s390/cpumf: remove WARN_ON_ONCE in counter start handler

Remove some WARN_ON_ONCE() warnings when a counter is started. Each
counter is installed function calls
event_sched_in() --> cpumf_pmu_add(..., PERF_EF_START).

This is done after the event has been created using
perf_pmu_event_init() which verifies the counter is valid.
Member hwc->config must be valid at this point.

Function cpumf_pmu_start(..., PERF_EF_RELOAD) is called from
function cpumf_pmu_add() for counter events. All other invocations of
cpumf_pmu_start(..., PERF_EF_RELOAD) are from the performance subsystem
for sampling events.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/perf_cpum_cf.c

@@ -362,15 +362,9 @@ static void cpumf_pmu_start(struct perf_event *event, int flags)
 	struct cpu_cf_events *cpuhw = this_cpu_ptr(&cpu_cf_events);
 	struct hw_perf_event *hwc = &event->hw;
 
-	if (WARN_ON_ONCE(!(hwc->state & PERF_HES_STOPPED)))
+	if (!(hwc->state & PERF_HES_STOPPED))
 		return;
 
-	if (WARN_ON_ONCE(hwc->config == -1))
-		return;
-
-	if (flags & PERF_EF_RELOAD)
-		WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));
-
 	hwc->state = 0;
 
 	/* (Re-)enable and activate the counter set */