mlxsw: spectrum_router: Periodically update the kernel's neigh table

As previously explained, the driver should periodically poll the device
for neighbours activity according to the configured DELAY_PROBE_TIME.
This will prevent active neighbours from staying in STALE state for long
periods of time.

During init configure the polling interval according to the
DELAY_PROBE_TIME used in the default table. In addition, register a
netevent notification block, so that the interval is updated whenever
DELAY_PROBE_TIME changes.

Using the computed interval schedule a delayed work, which will update
the kernel via neigh_event_send() on any active neighbour since the last
delayed work.

Signed-off-by: Yotam Gigi <yotamg@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 194 insertions, 2 deletions

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
index 734c5baffaf1..9c2a60f01517 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
@@ -214,6 +214,10 @@ struct mlxsw_sp_router {
         struct mlxsw_sp_lpm_tree lpm_trees[MLXSW_SP_LPM_TREE_COUNT];
         struct mlxsw_sp_vr vrs[MLXSW_SP_VIRTUAL_ROUTER_MAX];
         struct rhashtable neigh_ht;
+        struct {
+                struct delayed_work dw;
+                unsigned long interval; /* ms */
+        } neighs_update;
 };
 
 struct mlxsw_sp {
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 90d382a5d6a7..db1c2c42cd3b 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
  * Copyright (c) 2016 Jiri Pirko <jiri@mellanox.com>
  * Copyright (c) 2016 Ido Schimmel <idosch@mellanox.com>
+ * Copyright (c) 2016 Yotam Gigi <yotamg@mellanox.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -38,6 +39,8 @@
 #include <linux/rhashtable.h>
 #include <linux/bitops.h>
 #include <linux/in6.h>
+#include <linux/notifier.h>
+#include <net/netevent.h>
 #include <net/neighbour.h>
 #include <net/arp.h>
 
@@ -676,14 +679,199 @@ void mlxsw_sp_router_neigh_destroy(struct net_device *dev,
         mlxsw_sp_neigh_entry_destroy(neigh_entry);
 }
 
