devlink: Allow taking device lock in pre_doit operations

Introduce a new private flag ('DEVLINK_NL_FLAG_NEED_DEV_LOCK') to allow
netlink commands to specify that they need to acquire the device lock in
their pre_doit operation and release it in their post_doit operation.

The reload command will use this flag in the subsequent patch.

No functional changes intended.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/devlink/devl_internal.h

@@ -152,7 +152,8 @@ typedef int devlink_nl_dump_one_func_t(struct sk_buff *msg,
 				       int flags);
 
 struct devlink *
-devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs);
+devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs,
+			    bool dev_lock);
 
 int devlink_nl_dumpit(struct sk_buff *msg, struct netlink_callback *cb,
 		      devlink_nl_dump_one_func_t *dump_one);

net/devlink/health.c

@@ -1151,7 +1151,8 @@ devlink_health_reporter_get_from_cb_lock(struct netlink_callback *cb)
 	struct nlattr **attrs = info->attrs;
 	struct devlink *devlink;
 
-	devlink = devlink_get_from_attrs_lock(sock_net(cb->skb->sk), attrs);
+	devlink = devlink_get_from_attrs_lock(sock_net(cb->skb->sk), attrs,
+					      false);
 	if (IS_ERR(devlink))
 		return NULL;
 

net/devlink/netlink.c

@@ -11,6 +11,7 @@
 
 #define DEVLINK_NL_FLAG_NEED_PORT		BIT(0)
 #define DEVLINK_NL_FLAG_NEED_DEVLINK_OR_PORT	BIT(1)
+#define DEVLINK_NL_FLAG_NEED_DEV_LOCK		BIT(2)
 
 static const struct genl_multicast_group devlink_nl_mcgrps[] = {
 	[DEVLINK_MCGRP_CONFIG] = { .name = DEVLINK_GENL_MCGRP_CONFIG_NAME },
@@ -64,7 +65,8 @@ int devlink_nl_msg_reply_and_new(struct sk_buff **msg, struct genl_info *info)
 }
 
 struct devlink *
-devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs)
+devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs,
+			    bool dev_lock)
 {
 	struct devlink *devlink;
 	unsigned long index;
@@ -78,12 +80,12 @@ devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs)
 	devname = nla_data(attrs[DEVLINK_ATTR_DEV_NAME]);
 
 	devlinks_xa_for_each_registered_get(net, index, devlink) {
-		devl_lock(devlink);
+		devl_dev_lock(devlink, dev_lock);
 		if (devl_is_registered(devlink) &&
 		    strcmp(devlink->dev->bus->name, busname) == 0 &&
 		    strcmp(dev_name(devlink->dev), devname) == 0)
 			return devlink;
-		devl_unlock(devlink);
+		devl_dev_unlock(devlink, dev_lock);
 		devlink_put(devlink);
 	}
 
@@ -93,11 +95,13 @@ devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs)
 static int __devlink_nl_pre_doit(struct sk_buff *skb, struct genl_info *info,
 				 u8 flags)
 {
+	bool dev_lock = flags & DEVLINK_NL_FLAG_NEED_DEV_LOCK;
 	struct devlink_port *devlink_port;
 	struct devlink *devlink;
 	int err;
 
-	devlink = devlink_get_from_attrs_lock(genl_info_net(info), info->attrs);
+	devlink = devlink_get_from_attrs_lock(genl_info_net(info), info->attrs,
+					      dev_lock);
 	if (IS_ERR(devlink))
 		return PTR_ERR(devlink);
 
@@ -117,7 +121,7 @@ static int __devlink_nl_pre_doit(struct sk_buff *skb, struct genl_info *info,
 	return 0;
 
 unlock:
-	devl_unlock(devlink);
+	devl_dev_unlock(devlink, dev_lock);
 	devlink_put(devlink);
 	return err;
 }
@@ -144,10 +148,11 @@ int devlink_nl_pre_doit_port_optional(const struct genl_split_ops *ops,
 static void __devlink_nl_post_doit(struct sk_buff *skb, struct genl_info *info,
 				   u8 flags)
 {
+	bool dev_lock = flags & DEVLINK_NL_FLAG_NEED_DEV_LOCK;
 	struct devlink *devlink;
 
 	devlink = info->user_ptr[0];
-	devl_unlock(devlink);
+	devl_dev_unlock(devlink, dev_lock);
 	devlink_put(devlink);
 }
 
@@ -165,7 +170,7 @@ static int devlink_nl_inst_single_dumpit(struct sk_buff *msg,
 	struct devlink *devlink;
 	int err;
 
-	devlink = devlink_get_from_attrs_lock(sock_net(msg->sk), attrs);
+	devlink = devlink_get_from_attrs_lock(sock_net(msg->sk), attrs, false);
 	if (IS_ERR(devlink))
 		return PTR_ERR(devlink);
 	err = dump_one(msg, devlink, cb, flags | NLM_F_DUMP_FILTERED);

net/devlink/region.c

@@ -883,7 +883,8 @@ int devlink_nl_region_read_dumpit(struct sk_buff *skb,
 
 	start_offset = state->start_offset;
 
-	devlink = devlink_get_from_attrs_lock(sock_net(cb->skb->sk), attrs);
+	devlink = devlink_get_from_attrs_lock(sock_net(cb->skb->sk), attrs,
+					      false);
 	if (IS_ERR(devlink))
 		return PTR_ERR(devlink);