RDMA/netlink: Remove netlink clients infrastructure

RDMA netlink has a complicated infrastructure for dynamically
registering and de-registering netlink clients to the NETLINK_RDMA
group. The complicated portion of this code is not widely used because
2 of the 3 current clients are statically compiled together with
netlink.c. The infrastructure, therefore, is deemed overkill.

Refactor the code to eliminate the dynamically added clients. Now all
clients are pre-registered in a client array at compile time, and at run
time they merely check-in with the infrastructure to pass their callback
table for inclusion in the pre-sized client array.

This also allows for future cleanups and removal of unneeded code in the
iwcm* netlink handler.

Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Chien Tin Tung <chien.tin.tung@intel.com>

6 files changed, 112 insertions, 151 deletions

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index ca4135c596ba..2a16a559bdda 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -4512,9 +4512,7 @@ static int __init cma_init(void)
 	if (ret)
 		goto err;
 
-	if (ibnl_add_client(RDMA_NL_RDMA_CM, ARRAY_SIZE(cma_cb_table),
-			    cma_cb_table))
-		pr_warn("RDMA CMA: failed to add netlink callback\n");
+	rdma_nl_register(RDMA_NL_RDMA_CM, cma_cb_table);
 	cma_configfs_init();
 
 	return 0;
@@ -4531,7 +4529,7 @@ err_wq:
 static void __exit cma_cleanup(void)
 {
 	cma_configfs_exit();
-	ibnl_remove_client(RDMA_NL_RDMA_CM);
+	rdma_nl_unregister(RDMA_NL_RDMA_CM);
 	ib_unregister_client(&cma_client);
 	unregister_netdevice_notifier(&cma_nb);
 	rdma_addr_unregister_client(&addr_client);
diff --git a/drivers/infiniband/core/core_priv.h b/drivers/infiniband/core/core_priv.h
index 11ae67514e13..e759c27113cd 100644
--- a/drivers/infiniband/core/core_priv.h
+++ b/drivers/infiniband/core/core_priv.h
@@ -179,8 +179,8 @@ void ib_mad_cleanup(void);
 int ib_sa_init(void);
 void ib_sa_cleanup(void);
 
-int ibnl_init(void);
-void ibnl_cleanup(void);
+int rdma_nl_init(void);
+void rdma_nl_exit(void);
 
 /**
  * Check if there are any listeners to the netlink group
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index a5dfab6adf49..d0994cd30eae 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -1086,29 +1086,15 @@ struct net_device *ib_get_net_dev_by_params(struct ib_device *dev,
 }
 EXPORT_SYMBOL(ib_get_net_dev_by_params);
 
-static struct ibnl_client_cbs ibnl_ls_cb_table[] = {
+static const struct ibnl_client_cbs ibnl_ls_cb_table[] = {
 	[RDMA_NL_LS_OP_RESOLVE] = {
-		.dump = ib_nl_handle_resolve_resp,
-		.module = THIS_MODULE },
+		.dump = ib_nl_handle_resolve_resp},
 	[RDMA_NL_LS_OP_SET_TIMEOUT] = {
-		.dump = ib_nl_handle_set_timeout,
-		.module = THIS_MODULE },
+		.dump = ib_nl_handle_set_timeout},
 	[RDMA_NL_LS_OP_IP_RESOLVE] = {
-		.dump = ib_nl_handle_ip_res_resp,
-		.module = THIS_MODULE },
+		.dump = ib_nl_handle_ip_res_resp},
 };
 
-static int ib_add_ibnl_clients(void)
-{
-	return ibnl_add_client(RDMA_NL_LS, ARRAY_SIZE(ibnl_ls_cb_table),
-			       ibnl_ls_cb_table);
-}
-
-static void ib_remove_ibnl_clients(void)
-{
-	ibnl_remove_client(RDMA_NL_LS);
-}
-
 static int __init ib_core_init(void)
 {
 	int ret;
@@ -1130,9 +1116,9 @@ static int __init ib_core_init(void)
 		goto err_comp;
 	}
 
-	ret = ibnl_init();
+	ret = rdma_nl_init();
 	if (ret) {
-		pr_warn("Couldn't init IB netlink interface\n");
+		pr_warn("Couldn't init IB netlink interface: err %d\n", ret);
 		goto err_sysfs;
 	}
 
@@ -1154,24 +1140,17 @@ static int __init ib_core_init(void)
 		goto err_mad;
 	}
 
