Subject: [patch net-next v2 01/10] devlink: Add per devlink instance lock

From: Jiri Pirko <[email-masked]>
Date: Tue, 26 Dec 2017 12:23:50 +0100

From: Arkadi Sharshevsky <[email-masked]>

This is a preparation before introducing resources and hot reload support.
Currently there are two global lock where one protects all devlink access,
and the second one protects devlink port access. This patch adds per devlink
instance lock which protects the internal members which are the sb/dpipe/
resource/ports. By introducing this lock the global devlink port lock can
be discarded.

Signed-off-by: Arkadi Sharshevsky <[email-masked]>
Signed-off-by: Jiri Pirko <[email-masked]>
---
v1->v2
- Add flag for indication about not locking the devlink per-instance
  lock. It is currently used for port split commands, and will be used
  for reload as well.
---
 include/net/devlink.h |   1 +
 net/core/devlink.c    | 136 ++++++++++++++++++++++++++++----------------------
 2 files changed, 78 insertions(+), 59 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index b9654e1..4d2c6fc 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -30,6 +30,7 @@ struct devlink {
 	const struct devlink_ops *ops;
 	struct device *dev;
 	possible_net_t _net;
+	struct mutex lock;
 	char priv[0] __aligned(NETDEV_ALIGN);
 };
 
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 7d430c1..2f71734 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -92,12 +92,6 @@ static LIST_HEAD(devlink_list);
  */
 static DEFINE_MUTEX(devlink_mutex);
 
-/* devlink_port_mutex
- *
- * Shared lock to guard lists of ports in all devlink devices.
- */
-static DEFINE_MUTEX(devlink_port_mutex);
-
 static struct net *devlink_net(const struct devlink *devlink)
 {
 	return read_pnet(&devlink->_net);
@@ -335,15 +329,18 @@ devlink_sb_tc_index_get_from_info(struct devlink_sb *devlink_sb,
 #define DEVLINK_NL_FLAG_NEED_DEVLINK	BIT(0)
 #define DEVLINK_NL_FLAG_NEED_PORT	BIT(1)
 #define DEVLINK_NL_FLAG_NEED_SB		BIT(2)
-#define DEVLINK_NL_FLAG_LOCK_PORTS	BIT(3)
-	/* port is not needed but we need to ensure they don't
-	 * change in the middle of command
-	 */
+
+/* The per devlink instance lock is taken by default in the pre-doit
+ * operation, yet several commands do not require this. The global
+ * devlink lock is taken and protects from disruption by user-calls.
+ */
+#define DEVLINK_NL_FLAG_NO_LOCK		BIT(3)
 
 static int devlink_nl_pre_doit(const struct genl_ops *ops,
 			       struct sk_buff *skb, struct genl_info *info)
 {
 	struct devlink *devlink;
+	int err;
 
 	mutex_lock(&devlink_mutex);
 	devlink = devlink_get_from_info(info);
@@ -351,44 +348,47 @@ static int devlink_nl_pre_doit(const struct genl_ops *ops,
 		mutex_unlock(&devlink_mutex);
 		return PTR_ERR(devlink);
 	}
+	if (~ops->internal_flags & DEVLINK_NL_FLAG_NO_LOCK)
+		mutex_lock(&devlink->lock);
 	if (ops->internal_flags & DEVLINK_NL_FLAG_NEED_DEVLINK) {
 		info->user_ptr[0] = devlink;
 	} else if (ops->internal_flags & DEVLINK_NL_FLAG_NEED_PORT) {
 		struct devlink_port *devlink_port;
 
-		mutex_lock(&devlink_port_mutex);
 		devlink_port = devlink_port_get_from_info(devlink, info);
 		if (IS_ERR(devlink_port)) {
-			mutex_unlock(&devlink_port_mutex);
-			mutex_unlock(&devlink_mutex);
-			return PTR_ERR(devlink_port);
+			err = PTR_ERR(devlink_port);
+			goto unlock;
 		}
 		info->user_ptr[0] = devlink_port;
 	}
-	if (ops->internal_flags & DEVLINK_NL_FLAG_LOCK_PORTS) {
-		mutex_lock(&devlink_port_mutex);
-	}
 	if (ops->internal_flags & DEVLINK_NL_FLAG_NEED_SB) {
 		struct devlink_sb *devlink_sb;
 
 		devlink_sb = devlink_sb_get_from_info(devlink, info);
 		if (IS_ERR(devlink_sb)) {
-			if (ops->internal_flags & DEVLINK_NL_FLAG_NEED_PORT)
-				mutex_unlock(&devlink_port_mutex);
-			mutex_unlock(&devlink_mutex);
-			return PTR_ERR(devlink_sb);
+			err = PTR_ERR(devlink_sb);
+			goto unlock;
 		}
 		info->user_ptr[1] = devlink_sb;
 	}
 	return 0;
+
+unlock:
+	if (~ops->internal_flags & DEVLINK_NL_FLAG_NO_LOCK)
+		mutex_unlock(&devlink->lock);
+	mutex_unlock(&devlink_mutex);
+	return err;
 }
 
