[RFC PATCH 05/16] devlink: Be explicit with devlink port protection

From: Leon Romanovsky <leon@kernel.org>
Date: 2021-11-08 17:06:14
Subsystem: networking [general], the rest · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds

From: Leon Romanovsky <leonro@nvidia.com>

Devlink port flows use devlink instance lock to protect from parallel
addition and deletion from port_list. So instead of using global lock,
let's introduce specific protection lock with much more clear scope
that will protect port_list.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 net/core/devlink.c | 61 ++++++++++++++++++++++++++++++----------------
 1 file changed, 40 insertions(+), 21 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index b41ab8751635..d88e882616bc 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -41,6 +41,7 @@ struct devlink_dev_stats {
 struct devlink {
 	u32 index;
 	struct list_head port_list;
+	struct mutex port_list_lock; /* protects port_list */
 	struct list_head rate_list;
 	struct list_head sb_list;
 	struct list_head dpipe_table_list;

@@ -228,13 +229,17 @@ static struct devlink *devlink_get_from_attrs(struct net *net,
 static struct devlink_port *devlink_port_get_by_index(struct devlink *devlink,
 						      unsigned int port_index)
 {
-	struct devlink_port *devlink_port;
+	struct devlink_port *devlink_port, *res = NULL;
 
+	mutex_lock(&devlink->port_list_lock);
 	list_for_each_entry(devlink_port, &devlink->port_list, list) {
-		if (devlink_port->index == port_index)
-			return devlink_port;
+		if (devlink_port->index == port_index) {
+			res = devlink_port;
+			break;
+		}
 	}
-	return NULL;
+	mutex_unlock(&devlink->port_list_lock);
+	return res;
 }
 
 static struct devlink_port *devlink_port_get_from_attrs(struct devlink *devlink,

@@ -1341,7 +1346,7 @@ static int devlink_nl_cmd_port_get_dumpit(struct sk_buff *msg,
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
 			goto retry;
 
-		mutex_lock(&devlink->lock);
+		mutex_lock(&devlink->port_list_lock);
 		list_for_each_entry(devlink_port, &devlink->port_list, list) {
 			if (idx < start) {
 				idx++;

@@ -1353,13 +1358,13 @@ static int devlink_nl_cmd_port_get_dumpit(struct sk_buff *msg,
 						   cb->nlh->nlmsg_seq,
 						   NLM_F_MULTI, cb->extack);
 			if (err) {
-				mutex_unlock(&devlink->lock);
+				mutex_unlock(&devlink->port_list_lock);
 				devlink_put(devlink);
 				goto out;
 			}
 			idx++;
 		}
-		mutex_unlock(&devlink->lock);
+		mutex_unlock(&devlink->port_list_lock);
 retry:
 		devlink_put(devlink);
 	}

@@ -2567,8 +2572,9 @@ static int __sb_tc_pool_bind_get_dumpit(struct sk_buff *msg,
 {
 	struct devlink_port *devlink_port;
 	u16 tc_index;
-	int err;
+	int err = 0;
 
+	mutex_lock(&devlink->port_list_lock);
 	list_for_each_entry(devlink_port, &devlink->port_list, list) {
 		for (tc_index = 0;
 		     tc_index < devlink_sb->ingress_tc_count; tc_index++) {

@@ -2585,7 +2591,7 @@ static int __sb_tc_pool_bind_get_dumpit(struct sk_buff *msg,
 							      portid, seq,
 							      NLM_F_MULTI);
 			if (err)
-				return err;
+				goto out;
 			(*p_idx)++;
 		}
 		for (tc_index = 0;

@@ -2603,11 +2609,13 @@ static int __sb_tc_pool_bind_get_dumpit(struct sk_buff *msg,
 							      portid, seq,
 							      NLM_F_MULTI);
 			if (err)
-				return err;
+				goto out;
 			(*p_idx)++;
 		}
 	}
-	return 0;
+out:
+	mutex_unlock(&devlink->port_list_lock);
+	return err;
 }
 
 static int

@@ -4938,7 +4946,7 @@ static int devlink_nl_cmd_port_param_get_dumpit(struct sk_buff *msg,
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
 			goto retry;
 
-		mutex_lock(&devlink->lock);
+		mutex_lock(&devlink->port_list_lock);
 		list_for_each_entry(devlink_port, &devlink->port_list, list) {
 			list_for_each_entry(param_item,
 					    &devlink_port->param_list, list) {

@@ -4956,14 +4964,14 @@ static int devlink_nl_cmd_port_param_get_dumpit(struct sk_buff *msg,
 				if (err == -EOPNOTSUPP) {
 					err = 0;
 				} else if (err) {
-					mutex_unlock(&devlink->lock);
+					mutex_unlock(&devlink->port_list_lock);
 					devlink_put(devlink);
 					goto out;
 				}
 				idx++;
 			}
 		}
-		mutex_unlock(&devlink->lock);
+		mutex_unlock(&devlink->port_list_lock);
 retry:
 		devlink_put(devlink);
 	}

@@ -5481,6 +5489,7 @@ static int devlink_nl_cmd_region_get_devlink_dumpit(struct sk_buff *msg,
 		(*idx)++;
 	}
 