-	ret = ib_add_ibnl_clients();
-	if (ret) {
-		pr_warn("Couldn't register ibnl clients\n");
-		goto err_sa;
-	}
-
 	ret = register_lsm_notifier(&ibdev_lsm_nb);
 	if (ret) {
 		pr_warn("Couldn't register LSM notifier. ret %d\n", ret);
-		goto err_ibnl_clients;
+		goto err_sa;
 	}
 
+	rdma_nl_register(RDMA_NL_LS, ibnl_ls_cb_table);
 	ib_cache_setup();
 
 	return 0;
 
-err_ibnl_clients:
-	ib_remove_ibnl_clients();
 err_sa:
 	ib_sa_cleanup();
 err_mad:
@@ -1179,7 +1158,7 @@ err_mad:
 err_addr:
 	addr_cleanup();
 err_ibnl:
-	ibnl_cleanup();
+	rdma_nl_exit();
 err_sysfs:
 	class_unregister(&ib_class);
 err_comp:
@@ -1191,13 +1170,13 @@ err:
 
 static void __exit ib_core_cleanup(void)
 {
-	unregister_lsm_notifier(&ibdev_lsm_nb);
 	ib_cache_cleanup();
-	ib_remove_ibnl_clients();
+	rdma_nl_unregister(RDMA_NL_LS);
+	unregister_lsm_notifier(&ibdev_lsm_nb);
 	ib_sa_cleanup();
 	ib_mad_cleanup();
 	addr_cleanup();
-	ibnl_cleanup();
+	rdma_nl_exit();
 	class_unregister(&ib_class);
 	destroy_workqueue(ib_comp_wq);
 	/* Make sure that any pending umem accounting work is done. */
diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c
index 31661b5c1743..8599271d8be6 100644
--- a/drivers/infiniband/core/iwcm.c
+++ b/drivers/infiniband/core/iwcm.c
@@ -1175,12 +1175,8 @@ static int __init iw_cm_init(void)
 	ret = iwpm_init(RDMA_NL_IWCM);
 	if (ret)
 		pr_err("iw_cm: couldn't init iwpm\n");
-
-	ret = ibnl_add_client(RDMA_NL_IWCM, ARRAY_SIZE(iwcm_nl_cb_table),
-			      iwcm_nl_cb_table);
-	if (ret)
-		pr_err("iw_cm: couldn't register netlink callbacks\n");
-
+	else
+		rdma_nl_register(RDMA_NL_IWCM, iwcm_nl_cb_table);
 	iwcm_wq = alloc_ordered_workqueue("iw_cm_wq", WQ_MEM_RECLAIM);
 	if (!iwcm_wq)
 		return -ENOMEM;
@@ -1200,7 +1196,7 @@ static void __exit iw_cm_cleanup(void)
 {
 	unregister_net_sysctl_table(iwcm_ctl_table_hdr);
 	destroy_workqueue(iwcm_wq);
-	ibnl_remove_client(RDMA_NL_IWCM);
+	rdma_nl_unregister(RDMA_NL_IWCM);
 	iwpm_exit(RDMA_NL_IWCM);
 }
 
diff --git a/drivers/infiniband/core/netlink.c b/drivers/infiniband/core/netlink.c
index 0fc50e15ae22..06f7ba31fbdd 100644
--- a/drivers/infiniband/core/netlink.c
+++ b/drivers/infiniband/core/netlink.c
@@ -39,16 +39,13 @@
 #include <rdma/rdma_netlink.h>
 #include "core_priv.h"
 
-struct ibnl_client {
-	struct list_head		list;
-	int				index;
-	int				nops;
-	const struct ibnl_client_cbs   *cb_table;
-};
+#include "core_priv.h"
 
-static DEFINE_MUTEX(ibnl_mutex);
+static DEFINE_MUTEX(rdma_nl_mutex);
 static struct sock *nls;
-static LIST_HEAD(client_list);
+static struct {
+	const struct ibnl_client_cbs   *cb_table;
+} rdma_nl_types[RDMA_NL_NUM_CLIENTS];
 
 int ibnl_chk_listeners(unsigned int group)
 {
@@ -57,58 +54,74 @@ int ibnl_chk_listeners(unsigned int group)
 	return 0;
 }
 
-int ibnl_add_client(int index, int nops,
-		    const struct ibnl_client_cbs cb_table[])
+static bool is_nl_msg_valid(unsigned int type, unsigned int op)
 {
-	struct ibnl_client *cur;
-	struct ibnl_client *nl_client;
+	static const unsigned int max_num_ops[RDMA_NL_NUM_CLIENTS - 1] = {
+				  RDMA_NL_RDMA_CM_NUM_OPS,
+				  RDMA_NL_IWPM_NUM_OPS,
+				  0,
+				  RDMA_NL_LS_NUM_OPS,
+				  0 };
 
