RDMA/rtrs-clt: Refactor the failure cases in alloc_clt

Make all failure cases go to the common path to avoid duplicate code.
And some issued existed before.

1. clt need to be freed to avoid memory leak.

2. return ERR_PTR(-ENOMEM) if kobject_create_and_add fails, because
   rtrs_clt_open checks the return value of by call "IS_ERR(clt)".

Fixes: 6a98d71d ("RDMA/rtrs: client: main functionality")
Link: https://lore.kernel.org/r/20201217141915.56989-15-jinpu.wang@cloud.ionos.comSigned-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Reviewed-by: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/ulp/rtrs/rtrs-clt.c

@@ -2568,11 +2568,8 @@ static struct rtrs_clt *alloc_clt(const char *sessname, size_t paths_num,
 	clt->dev.class = rtrs_clt_dev_class;
 	clt->dev.release = rtrs_clt_dev_release;
 	err = dev_set_name(&clt->dev, "%s", sessname);
-	if (err) {
-		free_percpu(clt->pcpu_path);
-		kfree(clt);
-		return ERR_PTR(err);
-	}
+	if (err)
+		goto err;
 	/*
 	 * Suppress user space notification until
 	 * sysfs files are created
@@ -2580,29 +2577,31 @@ static struct rtrs_clt *alloc_clt(const char *sessname, size_t paths_num,
 	dev_set_uevent_suppress(&clt->dev, true);
 	err = device_register(&clt->dev);
 	if (err) {
-		free_percpu(clt->pcpu_path);
 		put_device(&clt->dev);
-		return ERR_PTR(err);
+		goto err;
 	}
 
 	clt->kobj_paths = kobject_create_and_add("paths", &clt->dev.kobj);
 	if (!clt->kobj_paths) {
-		free_percpu(clt->pcpu_path);
-		device_unregister(&clt->dev);
-		return NULL;
+		err = -ENOMEM;
+		goto err_dev;
 	}
 	err = rtrs_clt_create_sysfs_root_files(clt);
 	if (err) {
-		free_percpu(clt->pcpu_path);
 		kobject_del(clt->kobj_paths);
 		kobject_put(clt->kobj_paths);
-		device_unregister(&clt->dev);
-		return ERR_PTR(err);
+		goto err_dev;
 	}
 	dev_set_uevent_suppress(&clt->dev, false);
 	kobject_uevent(&clt->dev.kobj, KOBJ_ADD);
 
 	return clt;
+err_dev:
+	device_unregister(&clt->dev);
+err:
+	free_percpu(clt->pcpu_path);
+	kfree(clt);
+	return ERR_PTR(err);
 }
 
 static void free_clt(struct rtrs_clt *clt)