ARM: perf: handle armpmu_register failing

Currently perf_pmu_register may fail for several reasons (e.g. being
unable to allocate memory for the struct device it associates with each
PMU), and while any error is propagated by armpmu_register, it is
ignored by cpu_pmu_device_probe and not propagated to the caller.  This
also results in a leak of a struct arm_pmu.

This patch adds cleanup if armpmu_register fails, and updates the info
messages to better differentiate this type of failure from a failure to
probe the PMU type from the hardware or dt.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm/kernel/perf_event_cpu.c

@@ -277,17 +277,22 @@ static int cpu_pmu_device_probe(struct platform_device *pdev)
 	}
 
 	if (ret) {
-		pr_info("failed to register PMU devices!");
-		kfree(pmu);
-		return ret;
+		pr_info("failed to probe PMU!");
+		goto out_free;
 	}
 
 	cpu_pmu = pmu;
 	cpu_pmu->plat_device = pdev;
 	cpu_pmu_init(cpu_pmu);
-	armpmu_register(cpu_pmu, PERF_TYPE_RAW);
+	ret = armpmu_register(cpu_pmu, PERF_TYPE_RAW);
 
+	if (!ret)
 		return 0;
+
+out_free:
+	pr_info("failed to register PMU devices!");
+	kfree(pmu);
+	return ret;
 }
 
 static struct platform_driver cpu_pmu_driver = {