netdevsim: Add simple FIB resource controller via devlink

Add devlink support to netdevsim and use it to implement a simple,
profile based resource controller. Only one controller is needed
per namespace, so the first netdevsim netdevice in a namespace
registers with devlink. If that device is deleted, the resource
settings are deleted.

The resource controller allows a user to limit the number of IPv4 and
IPv6 FIB entries and FIB rules. The resource paths are:
    /IPv4
    /IPv4/fib
    /IPv4/fib-rules
    /IPv6
    /IPv6/fib
    /IPv6/fib-rules

The IPv4 and IPv6 top level resources are unlimited in size and can not
be changed. From there, the number of FIB entries and FIB rule entries
are unlimited by default. A user can specify a limit for the fib and
fib-rules resources:

    $ devlink resource set netdevsim/netdevsim0 path /IPv4/fib size 96
    $ devlink resource set netdevsim/netdevsim0 path /IPv4/fib-rules size 16
    $ devlink resource set netdevsim/netdevsim0 path /IPv6/fib size 64
    $ devlink resource set netdevsim/netdevsim0 path /IPv6/fib-rules size 16
    $ devlink dev reload netdevsim/netdevsim0

such that the number of rules or routes is limited (96 ipv4 routes in the
example above):
    $ for n in $(seq 1 32); do ip ro add 10.99.$n.0/24 dev eth1; done
    Error: netdevsim: Exceeded number of supported fib entries.

    $ devlink resource show netdevsim/netdevsim0
    netdevsim/netdevsim0:
      name IPv4 size unlimited unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables non
        resources:
          name fib size 96 occ 96 unit entry size_min 0 size_max unlimited size_gran 1 dpipe_tables
    ...

With this template in place for resource management, it is fairly trivial
to extend and shows one way to implement a simple counter based resource
controller typical of network profiles.

Currently, devlink only supports initial namespace. Code is in place to
adapt netdevsim to a per namespace controller once the network namespace
issues are resolved.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 263 insertions, 0 deletions