 static void devlink_nl_post_doit(const struct genl_ops *ops,
 				 struct sk_buff *skb, struct genl_info *info)
 {
-	if (ops->internal_flags & DEVLINK_NL_FLAG_NEED_PORT ||
-	    ops->internal_flags & DEVLINK_NL_FLAG_LOCK_PORTS)
-		mutex_unlock(&devlink_port_mutex);
+	struct devlink *devlink;
+
+	devlink = devlink_get_from_info(info);
+	if (~ops->internal_flags & DEVLINK_NL_FLAG_NO_LOCK)
+		mutex_unlock(&devlink->lock);
 	mutex_unlock(&devlink_mutex);
 }
 
@@ -614,10 +614,10 @@ static int devlink_nl_cmd_port_get_dumpit(struct sk_buff *msg,
 	int err;
 
 	mutex_lock(&devlink_mutex);
-	mutex_lock(&devlink_port_mutex);
 	list_for_each_entry(devlink, &devlink_list, list) {
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
 			continue;
+		mutex_lock(&devlink->lock);
 		list_for_each_entry(devlink_port, &devlink->port_list, list) {
 			if (idx < start) {
 				idx++;
@@ -628,13 +628,15 @@ static int devlink_nl_cmd_port_get_dumpit(struct sk_buff *msg,
 						   NETLINK_CB(cb->skb).portid,
 						   cb->nlh->nlmsg_seq,
 						   NLM_F_MULTI);
-			if (err)
+			if (err) {
+				mutex_unlock(&devlink->lock);
 				goto out;
+			}
 			idx++;
 		}
+		mutex_unlock(&devlink->lock);
 	}
 out:
-	mutex_unlock(&devlink_port_mutex);
 	mutex_unlock(&devlink_mutex);
 
 	cb->args[0] = idx;
@@ -801,6 +803,7 @@ static int devlink_nl_cmd_sb_get_dumpit(struct sk_buff *msg,
 	list_for_each_entry(devlink, &devlink_list, list) {
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
 			continue;
+		mutex_lock(&devlink->lock);
 		list_for_each_entry(devlink_sb, &devlink->sb_list, list) {
 			if (idx < start) {
 				idx++;
@@ -811,10 +814,13 @@ static int devlink_nl_cmd_sb_get_dumpit(struct sk_buff *msg,
 						 NETLINK_CB(cb->skb).portid,
 						 cb->nlh->nlmsg_seq,
 						 NLM_F_MULTI);
-			if (err)
+			if (err) {
+				mutex_unlock(&devlink->lock);
 				goto out;
+			}
 			idx++;
 		}
+		mutex_unlock(&devlink->lock);
 	}
 out:
 	mutex_unlock(&devlink_mutex);
@@ -935,14 +941,18 @@ static int devlink_nl_cmd_sb_pool_get_dumpit(struct sk_buff *msg,
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)) ||
 		    !devlink->ops || !devlink->ops->sb_pool_get)
 			continue;
+		mutex_lock(&devlink->lock);
 		list_for_each_entry(devlink_sb, &devlink->sb_list, list) {
 			err = __sb_pool_get_dumpit(msg, start, &idx, devlink,
 						   devlink_sb,
 						   NETLINK_CB(cb->skb).portid,
 						   cb->nlh->nlmsg_seq);
-			if (err && err != -EOPNOTSUPP)
+			if (err && err != -EOPNOTSUPP) {
+				mutex_unlock(&devlink->lock);
 				goto out;
+			}
 		}
+		mutex_unlock(&devlink->lock);
 	}
 out:
 	mutex_unlock(&devlink_mutex);
@@ -1123,22 +1133,24 @@ static int devlink_nl_cmd_sb_port_pool_get_dumpit(struct sk_buff *msg,
 	int err;
 
 	mutex_lock(&devlink_mutex);
-	mutex_lock(&devlink_port_mutex);
 	list_for_each_entry(devlink, &devlink_list, list) {
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)) ||
 		    !devlink->ops || !devlink->ops->sb_port_pool_get)
 			continue;
+		mutex_lock(&devlink->lock);
 		list_for_each_entry(devlink_sb, &devlink->sb_list, list) {
 			err = __sb_port_pool_get_dumpit(msg, start, &idx,
 							devlink, devlink_sb,
 							NETLINK_CB(cb->skb).portid,
 							cb->nlh->nlmsg_seq);
-			if (err && err != -EOPNOTSUPP)
+			if (err && err != -EOPNOTSUPP) {
+				mutex_unlock(&devlink->lock);
 				goto out;
+			}
 		}
+		mutex_unlock(&devlink->lock);
 	}
 out:
-	mutex_unlock(&devlink_port_mutex);
 	mutex_unlock(&devlink_mutex);
 
