
which is registered as type 4 (PERF_TYPE_RAW).
So when the sampling device driver is registered, ret has value 4.
When cf_diag device driver is registered with type 4,
ret has value of 5 and WARN_ON fires.

Adjust the PMU device drivers for s390 to support the new
semantics required by perf_pmu_register().

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/kernel/perf_cpum_cf.c | 21 ++++++++++-----------
arch/s390/kernel/perf_cpum_cf_diag.c | 10 +++++-----
2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c
index 48d48b6187c0..0eb1d1cc53a8 100644
--- a/arch/s390/kernel/perf_cpum_cf.c
+++ b/arch/s390/kernel/perf_cpum_cf.c
@@ -199,7 +199,7 @@ static const int cpumf_generic_events_user[] = {
[PERF_COUNT_HW_BUS_CYCLES] = -1,
};

-static int __hw_perf_event_init(struct perf_event *event)
+static int __hw_perf_event_init(struct perf_event *event, unsigned int type)
{
struct perf_event_attr *attr = &event->attr;
struct hw_perf_event *hwc = &event->hw;
@@ -207,7 +207,7 @@ static int __hw_perf_event_init(struct perf_event *event)
int err = 0;
u64 ev;

- switch (attr->type) {
+ switch (type) {
case PERF_TYPE_RAW:
/* Raw events are used to access counters directly,
* hence do not permit excludes */
@@ -294,17 +294,16 @@ static int __hw_perf_event_init(struct perf_event *event)

static int cpumf_pmu_event_init(struct perf_event *event)
{
+ unsigned int type = event->attr.type;
int err;

- switch (event->attr.type) {
- case PERF_TYPE_HARDWARE:
- case PERF_TYPE_HW_CACHE:
- case PERF_TYPE_RAW:
- err = __hw_perf_event_init(event);
- break;
- default:
+ if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_RAW)
+ err = __hw_perf_event_init(event, type);
+ else if (event->pmu->type == type)
+ /* Registered as unknown PMU */
+ err = __hw_perf_event_init(event, PERF_TYPE_RAW);
+ else
return -ENOENT;
- }

if (unlikely(err) && event->destroy)
event->destroy(event);
@@ -553,7 +552,7 @@ static int __init cpumf_pmu_init(void)
return -ENODEV;

cpumf_pmu.attr_groups = cpumf_cf_event_group();
- rc = perf_pmu_register(&cpumf_pmu, "cpum_cf", PERF_TYPE_RAW);
+ rc = perf_pmu_register(&cpumf_pmu, "cpum_cf", -1);
if (rc)
pr_err("Registering the cpum_cf PMU failed with rc=%i\n", rc);
return rc;
diff --git a/arch/s390/kernel/perf_cpum_cf_diag.c b/arch/s390/kernel/perf_cpum_cf_diag.c
index 2654e348801a..e949ab832ed7 100644
--- a/arch/s390/kernel/perf_cpum_cf_diag.c
+++ b/arch/s390/kernel/perf_cpum_cf_diag.c
@@ -243,13 +243,13 @@ static int cf_diag_event_init(struct perf_event *event)
int err = -ENOENT;

debug_sprintf_event(cf_diag_dbg, 5,
- "%s event %p cpu %d config %#llx "
+ "%s event %p cpu %d config %#llx type:%u "
"sample_type %#llx cf_diag_events %d\n", __func__,
- event, event->cpu, attr->config, attr->sample_type,
- atomic_read(&cf_diag_events));
+ event, event->cpu, attr->config, event->pmu->type,
+ attr->sample_type, atomic_read(&cf_diag_events));

if (event->attr.config != PERF_EVENT_CPUM_CF_DIAG ||
- event->attr.type != PERF_TYPE_RAW)
+ event->attr.type != event->pmu->type)
goto out;

/* Raw events are used to access counters directly,
@@ -693,7 +693,7 @@ static int __init cf_diag_init(void)
}
debug_register_view(cf_diag_dbg, &debug_sprintf_view);

- rc = perf_pmu_register(&cf_diag, "cpum_cf_diag", PERF_TYPE_RAW);
+ rc = perf_pmu_register(&cf_diag, "cpum_cf_diag", -1);
if (rc) {
debug_unregister_view(cf_diag_dbg, &debug_sprintf_view);
debug_unregister(cf_diag_dbg);
--
2.20.1