Merge branch 'devlink-code-split-and-structured-instance-walk'

Jakub Kicinski says:

====================
devlink: code split and structured instance walk

Split devlink.c into a handful of files, trying to keep the "core"
code away from all the command-specific implementations.
The core code has been quite scattered until now. Going forward we can
consider using a source file per-subobject, I think that it's quite
beneficial to newcomers (based on relative ease with which folks
contribute to ethtool vs devlink). But this series doesn't split
everything out, yet - partially due to backporting concerns,
but mostly due to lack of time. Bulk of the netlink command
handling is left in a leftover.c file.

Introduce a context structure for dumps, and use it to store
the devlink instance ID of the last dumped devlink instance.
This means we don't have to restart the walk from 0 each time.

Finally - introduce a "structured walk". A centralized dump handler
in devlink/netlink.c which walks the devlink instances, deals with
refcounting/locking, simplifying the per-object implementations quite
a bit. Inspired by the ethtool code.

v1: https://lore.kernel.org/all/20230104041636.226398-1-kuba@kernel.org/
RFC: https://lore.kernel.org/all/20221215020155.1619839-1-kuba@kernel.org/
====================

Link: https://lore.kernel.org/r/20230105040531.353563-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

MAINTAINERS

@@ -6099,7 +6099,7 @@ S:	Supported
 F:	Documentation/networking/devlink
 F:	include/net/devlink.h
 F:	include/uapi/linux/devlink.h
-F:	net/core/devlink.c
+F:	net/devlink/
 
 DH ELECTRONICS IMX6 DHCOM/DHCOR BOARD SUPPORT
 M:	Christoph Niedermaier <cniedermaier@dh-electronics.com>

include/linux/netlink.h

@@ -263,6 +263,10 @@ struct netlink_callback {
 	};
 };
 
+#define NL_ASSET_DUMP_CTX_FITS(type_name)				\
+	BUILD_BUG_ON(sizeof(type_name) >				\
+		     sizeof_field(struct netlink_callback, ctx))
+
 struct netlink_notify {
 	struct net *net;
 	u32 portid;

net/Makefile

@@ -23,6 +23,7 @@ obj-$(CONFIG_BPFILTER)		+= bpfilter/
 obj-$(CONFIG_PACKET)		+= packet/
 obj-$(CONFIG_NET_KEY)		+= key/
 obj-$(CONFIG_BRIDGE)		+= bridge/
+obj-$(CONFIG_NET_DEVLINK)	+= devlink/
 obj-$(CONFIG_NET_DSA)		+= dsa/
 obj-$(CONFIG_ATALK)		+= appletalk/
 obj-$(CONFIG_X25)		+= x25/

net/core/Makefile

@@ -33,7 +33,6 @@ obj-$(CONFIG_LWTUNNEL) += lwtunnel.o
 obj-$(CONFIG_LWTUNNEL_BPF) += lwt_bpf.o
 obj-$(CONFIG_DST_CACHE) += dst_cache.o
 obj-$(CONFIG_HWBM) += hwbm.o
-obj-$(CONFIG_NET_DEVLINK) += devlink.o
 obj-$(CONFIG_GRO_CELLS) += gro_cells.o
 obj-$(CONFIG_FAILOVER) += failover.o
 obj-$(CONFIG_NET_SOCK_MSG) += skmsg.o

net/devlink/Makefile

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y := leftover.o core.o netlink.o