 	cb->args[0] = idx;
@@ -1347,23 +1359,26 @@ devlink_nl_cmd_sb_tc_pool_bind_get_dumpit(struct sk_buff *msg,
 	int err;
 
 	mutex_lock(&devlink_mutex);
-	mutex_lock(&devlink_port_mutex);
 	list_for_each_entry(devlink, &devlink_list, list) {
 		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)) ||
 		    !devlink->ops || !devlink->ops->sb_tc_pool_bind_get)
 			continue;
+
+		mutex_lock(&devlink->lock);
 		list_for_each_entry(devlink_sb, &devlink->sb_list, list) {
 			err = __sb_tc_pool_bind_get_dumpit(msg, start, &idx,
 							   devlink,
 							   devlink_sb,
 							   NETLINK_CB(cb->skb).portid,
 							   cb->nlh->nlmsg_seq);
-			if (err && err != -EOPNOTSUPP)
+			if (err && err != -EOPNOTSUPP) {
+				mutex_unlock(&devlink->lock);
 				goto out;
+			}
 		}
+		mutex_unlock(&devlink->lock);
 	}
 out:
-	mutex_unlock(&devlink_port_mutex);
 	mutex_unlock(&devlink_mutex);
 
 	cb->args[0] = idx;
@@ -2322,14 +2337,16 @@ static const struct genl_ops devlink_nl_ops[] = {
 		.doit = devlink_nl_cmd_port_split_doit,
 		.policy = devlink_nl_policy,
 		.flags = GENL_ADMIN_PERM,
-		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
+		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK |
+				  DEVLINK_NL_FLAG_NO_LOCK,
 	},
 	{
 		.cmd = DEVLINK_CMD_PORT_UNSPLIT,
 		.doit = devlink_nl_cmd_port_unsplit_doit,
 		.policy = devlink_nl_policy,
 		.flags = GENL_ADMIN_PERM,
-		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
+		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK |
+				  DEVLINK_NL_FLAG_NO_LOCK,
 	},
 	{
 		.cmd = DEVLINK_CMD_SB_GET,
@@ -2397,8 +2414,7 @@ static const struct genl_ops devlink_nl_ops[] = {
 		.policy = devlink_nl_policy,
 		.flags = GENL_ADMIN_PERM,
 		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK |
-				  DEVLINK_NL_FLAG_NEED_SB |
-				  DEVLINK_NL_FLAG_LOCK_PORTS,
+				  DEVLINK_NL_FLAG_NEED_SB,
 	},
 	{
 		.cmd = DEVLINK_CMD_SB_OCC_MAX_CLEAR,
@@ -2406,8 +2422,7 @@ static const struct genl_ops devlink_nl_ops[] = {
 		.policy = devlink_nl_policy,
 		.flags = GENL_ADMIN_PERM,
 		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK |
-				  DEVLINK_NL_FLAG_NEED_SB |
-				  DEVLINK_NL_FLAG_LOCK_PORTS,
+				  DEVLINK_NL_FLAG_NEED_SB,
 	},
 	{
 		.cmd = DEVLINK_CMD_ESWITCH_GET,
@@ -2488,6 +2503,7 @@ struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size)
 	INIT_LIST_HEAD(&devlink->port_list);
 	INIT_LIST_HEAD(&devlink->sb_list);
 	INIT_LIST_HEAD_RCU(&devlink->dpipe_table_list);
+	mutex_init(&devlink->lock);
 	return devlink;
 }
 EXPORT_SYMBOL_GPL(devlink_alloc);
@@ -2550,16 +2566,16 @@ int devlink_port_register(struct devlink *devlink,
 			  struct devlink_port *devlink_port,
 			  unsigned int port_index)
 {
-	mutex_lock(&devlink_port_mutex);
+	mutex_lock(&devlink->lock);
 	if (devlink_port_index_exists(devlink, port_index)) {
-		mutex_unlock(&devlink_port_mutex);
+		mutex_unlock(&devlink->lock);
 		return -EEXIST;
 	}
 	devlink_port->devlink = devlink;
 	devlink_port->index = port_index;
 	devlink_port->registered = true;
 	list_add_tail(&devlink_port->list, &devlink->port_list);
-	mutex_unlock(&devlink_port_mutex);
+	mutex_unlock(&devlink->lock);
 	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_NEW);
 	return 0;
 }
@@ -2572,10 +2588,12 @@ EXPORT_SYMBOL_GPL(devlink_port_register);
  */
 void devlink_port_unregister(struct devlink_port *devlink_port)
 {
+	struct devlink *devlink = devlink_port->devlink;
+
 	devlink_port_notify(devlink_port, DEVLINK_CMD_PORT_DEL);
-	mutex_lock(&devlink_port_mutex);
+	mutex_lock(&devlink->lock);
 	list_del(&devlink_port->list);
-	mutex_unlock(&devlink_port_mutex);
+	mutex_unlock(&devlink->lock);
 }
 EXPORT_SYMBOL_GPL(devlink_port_unregister);
 