-	nl_client = kmalloc(sizeof *nl_client, GFP_KERNEL);
-	if (!nl_client)
-		return -ENOMEM;
+	/*
+	 * This BUILD_BUG_ON is intended to catch addition of new
+	 * RDMA netlink protocol without updating the array above.
+	 */
+	BUILD_BUG_ON(RDMA_NL_NUM_CLIENTS != 6);
 
-	nl_client->index	= index;
-	nl_client->nops		= nops;
-	nl_client->cb_table	= cb_table;
+	if (type > RDMA_NL_NUM_CLIENTS - 1)
+		return false;
 
-	mutex_lock(&ibnl_mutex);
+	return (op < max_num_ops[type - 1]) ? true : false;
+}
 
-	list_for_each_entry(cur, &client_list, list) {
-		if (cur->index == index) {
-			pr_warn("Client for %d already exists\n", index);
-			mutex_unlock(&ibnl_mutex);
-			kfree(nl_client);
-			return -EINVAL;
-		}
-	}
+static bool is_nl_valid(unsigned int type, unsigned int op)
+{
+	if (!is_nl_msg_valid(type, op) ||
+	    !rdma_nl_types[type].cb_table ||
+	    !rdma_nl_types[type].cb_table[op].dump)
+		return false;
+	return true;
+}
 
-	list_add_tail(&nl_client->list, &client_list);
+void rdma_nl_register(unsigned int index,
+		      const struct ibnl_client_cbs cb_table[])
+{
+	mutex_lock(&rdma_nl_mutex);
+	if (!is_nl_msg_valid(index, 0)) {
+		/*
+		 * All clients are not interesting in success/failure of
+		 * this call. They want to see the print to error log and
+		 * continue their initialization. Print warning for them,
+		 * because it is programmer's error to be here.
+		 */
+		mutex_unlock(&rdma_nl_mutex);
+		WARN(true,
+		     "The not-valid %u index was supplied to RDMA netlink\n",
+		     index);
+		return;
+	}
 
-	mutex_unlock(&ibnl_mutex);
+	if (rdma_nl_types[index].cb_table) {
+		mutex_unlock(&rdma_nl_mutex);
+		WARN(true,
+		     "The %u index is already registered in RDMA netlink\n",
+		     index);
+		return;
+	}
 
-	return 0;
+	rdma_nl_types[index].cb_table = cb_table;
+	mutex_unlock(&rdma_nl_mutex);
 }
-EXPORT_SYMBOL(ibnl_add_client);
+EXPORT_SYMBOL(rdma_nl_register);
 
-int ibnl_remove_client(int index)
+void rdma_nl_unregister(unsigned int index)
 {
-	struct ibnl_client *cur, *next;
-
-	mutex_lock(&ibnl_mutex);
-	list_for_each_entry_safe(cur, next, &client_list, list) {
-		if (cur->index == index) {
-			list_del(&(cur->list));
-			mutex_unlock(&ibnl_mutex);
-			kfree(cur);
-			return 0;
-		}
-	}
-	pr_warn("Can't remove callback for client idx %d. Not found\n", index);
-	mutex_unlock(&ibnl_mutex);
-
-	return -EINVAL;
+	mutex_lock(&rdma_nl_mutex);
+	rdma_nl_types[index].cb_table = NULL;
+	mutex_unlock(&rdma_nl_mutex);
 }
-EXPORT_SYMBOL(ibnl_remove_client);
+EXPORT_SYMBOL(rdma_nl_unregister);
 
 void *ibnl_put_msg(struct sk_buff *skb, struct nlmsghdr **nlh, int seq,
 		   int len, int client, int op, int flags)
@@ -149,45 +162,31 @@ EXPORT_SYMBOL(ibnl_put_attr);
 static int ibnl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 			struct netlink_ext_ack *extack)
 {
-	struct ibnl_client *client;
 	int type = nlh->nlmsg_type;
-	int index = RDMA_NL_GET_CLIENT(type);
+	unsigned int index = RDMA_NL_GET_CLIENT(type);
 	unsigned int op = RDMA_NL_GET_OP(type);
+	struct netlink_callback cb = {};
+	struct netlink_dump_control c = {};
 