+	mutex_lock(&devlink->port_list_lock);
 	list_for_each_entry(port, &devlink->port_list, list) {
 		err = devlink_nl_cmd_region_get_port_dumpit(msg, cb, port, idx,
 							    start);

@@ -5489,6 +5498,7 @@ static int devlink_nl_cmd_region_get_devlink_dumpit(struct sk_buff *msg,
 	}
 
 out:
+	mutex_unlock(&devlink->port_list_lock);
 	mutex_unlock(&devlink->lock);
 	return err;
 }

@@ -7254,7 +7264,7 @@ devlink_nl_cmd_health_reporter_get_dumpit(struct sk_buff *msg,
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
 			goto retry_port;
 
-		mutex_lock(&devlink->lock);
+		mutex_lock(&devlink->port_list_lock);
 		list_for_each_entry(port, &devlink->port_list, list) {
 			mutex_lock(&port->reporters_lock);
 			list_for_each_entry(reporter, &port->reporter_list, list) {

@@ -7269,7 +7279,7 @@ devlink_nl_cmd_health_reporter_get_dumpit(struct sk_buff *msg,
 					cb->nlh->nlmsg_seq, NLM_F_MULTI);
 				if (err) {
 					mutex_unlock(&port->reporters_lock);
-					mutex_unlock(&devlink->lock);
+					mutex_unlock(&devlink->port_list_lock);
 					devlink_put(devlink);
 					goto out;
 				}

@@ -7277,7 +7287,7 @@ devlink_nl_cmd_health_reporter_get_dumpit(struct sk_buff *msg,
 			}
 			mutex_unlock(&port->reporters_lock);
 		}
-		mutex_unlock(&devlink->lock);
+		mutex_unlock(&devlink->port_list_lock);
 retry_port:
 		devlink_put(devlink);
 	}

@@ -8978,7 +8988,10 @@ struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
 	devlink->ops = ops;
 	xa_init_flags(&devlink->snapshot_ids, XA_FLAGS_ALLOC);
 	write_pnet(&devlink->_net, net);
+
 	INIT_LIST_HEAD(&devlink->port_list);
+	mutex_init(&devlink->port_list_lock);
+
 	INIT_LIST_HEAD(&devlink->rate_list);
 	INIT_LIST_HEAD(&devlink->sb_list);
 	INIT_LIST_HEAD_RCU(&devlink->dpipe_table_list);

@@ -9021,8 +9034,10 @@ static void devlink_notify_register(struct devlink *devlink)
 	struct devlink_region *region;
 
 	devlink_notify(devlink, DEVLINK_CMD_NEW);
+	mutex_lock(&devlink->port_list_lock);
 	list_for_each_entry(devlink_port, &devlink->port_list, list)
 		devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_NEW);
+	mutex_unlock(&devlink->port_list_lock);
 
 	list_for_each_entry(policer_item, &devlink->trap_policer_list, list)
 		devlink_trap_policer_notify(devlink, policer_item,

@@ -9077,8 +9092,11 @@ static void devlink_notify_unregister(struct devlink *devlink)
 		devlink_trap_policer_notify(devlink, policer_item,
 					    DEVLINK_CMD_TRAP_POLICER_DEL);
 
+	mutex_lock(&devlink->port_list_lock);
 	list_for_each_entry_reverse(devlink_port, &devlink->port_list, list)
 		devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_DEL);
+	mutex_unlock(&devlink->port_list_lock);
+
 	devlink_notify(devlink, DEVLINK_CMD_DEL);
 }

@@ -9129,6 +9147,7 @@ void devlink_free(struct devlink *devlink)
 	ASSERT_DEVLINK_NOT_REGISTERED(devlink);
 
 	mutex_destroy(&devlink->reporters_lock);
+	mutex_destroy(&devlink->port_list_lock);
 	mutex_destroy(&devlink->lock);
 	WARN_ON(!list_empty(&devlink->trap_policer_list));
 	WARN_ON(!list_empty(&devlink->trap_group_list));

@@ -9211,9 +9230,9 @@ void devlink_port_register(struct devlink *devlink,
 	INIT_LIST_HEAD(&devlink_port->region_list);
 	INIT_DELAYED_WORK(&devlink_port->type_warn_dw, &devlink_port_type_warn);
 
-	mutex_lock(&devlink->lock);
+	mutex_lock(&devlink->port_list_lock);
 	list_add_tail(&devlink_port->list, &devlink->port_list);
-	mutex_unlock(&devlink->lock);
+	mutex_unlock(&devlink->port_list_lock);
 
 	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_NEW);
 	devlink_port_type_warn_schedule(devlink_port);

@@ -9232,9 +9251,9 @@ void devlink_port_unregister(struct devlink_port *devlink_port)
 	devlink_port_type_warn_cancel(devlink_port);
 	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_DEL);
 
-	mutex_lock(&devlink->lock);
+	mutex_lock(&devlink->port_list_lock);
 	list_del(&devlink_port->list);
-	mutex_unlock(&devlink->lock);
+	mutex_unlock(&devlink->port_list_lock);
 
 	WARN_ON(!list_empty(&devlink_port->reporter_list));
 	WARN_ON(!list_empty(&devlink_port->region_list));

-- 
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