@@ -2651,7 +2669,7 @@ int devlink_sb_register(struct devlink *devlink, unsigned int sb_index,
 	struct devlink_sb *devlink_sb;
 	int err = 0;
 
-	mutex_lock(&devlink_mutex);
+	mutex_lock(&devlink->lock);
 	if (devlink_sb_index_exists(devlink, sb_index)) {
 		err = -EEXIST;
 		goto unlock;
@@ -2670,7 +2688,7 @@ int devlink_sb_register(struct devlink *devlink, unsigned int sb_index,
 	devlink_sb->egress_tc_count = egress_tc_count;
 	list_add_tail(&devlink_sb->list, &devlink->sb_list);
 unlock:
-	mutex_unlock(&devlink_mutex);
+	mutex_unlock(&devlink->lock);
 	return err;
 }
 EXPORT_SYMBOL_GPL(devlink_sb_register);
@@ -2679,11 +2697,11 @@ void devlink_sb_unregister(struct devlink *devlink, unsigned int sb_index)
 {
 	struct devlink_sb *devlink_sb;
 
-	mutex_lock(&devlink_mutex);
+	mutex_lock(&devlink->lock);
 	devlink_sb = devlink_sb_get_by_index(devlink, sb_index);
 	WARN_ON(!devlink_sb);
 	list_del(&devlink_sb->list);
-	mutex_unlock(&devlink_mutex);
+	mutex_unlock(&devlink->lock);
 	kfree(devlink_sb);
 }
 EXPORT_SYMBOL_GPL(devlink_sb_unregister);
@@ -2699,9 +2717,9 @@ EXPORT_SYMBOL_GPL(devlink_sb_unregister);
 int devlink_dpipe_headers_register(struct devlink *devlink,
 				   struct devlink_dpipe_headers *dpipe_headers)
 {
-	mutex_lock(&devlink_mutex);
+	mutex_lock(&devlink->lock);
 	devlink->dpipe_headers = dpipe_headers;
-	mutex_unlock(&devlink_mutex);
+	mutex_unlock(&devlink->lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(devlink_dpipe_headers_register);
@@ -2715,9 +2733,9 @@ EXPORT_SYMBOL_GPL(devlink_dpipe_headers_register);
  */
 void devlink_dpipe_headers_unregister(struct devlink *devlink)
 {
-	mutex_lock(&devlink_mutex);
+	mutex_lock(&devlink->lock);
 	devlink->dpipe_headers = NULL;
-	mutex_unlock(&devlink_mutex);
+	mutex_unlock(&devlink->lock);
 }
 EXPORT_SYMBOL_GPL(devlink_dpipe_headers_unregister);
 
@@ -2783,9 +2801,9 @@ int devlink_dpipe_table_register(struct devlink *devlink,
 	table->priv = priv;
 	table->counter_control_extern = counter_control_extern;
 
-	mutex_lock(&devlink_mutex);
+	mutex_lock(&devlink->lock);
 	list_add_tail_rcu(&table->list, &devlink->dpipe_table_list);
-	mutex_unlock(&devlink_mutex);
+	mutex_unlock(&devlink->lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(devlink_dpipe_table_register);
@@ -2801,17 +2819,17 @@ void devlink_dpipe_table_unregister(struct devlink *devlink,
 {
 	struct devlink_dpipe_table *table;
 
-	mutex_lock(&devlink_mutex);
+	mutex_lock(&devlink->lock);
 	table = devlink_dpipe_table_find(&devlink->dpipe_table_list,
 					 table_name);
 	if (!table)
 		goto unlock;
 	list_del_rcu(&table->list);
-	mutex_unlock(&devlink_mutex);
+	mutex_unlock(&devlink->lock);
 	kfree_rcu(table, rcu);
 	return;
 unlock:
-	mutex_unlock(&devlink_mutex);
+	mutex_unlock(&devlink->lock);
 }
 EXPORT_SYMBOL_GPL(devlink_dpipe_table_unregister);
 
-- 
2.9.5