net/devlink/core.c

@@ -0,0 +1,345 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2016 Jiri Pirko <jiri@mellanox.com>
+ */
+
+#include <net/genetlink.h>
+
+#include "devl_internal.h"
+
+DEFINE_XARRAY_FLAGS(devlinks, XA_FLAGS_ALLOC);
+
+void *devlink_priv(struct devlink *devlink)
+{
+	return &devlink->priv;
+}
+EXPORT_SYMBOL_GPL(devlink_priv);
+
+struct devlink *priv_to_devlink(void *priv)
+{
+	return container_of(priv, struct devlink, priv);
+}
+EXPORT_SYMBOL_GPL(priv_to_devlink);
+
+struct device *devlink_to_dev(const struct devlink *devlink)
+{
+	return devlink->dev;
+}
+EXPORT_SYMBOL_GPL(devlink_to_dev);
+
+struct net *devlink_net(const struct devlink *devlink)
+{
+	return read_pnet(&devlink->_net);
+}
+EXPORT_SYMBOL_GPL(devlink_net);
+
+void devl_assert_locked(struct devlink *devlink)
+{
+	lockdep_assert_held(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_assert_locked);
+
+#ifdef CONFIG_LOCKDEP
+/* For use in conjunction with LOCKDEP only e.g. rcu_dereference_protected() */
+bool devl_lock_is_held(struct devlink *devlink)
+{
+	return lockdep_is_held(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_lock_is_held);
+#endif
+
+void devl_lock(struct devlink *devlink)
+{
+	mutex_lock(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_lock);
+
+int devl_trylock(struct devlink *devlink)
+{
+	return mutex_trylock(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_trylock);
+
+void devl_unlock(struct devlink *devlink)
+{
+	mutex_unlock(&devlink->lock);
+}
+EXPORT_SYMBOL_GPL(devl_unlock);
+
+struct devlink *__must_check devlink_try_get(struct devlink *devlink)
+{
+	if (refcount_inc_not_zero(&devlink->refcount))
+		return devlink;
+	return NULL;
+}
+
+static void __devlink_put_rcu(struct rcu_head *head)
+{
+	struct devlink *devlink = container_of(head, struct devlink, rcu);
+
+	complete(&devlink->comp);
+}
+
+void devlink_put(struct devlink *devlink)
+{
+	if (refcount_dec_and_test(&devlink->refcount))
+		/* Make sure unregister operation that may await the completion
+		 * is unblocked only after all users are after the end of
+		 * RCU grace period.
+		 */
+		call_rcu(&devlink->rcu, __devlink_put_rcu);
+}
+
+struct devlink *
+devlinks_xa_find_get(struct net *net, unsigned long *indexp,
+		     void * (*xa_find_fn)(struct xarray *, unsigned long *,
+					  unsigned long, xa_mark_t))
+{
+	struct devlink *devlink;
+
+	rcu_read_lock();
+retry:
+	devlink = xa_find_fn(&devlinks, indexp, ULONG_MAX, DEVLINK_REGISTERED);
+	if (!devlink)
+		goto unlock;
+
+	/* In case devlink_unregister() was already called and "unregistering"
+	 * mark was set, do not allow to get a devlink reference here.
+	 * This prevents live-lock of devlink_unregister() wait for completion.
+	 */
+	if (xa_get_mark(&devlinks, *indexp, DEVLINK_UNREGISTERING))
+		goto retry;
+
+	/* For a possible retry, the xa_find_after() should be always used */
+	xa_find_fn = xa_find_after;
+	if (!devlink_try_get(devlink))
+		goto retry;
+	if (!net_eq(devlink_net(devlink), net)) {
+		devlink_put(devlink);
+		goto retry;
+	}
+unlock:
+	rcu_read_unlock();
+	return devlink;
+}
+
+struct devlink *
