ARM: perf: remove unnecessary checks for idx < 0

We currently check for hwx->idx < 0 in armpmu_read and armpmu_del
unnecessarily. The only case where hwc->idx < 0 is when armpmu_add
fails, in which case the event's state is set to
PERF_EVENT_STATE_INACTIVE.

The perf core will not attempt to read from an event in
PERF_EVENT_STATE_INACTIVE, and so the check in armpmu_read is
unnecessary. Similarly, if perf core cannot add an event it will not
attempt to delete it, so the WARN_ON in armpmu_del is unnecessary.

This patch removes these two redundant checks.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm/kernel/perf_event.c

@@ -149,12 +149,6 @@ again:
 static void
 armpmu_read(struct perf_event *event)
 {
-	struct hw_perf_event *hwc = &event->hw;
-
-	/* Don't read disabled counters! */
-	if (hwc->idx < 0)
-		return;
-
 	armpmu_event_update(event);
 }
 
@@ -207,8 +201,6 @@ armpmu_del(struct perf_event *event, int flags)
 	struct hw_perf_event *hwc = &event->hw;
 	int idx = hwc->idx;
 
-	WARN_ON(idx < 0);
-
 	armpmu_stop(event, PERF_EF_UPDATE);
 	hw_events->events[idx] = NULL;
 	clear_bit(idx, hw_events->used_mask);