perf/arm-cmn: Fail DTC counter allocation correctly

Calling arm_cmn_event_clear() before all DTC indices are allocated is
wrong, and can lead to arm_cmn_event_add() erroneously clearing live
counters from full DTCs where allocation fails. Since the DTC counters
are only updated by arm_cmn_init_counter() after all DTC and DTM
allocations succeed, nothing actually needs cleaning up in this case
anyway, and it should just return directly as it did before.

Fixes: 7633ec2 ("perf/arm-cmn: Rework DTC counters (again)")
Signed-off-by: Robin Murphy <[email protected]>
Reviewed-by: Ilkka Koskinen <[email protected]>
Acked-by: Will Deacon <[email protected]>
Link: https://lore.kernel.org/r/ed589c0d8e4130dc68b8ad1625226d28bdc185d4.1702322847.git.robin.murphy@arm.com
Signed-off-by: Catalin Marinas <[email protected]>

Author: rmurphy-arm

drivers/perf/arm-cmn.c

@@ -1816,7 +1816,7 @@ static int arm_cmn_event_add(struct perf_event *event, int flags)
 			idx = 0;
 			while (cmn->dtc[j].counters[idx])
 				if (++idx == CMN_DT_NUM_COUNTERS)
-					goto free_dtms;
+					return -ENOSPC;
 		}
 		hw->dtc_idx[j] = idx;
 	}