+devlinks_xa_find_get_first(struct net *net, unsigned long *indexp)
+{
+	return devlinks_xa_find_get(net, indexp, xa_find);
+}
+
+struct devlink *
+devlinks_xa_find_get_next(struct net *net, unsigned long *indexp)
+{
+	return devlinks_xa_find_get(net, indexp, xa_find_after);
+}
+
+/**
+ *	devlink_set_features - Set devlink supported features
+ *
+ *	@devlink: devlink
+ *	@features: devlink support features
+ *
+ *	This interface allows us to set reload ops separatelly from
+ *	the devlink_alloc.
+ */
+void devlink_set_features(struct devlink *devlink, u64 features)
+{
+	ASSERT_DEVLINK_NOT_REGISTERED(devlink);
+
+	WARN_ON(features & DEVLINK_F_RELOAD &&
+		!devlink_reload_supported(devlink->ops));
+	devlink->features = features;
+}
+EXPORT_SYMBOL_GPL(devlink_set_features);
+
+/**
+ *	devlink_register - Register devlink instance
+ *
+ *	@devlink: devlink
+ */
+void devlink_register(struct devlink *devlink)
+{
+	ASSERT_DEVLINK_NOT_REGISTERED(devlink);
+	/* Make sure that we are in .probe() routine */
+
+	xa_set_mark(&devlinks, devlink->index, DEVLINK_REGISTERED);
+	devlink_notify_register(devlink);
+}
+EXPORT_SYMBOL_GPL(devlink_register);
+
+/**
+ *	devlink_unregister - Unregister devlink instance
+ *
+ *	@devlink: devlink
+ */
+void devlink_unregister(struct devlink *devlink)
+{
+	ASSERT_DEVLINK_REGISTERED(devlink);
+	/* Make sure that we are in .remove() routine */
+
+	xa_set_mark(&devlinks, devlink->index, DEVLINK_UNREGISTERING);
+	devlink_put(devlink);
+	wait_for_completion(&devlink->comp);
+
+	devlink_notify_unregister(devlink);
+	xa_clear_mark(&devlinks, devlink->index, DEVLINK_REGISTERED);
+	xa_clear_mark(&devlinks, devlink->index, DEVLINK_UNREGISTERING);
+}
+EXPORT_SYMBOL_GPL(devlink_unregister);
+
+/**
+ *	devlink_alloc_ns - Allocate new devlink instance resources
+ *	in specific namespace
+ *
+ *	@ops: ops
+ *	@priv_size: size of user private data
+ *	@net: net namespace
+ *	@dev: parent device
+ *
+ *	Allocate new devlink instance resources, including devlink index
+ *	and name.
+ */
+struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
+				 size_t priv_size, struct net *net,
+				 struct device *dev)
+{
+	struct devlink *devlink;
+	static u32 last_id;
+	int ret;
+
+	WARN_ON(!ops || !dev);
+	if (!devlink_reload_actions_valid(ops))
+		return NULL;
+
+	devlink = kzalloc(sizeof(*devlink) + priv_size, GFP_KERNEL);
+	if (!devlink)
+		return NULL;
+
+	ret = xa_alloc_cyclic(&devlinks, &devlink->index, devlink, xa_limit_31b,
+			      &last_id, GFP_KERNEL);
+	if (ret < 0)
+		goto err_xa_alloc;
+
+	devlink->netdevice_nb.notifier_call = devlink_port_netdevice_event;
+	ret = register_netdevice_notifier_net(net, &devlink->netdevice_nb);
+	if (ret)
+		goto err_register_netdevice_notifier;
+
+	devlink->dev = dev;
+	devlink->ops = ops;
+	xa_init_flags(&devlink->ports, XA_FLAGS_ALLOC);
+	xa_init_flags(&devlink->snapshot_ids, XA_FLAGS_ALLOC);
+	write_pnet(&devlink->_net, net);
+	INIT_LIST_HEAD(&devlink->rate_list);
+	INIT_LIST_HEAD(&devlink->linecard_list);
+	INIT_LIST_HEAD(&devlink->sb_list);
+	INIT_LIST_HEAD_RCU(&devlink->dpipe_table_list);
