drivers/perf: hisi: add NULL check for name

When allocations fails that can be NULL now.

If the name provided is NULL, then the initialization process of the PMU
type and dev will be skipped in function perf_pmu_register().
Consequently, the PMU will not be able to register into the kernel.
Moreover, in the case of unregister the PMU, the function device_del()
will need to handle NULL pointers, which potentially can cause issues.

So move this allocation above the cpuhp_state_add_instance() and directly
return if it does fail.

Signed-off-by: Junhao He <hejunhao3@huawei.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230403081423.62460-3-hejunhao3@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

Author: Junhao He

drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c

@@ -499,13 +499,6 @@ static int hisi_ddrc_pmu_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ret = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_HISI_DDRC_ONLINE,
-				       &ddrc_pmu->node);
-	if (ret) {
-		dev_err(&pdev->dev, "Error %d registering hotplug;\n", ret);
-		return ret;
-	}
-
 	if (ddrc_pmu->identifier >= HISI_PMU_V2)
 		name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
 				      "hisi_sccl%u_ddrc%u_%u",
@@ -516,6 +509,16 @@ static int hisi_ddrc_pmu_probe(struct platform_device *pdev)
 				      "hisi_sccl%u_ddrc%u", ddrc_pmu->sccl_id,
 				      ddrc_pmu->index_id);
 
+	if (!name)
+		return -ENOMEM;
+
+	ret = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_HISI_DDRC_ONLINE,
+				       &ddrc_pmu->node);
+	if (ret) {
+		dev_err(&pdev->dev, "Error %d registering hotplug;\n", ret);
+		return ret;
+	}
+
 	hisi_pmu_init(ddrc_pmu, THIS_MODULE);
 
 	ret = perf_pmu_register(&ddrc_pmu->pmu, name, -1);

drivers/perf/hisilicon/hisi_uncore_hha_pmu.c

@@ -510,15 +510,18 @@ static int hisi_hha_pmu_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "hisi_sccl%u_hha%u",
+			      hha_pmu->sccl_id, hha_pmu->index_id);
+	if (!name)
+		return -ENOMEM;
+
 	ret = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_HISI_HHA_ONLINE,
 				       &hha_pmu->node);
 	if (ret) {
 		dev_err(&pdev->dev, "Error %d registering hotplug\n", ret);
 		return ret;
 	}
 
-	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "hisi_sccl%u_hha%u",
-			      hha_pmu->sccl_id, hha_pmu->index_id);
 	hisi_pmu_init(hha_pmu, THIS_MODULE);
 
 	ret = perf_pmu_register(&hha_pmu->pmu, name, -1);

drivers/perf/hisilicon/hisi_uncore_l3c_pmu.c

@@ -544,19 +544,18 @@ static int hisi_l3c_pmu_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "hisi_sccl%u_l3c%u",
+			      l3c_pmu->sccl_id, l3c_pmu->ccl_id);
+	if (!name)
+		return -ENOMEM;
+
 	ret = cpuhp_state_add_instance(CPUHP_AP_PERF_ARM_HISI_L3_ONLINE,
 				       &l3c_pmu->node);
 	if (ret) {
 		dev_err(&pdev->dev, "Error %d registering hotplug\n", ret);
 		return ret;
 	}
 
-	/*
-	 * CCL_ID is used to identify the L3C in the same SCCL which was
-	 * used _UID by mistake.
-	 */
-	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "hisi_sccl%u_l3c%u",
-			      l3c_pmu->sccl_id, l3c_pmu->ccl_id);
 	hisi_pmu_init(l3c_pmu, THIS_MODULE);
 
 	ret = perf_pmu_register(&l3c_pmu->pmu, name, -1);