-	list_for_each_entry(client, &client_list, list) {
-		if (client->index == index) {
-			if (op >= client->nops || !client->cb_table[op].dump)
-				return -EINVAL;
-
-			/*
-			 * For response or local service set_timeout request,
-			 * there is no need to use netlink_dump_start.
-			 */
-			if (!(nlh->nlmsg_flags & NLM_F_REQUEST) ||
-			    (index == RDMA_NL_LS &&
-			     op == RDMA_NL_LS_OP_SET_TIMEOUT)) {
-				struct netlink_callback cb = {
-					.skb = skb,
-					.nlh = nlh,
-					.dump = client->cb_table[op].dump,
-					.module = client->cb_table[op].module,
-				};
-
-				return cb.dump(skb, &cb);
-			}
-
-			{
-				struct netlink_dump_control c = {
-					.dump = client->cb_table[op].dump,
-					.module = client->cb_table[op].module,
-				};
-				return netlink_dump_start(nls, skb, nlh, &c);
-			}
-		}
+	if (!is_nl_valid(index, op))
+		return -EINVAL;
+
+	/*
+	 * For response or local service set_timeout request,
+	 * there is no need to use netlink_dump_start.
+	 */
+	if (!(nlh->nlmsg_flags & NLM_F_REQUEST) ||
+	    (index == RDMA_NL_LS && op == RDMA_NL_LS_OP_SET_TIMEOUT)) {
+		cb.skb = skb;
+		cb.nlh = nlh;
+		cb.dump = rdma_nl_types[index].cb_table[op].dump;
+		cb.module = rdma_nl_types[index].cb_table[op].module;
+		return cb.dump(skb, &cb);
 	}
 
-	pr_info("Index %d wasn't found in client list\n", index);
-	return -EINVAL;
+	c.dump = rdma_nl_types[index].cb_table[op].dump;
+	c.module = rdma_nl_types[index].cb_table[op].module;
+	return netlink_dump_start(nls, skb, nlh, &c);
 }
 
 static void ibnl_rcv_reply_skb(struct sk_buff *skb)
@@ -221,10 +220,10 @@ static void ibnl_rcv_reply_skb(struct sk_buff *skb)
 
 static void ibnl_rcv(struct sk_buff *skb)
 {
-	mutex_lock(&ibnl_mutex);
+	mutex_lock(&rdma_nl_mutex);
 	ibnl_rcv_reply_skb(skb);
 	netlink_rcv_skb(skb, &ibnl_rcv_msg);
-	mutex_unlock(&ibnl_mutex);
+	mutex_unlock(&rdma_nl_mutex);
 }
 
 int ibnl_unicast(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -254,32 +253,26 @@ int ibnl_multicast(struct sk_buff *skb, struct nlmsghdr *nlh,
 }
 EXPORT_SYMBOL(ibnl_multicast);
 
-int __init ibnl_init(void)
+int __init rdma_nl_init(void)
 {
 	struct netlink_kernel_cfg cfg = {
 		.input	= ibnl_rcv,
 	};
 
 	nls = netlink_kernel_create(&init_net, NETLINK_RDMA, &cfg);
-	if (!nls) {
-		pr_warn("Failed to create netlink socket\n");
+	if (!nls)
 		return -ENOMEM;
-	}
 
 	nls->sk_sndtimeo = 10 * HZ;
 	return 0;
 }
 
-void ibnl_cleanup(void)
+void rdma_nl_exit(void)
 {
-	struct ibnl_client *cur, *next;
+	int idx;
 
-	mutex_lock(&ibnl_mutex);
-	list_for_each_entry_safe(cur, next, &client_list, list) {
-		list_del(&(cur->list));
-		kfree(cur);
-	}
-	mutex_unlock(&ibnl_mutex);
+	for (idx = 0; idx < RDMA_NL_NUM_CLIENTS; idx++)
+		rdma_nl_unregister(idx);
 
 	netlink_kernel_release(nls);
 }
diff --git a/include/rdma/rdma_netlink.h b/include/rdma/rdma_netlink.h
index 5b1466770917..aadf0ab963b2 100644
--- a/include/rdma/rdma_netlink.h
+++ b/include/rdma/rdma_netlink.h
@@ -11,23 +11,18 @@ struct ibnl_client_cbs {
 };
 
 /**
- * Add a a client to the list of IB netlink exporters.
+ * Register client in RDMA netlink.
  * @index: Index of the added client
- * @nops: Number of supported ops by the added client.
  * @cb_table: A table for op->callback
- *
- * Returns 0 on success or a negative error code.
  */
-int ibnl_add_client(int index, int nops,
-		    const struct ibnl_client_cbs cb_table[]);
+void rdma_nl_register(unsigned int index,
+		      const struct ibnl_client_cbs cb_table[]);
 
 /**
  * Remove a client from IB netlink.
  * @index: Index of the removed IB client.
- *
- * Returns 0 on success or a negative error code.
  */
-int ibnl_remove_client(int index);
+void rdma_nl_unregister(unsigned int index);
 
 /**
  * Put a new message in a supplied skb.