+	INIT_LIST_HEAD(&devlink->resource_list);
+	INIT_LIST_HEAD(&devlink->param_list);
+	INIT_LIST_HEAD(&devlink->region_list);
+	INIT_LIST_HEAD(&devlink->reporter_list);
+	INIT_LIST_HEAD(&devlink->trap_list);
+	INIT_LIST_HEAD(&devlink->trap_group_list);
+	INIT_LIST_HEAD(&devlink->trap_policer_list);
+	lockdep_register_key(&devlink->lock_key);
+	mutex_init(&devlink->lock);
+	lockdep_set_class(&devlink->lock, &devlink->lock_key);
+	mutex_init(&devlink->reporters_lock);
+	mutex_init(&devlink->linecards_lock);
+	refcount_set(&devlink->refcount, 1);
+	init_completion(&devlink->comp);
+
+	return devlink;
+
+err_register_netdevice_notifier:
+	xa_erase(&devlinks, devlink->index);
+err_xa_alloc:
+	kfree(devlink);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(devlink_alloc_ns);
+
+/**
+ *	devlink_free - Free devlink instance resources
+ *
+ *	@devlink: devlink
+ */
+void devlink_free(struct devlink *devlink)
+{
+	ASSERT_DEVLINK_NOT_REGISTERED(devlink);
+
+	mutex_destroy(&devlink->linecards_lock);
+	mutex_destroy(&devlink->reporters_lock);
+	mutex_destroy(&devlink->lock);
+	lockdep_unregister_key(&devlink->lock_key);
+	WARN_ON(!list_empty(&devlink->trap_policer_list));
+	WARN_ON(!list_empty(&devlink->trap_group_list));
+	WARN_ON(!list_empty(&devlink->trap_list));
+	WARN_ON(!list_empty(&devlink->reporter_list));
+	WARN_ON(!list_empty(&devlink->region_list));
+	WARN_ON(!list_empty(&devlink->param_list));
+	WARN_ON(!list_empty(&devlink->resource_list));
+	WARN_ON(!list_empty(&devlink->dpipe_table_list));
+	WARN_ON(!list_empty(&devlink->sb_list));
+	WARN_ON(!list_empty(&devlink->rate_list));
+	WARN_ON(!list_empty(&devlink->linecard_list));
+	WARN_ON(!xa_empty(&devlink->ports));
+
+	xa_destroy(&devlink->snapshot_ids);
+	xa_destroy(&devlink->ports);
+
+	WARN_ON_ONCE(unregister_netdevice_notifier_net(devlink_net(devlink),
+						       &devlink->netdevice_nb));
+
+	xa_erase(&devlinks, devlink->index);
+
+	kfree(devlink);
+}
+EXPORT_SYMBOL_GPL(devlink_free);
+
+static void __net_exit devlink_pernet_pre_exit(struct net *net)
+{
+	struct devlink *devlink;
+	u32 actions_performed;
+	unsigned long index;
+	int err;
+
+	/* In case network namespace is getting destroyed, reload
+	 * all devlink instances from this namespace into init_net.
+	 */
+	devlinks_xa_for_each_registered_get(net, index, devlink) {
+		WARN_ON(!(devlink->features & DEVLINK_F_RELOAD));
+		mutex_lock(&devlink->lock);
+		err = devlink_reload(devlink, &init_net,
+				     DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
+				     DEVLINK_RELOAD_LIMIT_UNSPEC,
+				     &actions_performed, NULL);
+		mutex_unlock(&devlink->lock);
+		if (err && err != -EOPNOTSUPP)
+			pr_warn("Failed to reload devlink instance into init_net\n");
+		devlink_put(devlink);
+	}
+}
+
+static struct pernet_operations devlink_pernet_ops __net_initdata = {
+	.pre_exit = devlink_pernet_pre_exit,
+};
+
+static int __init devlink_init(void)
+{
+	int err;
+
+	err = genl_register_family(&devlink_nl_family);
+	if (err)
+		goto out;
+	err = register_pernet_subsys(&devlink_pernet_ops);
+
+out:
+	WARN_ON(err);
+	return err;
+}
+
+subsys_initcall(devlink_init);