Merge branch 'devlink-unregister'

Jakub Kicinski says:

====================
devlink: remove the wait-for-references on unregister

Move the registration and unregistration of the devlink instances
under their instance locks. Don't perform the netdev-style wait
for all references when unregistering the instance.

Instead the devlink instance refcount will only ensure that
the memory of the instance is not freed. All places which acquire
access to devlink instances via a reference must check that the
instance is still registered under the instance lock.

This fixes the problem of the netdev code accessing devlink
instances before they are registered.

RFC: https://lore.kernel.org/all/20221217011953.152487-1-kuba@kernel.org/
 - rewrite the cover letter
 - rewrite the commit message for patch 1
 - un-export and rename devl_is_alive
 - squash the netdevsim patches
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 5 deletions

diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c
index a552e723f4a6..b5b8ac6db2d1 100644
--- a/net/devlink/netlink.c
+++ b/net/devlink/netlink.c
@@ -82,7 +82,8 @@ static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = {
 	[DEVLINK_ATTR_REGION_DIRECT] = { .type = NLA_FLAG },
 };
 
-struct devlink *devlink_get_from_attrs(struct net *net, struct nlattr **attrs)
+struct devlink *
+devlink_get_from_attrs_lock(struct net *net, struct nlattr **attrs)
 {
 	struct devlink *devlink;
 	unsigned long index;
@@ -96,9 +97,12 @@ struct devlink *devlink_get_from_attrs(struct net *net, struct nlattr **attrs)
 	devname = nla_data(attrs[DEVLINK_ATTR_DEV_NAME]);
 
 	devlinks_xa_for_each_registered_get(net, index, devlink) {
-		if (strcmp(devlink->dev->bus->name, busname) == 0 &&
+		devl_lock(devlink);
+		if (devl_is_registered(devlink) &&
+		    strcmp(devlink->dev->bus->name, busname) == 0 &&
 		    strcmp(dev_name(devlink->dev), devname) == 0)
 			return devlink;
+		devl_unlock(devlink);
 		devlink_put(devlink);
 	}
 
@@ -113,10 +117,10 @@ static int devlink_nl_pre_doit(const struct genl_split_ops *ops,
 	struct devlink *devlink;
 	int err;
 
-	devlink = devlink_get_from_attrs(genl_info_net(info), info->attrs);
+	devlink = devlink_get_from_attrs_lock(genl_info_net(info), info->attrs);
 	if (IS_ERR(devlink))
 		return PTR_ERR(devlink);
-	devl_lock(devlink);
+
 	info->user_ptr[0] = devlink;
 	if (ops->internal_flags & DEVLINK_NL_FLAG_NEED_PORT) {
 		devlink_port = devlink_port_get_from_info(devlink, info);
@@ -208,7 +212,12 @@ int devlink_nl_instance_iter_dump(struct sk_buff *msg,
 
 	devlink_dump_for_each_instance_get(msg, state, devlink) {
 		devl_lock(devlink);
-		err = cmd->dump_one(msg, devlink, cb);
+
+		if (devl_is_registered(devlink))
+			err = cmd->dump_one(msg, devlink, cb);
+		else
+			err = 0;
+
 		devl_unlock(devlink);
 		devlink_put(devlink);