diff --git a/drivers/net/netdevsim/fib.c b/drivers/net/netdevsim/fib.c
new file mode 100644
index 000000000000..0d105bafa261
--- /dev/null
+++ b/drivers/net/netdevsim/fib.c
@@ -0,0 +1,263 @@
+/*
+ * Copyright (c) 2018 Cumulus Networks. All rights reserved.
+ * Copyright (c) 2018 David Ahern <dsa@cumulusnetworks.com>
+ *
+ * This software is licensed under the GNU General License Version 2,
+ * June 1991 as shown in the file COPYING in the top-level directory of this
+ * source tree.
+ *
+ * THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
+ * WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE
+ * OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME
+ * THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+ */
+
+#include <net/fib_notifier.h>
+#include <net/ip_fib.h>
+#include <net/ip6_fib.h>
+#include <net/fib_rules.h>
+#include <net/netns/generic.h>
+
+#include "netdevsim.h"
+
+struct nsim_fib_entry {
+	u64 max;
+	u64 num;
+};
+
+struct nsim_per_fib_data {
+	struct nsim_fib_entry fib;
+	struct nsim_fib_entry rules;
+};
+
+struct nsim_fib_data {
+	struct nsim_per_fib_data ipv4;
+	struct nsim_per_fib_data ipv6;
+};
+
+static unsigned int nsim_fib_net_id;
+
+u64 nsim_fib_get_val(struct net *net, enum nsim_resource_id res_id, bool max)
+{
+	struct nsim_fib_data *fib_data = net_generic(net, nsim_fib_net_id);
+	struct nsim_fib_entry *entry;
+
+	switch (res_id) {
+	case NSIM_RESOURCE_IPV4_FIB:
+		entry = &fib_data->ipv4.fib;
+		break;
+	case NSIM_RESOURCE_IPV4_FIB_RULES:
+		entry = &fib_data->ipv4.rules;
+		break;
+	case NSIM_RESOURCE_IPV6_FIB:
+		entry = &fib_data->ipv6.fib;
+		break;
+	case NSIM_RESOURCE_IPV6_FIB_RULES:
+		entry = &fib_data->ipv6.rules;
+		break;
+	default:
+		return 0;
+	}
+
+	return max ? entry->max : entry->num;
+}
+
+int nsim_fib_set_max(struct net *net, enum nsim_resource_id res_id, u64 val)
+{
+	struct nsim_fib_data *fib_data = net_generic(net, nsim_fib_net_id);
+	struct nsim_fib_entry *entry;
+	int err = 0;
+
+	switch (res_id) {
+	case NSIM_RESOURCE_IPV4_FIB:
+		entry = &fib_data->ipv4.fib;
+		break;
+	case NSIM_RESOURCE_IPV4_FIB_RULES:
+		entry = &fib_data->ipv4.rules;
+		break;
+	case NSIM_RESOURCE_IPV6_FIB:
+		entry = &fib_data->ipv6.fib;
+		break;
+	case NSIM_RESOURCE_IPV6_FIB_RULES:
+		entry = &fib_data->ipv6.rules;
+		break;
+	default:
+		return 0;
+	}
+
+	/* not allowing a new max to be less than curren occupancy
+	 * --> no means of evicting entries
+	 */
+	if (val < entry->num)
+		err = -EINVAL;
+	else
+		entry->max = val;
+
+	return err;
+}
+
+static int nsim_fib_rule_account(struct nsim_fib_entry *entry, bool add,
+				 struct netlink_ext_ack *extack)
+{
+	int err = 0;
+
+	if (add) {
+		if (entry->num < entry->max) {
+			entry->num++;
+		} else {
+			err = -ENOSPC;
+			NL_SET_ERR_MSG_MOD(extack, "Exceeded number of supported fib rule entries");
+		}
+	} else {
+		entry->num--;
+	}
+
+	return err;
+}
+
+static int nsim_fib_rule_event(struct fib_notifier_info *info, bool add)
+{
+	struct nsim_fib_data *data = net_generic(info->net, nsim_fib_net_id);
+	struct netlink_ext_ack *extack = info->extack;
+	int err = 0;
+
+	switch (info->family) {
+	case AF_INET:
+		err = nsim_fib_rule_account(&data->ipv4.rules, add, extack);
+		break;
+	case AF_INET6:
+		err = nsim_fib_rule_account(&data->ipv6.rules, add, extack);
+		break;
+	}
+
+	return err;
+}
+
+static int nsim_fib_account(struct nsim_fib_entry *entry, bool add,
+			    struct netlink_ext_ack *extack)
+{
+	int err = 0;
+
+	if (add) {
+		if (entry->num < entry->max) {
+			entry->num++;
+		} else {
+			err = -ENOSPC;
+			NL_SET_ERR_MSG_MOD(extack, "Exceeded number of supported fib entries");
+		}
+	} else {
+		entry->num--;
+	}
+
+	return err;
+}
+
+static int nsim_fib_event(struct fib_notifier_info *info, bool add)
+{
+	struct nsim_fib_data *data = net_generic(info->net, nsim_fib_net_id);
+	struct netlink_ext_ack *extack = info->extack;
+	int err = 0;
+
+	switch (info->family) {
+	case AF_INET:
+		err = nsim_fib_account(&data->ipv4.fib, add, extack);
+		break;
+	case AF_INET6:
+		err = nsim_fib_account(&data->ipv6.fib, add, extack);
+		break;
+	}
+
+	return err;
+}
+
+static int nsim_fib_event_nb(struct notifier_block *nb, unsigned long event,
+			     void *ptr)
+{
+	struct fib_notifier_info *info = ptr;
+	int err = 0;
+
+	switch (event) {
+	case FIB_EVENT_RULE_ADD: /* fall through */
+	case FIB_EVENT_RULE_DEL:
+		err = nsim_fib_rule_event(info, event == FIB_EVENT_RULE_ADD);
+		break;
+
+	case FIB_EVENT_ENTRY_ADD:  /* fall through */
+	case FIB_EVENT_ENTRY_DEL:
+		err = nsim_fib_event(info, event == FIB_EVENT_ENTRY_ADD);
+		break;
+	}
+
+	return notifier_from_errno(err);
+}
+
+/* inconsistent dump, trying again */
+static void nsim_fib_dump_inconsistent(struct notifier_block *nb)
+{
+	struct nsim_fib_data *data;
+	struct net *net;
+
+	rcu_read_lock();
+	for_each_net_rcu(net) {
+		data = net_generic(net, nsim_fib_net_id);
+
+		data->ipv4.fib.num = 0ULL;
+		data->ipv4.rules.num = 0ULL;
+
+		data->ipv6.fib.num = 0ULL;
+		data->ipv6.rules.num = 0ULL;
+	}
+	rcu_read_unlock();
+}
+
+static struct notifier_block nsim_fib_nb = {
+	.notifier_call = nsim_fib_event_nb,
+};
+
+/* Initialize per network namespace state */
+static int __net_init nsim_fib_netns_init(struct net *net)
+{
+	struct nsim_fib_data *data = net_generic(net, nsim_fib_net_id);
+
+	data->ipv4.fib.max = (u64)-1;
+	data->ipv4.rules.max = (u64)-1;
+
+	data->ipv6.fib.max = (u64)-1;
+	data->ipv6.rules.max = (u64)-1;
+
+	return 0;
+}
+
+static struct pernet_operations nsim_fib_net_ops __net_initdata = {
+	.init = nsim_fib_netns_init,
+	.id   = &nsim_fib_net_id,
+	.size = sizeof(struct nsim_fib_data),
+};
+
+void nsim_fib_exit(void)
+{
+	unregister_pernet_subsys(&nsim_fib_net_ops);
+	unregister_fib_notifier(&nsim_fib_nb);
+}
+
+int nsim_fib_init(void)
+{
+	int err;
+
+	err = register_pernet_subsys(&nsim_fib_net_ops);
+	if (err < 0) {
+		pr_err("Failed to register pernet subsystem\n");
+		goto err_out;
+	}
+
+	err = register_fib_notifier(&nsim_fib_nb, nsim_fib_dump_inconsistent);
+	if (err < 0) {
+		pr_err("Failed to register fib notifier\n");
+		goto err_out;
+	}
+
+err_out:
+	return err;
+}