+static void
+mlxsw_sp_router_neighs_update_interval_init(struct mlxsw_sp *mlxsw_sp)
+{
+        unsigned long interval = NEIGH_VAR(&arp_tbl.parms, DELAY_PROBE_TIME);
+
+        mlxsw_sp->router.neighs_update.interval = jiffies_to_msecs(interval);
+}
+
+static void mlxsw_sp_router_neigh_ent_ipv4_process(struct mlxsw_sp *mlxsw_sp,
+                                                   char *rauhtd_pl,
+                                                   int ent_index)
+{
+        struct net_device *dev;
+        struct neighbour *n;
+        __be32 dipn;
+        u32 dip;
+        u16 rif;
+
+        mlxsw_reg_rauhtd_ent_ipv4_unpack(rauhtd_pl, ent_index, &rif, &dip);
+
+        if (!mlxsw_sp->rifs[rif]) {
+                dev_err_ratelimited(mlxsw_sp->bus_info->dev, "Incorrect RIF in neighbour entry\n");
+                return;
+        }
+
+        dipn = htonl(dip);
+        dev = mlxsw_sp->rifs[rif]->dev;
+        n = neigh_lookup(&arp_tbl, &dipn, dev);
+        if (!n) {
+                netdev_err(dev, "Failed to find matching neighbour for IP=%pI4h\n",
+                           &dip);
+                return;
+        }
+
+        netdev_dbg(dev, "Updating neighbour with IP=%pI4h\n", &dip);
+        neigh_event_send(n, NULL);
+        neigh_release(n);
+}
+
+static void mlxsw_sp_router_neigh_rec_ipv4_process(struct mlxsw_sp *mlxsw_sp,
+                                                   char *rauhtd_pl,
+                                                   int rec_index)
+{
+        u8 num_entries;
+        int i;
+
+        num_entries = mlxsw_reg_rauhtd_ipv4_rec_num_entries_get(rauhtd_pl,
+                                                                rec_index);
+        /* Hardware starts counting at 0, so add 1. */
+        num_entries++;
+
+        /* Each record consists of several neighbour entries. */
+        for (i = 0; i < num_entries; i++) {
+                int ent_index;
+
+                ent_index = rec_index * MLXSW_REG_RAUHTD_IPV4_ENT_PER_REC + i;
+                mlxsw_sp_router_neigh_ent_ipv4_process(mlxsw_sp, rauhtd_pl,
+                                                       ent_index);
+        }
+
+}
+
+static void mlxsw_sp_router_neigh_rec_process(struct mlxsw_sp *mlxsw_sp,
+                                              char *rauhtd_pl, int rec_index)
+{
+        switch (mlxsw_reg_rauhtd_rec_type_get(rauhtd_pl, rec_index)) {
+        case MLXSW_REG_RAUHTD_TYPE_IPV4:
+                mlxsw_sp_router_neigh_rec_ipv4_process(mlxsw_sp, rauhtd_pl,
+                                                       rec_index);
+                break;
+        case MLXSW_REG_RAUHTD_TYPE_IPV6:
+                WARN_ON_ONCE(1);
+                break;
+        }
+}
+
+static void
+mlxsw_sp_router_neighs_update_work_schedule(struct mlxsw_sp *mlxsw_sp)
+{
+        unsigned long interval = mlxsw_sp->router.neighs_update.interval;
+
+        mlxsw_core_schedule_dw(&mlxsw_sp->router.neighs_update.dw,
+                               msecs_to_jiffies(interval));
+}
+
+static void mlxsw_sp_router_neighs_update_work(struct work_struct *work)
+{
+        struct mlxsw_sp *mlxsw_sp;
+        char *rauhtd_pl;
+        u8 num_rec;
+        int i, err;
+
+        rauhtd_pl = kmalloc(MLXSW_REG_RAUHTD_LEN, GFP_KERNEL);
+        if (!rauhtd_pl)
+                return;
+
+        mlxsw_sp = container_of(work, struct mlxsw_sp,
+                                router.neighs_update.dw.work);
+
+        /* Make sure the neighbour's netdev isn't removed in the
+         * process.
+         */
+        rtnl_lock();
+        do {
+                mlxsw_reg_rauhtd_pack(rauhtd_pl, MLXSW_REG_RAUHTD_TYPE_IPV4);
+                err = mlxsw_reg_query(mlxsw_sp->core, MLXSW_REG(rauhtd),
+                                      rauhtd_pl);
+                if (err) {
+                        dev_err_ratelimited(mlxsw_sp->bus_info->dev, "Failed to dump neighbour talbe\n");
+                        break;
+                }
+                num_rec = mlxsw_reg_rauhtd_num_rec_get(rauhtd_pl);
+                for (i = 0; i < num_rec; i++)
+                        mlxsw_sp_router_neigh_rec_process(mlxsw_sp, rauhtd_pl,
+                                                          i);
+        } while (num_rec);
+        rtnl_unlock();
+
+        kfree(rauhtd_pl);
+        mlxsw_sp_router_neighs_update_work_schedule(mlxsw_sp);
+}
+
+static int mlxsw_sp_router_netevent_event(struct notifier_block *unused,
+                                          unsigned long event, void *ptr)
+{
+        struct mlxsw_sp_port *mlxsw_sp_port;
+        struct mlxsw_sp *mlxsw_sp;
+        unsigned long interval;
+        struct neigh_parms *p;
+
+        switch (event) {
+        case NETEVENT_DELAY_PROBE_TIME_UPDATE:
+                p = ptr;
+
+                /* We don't care about changes in the default table. */
+                if (!p->dev || p->tbl != &arp_tbl)
+                        return NOTIFY_DONE;
+
+                /* We are in atomic context and can't take RTNL mutex,
+                 * so use RCU variant to walk the device chain.
+                 */
+                mlxsw_sp_port = mlxsw_sp_port_lower_dev_hold(p->dev);
+                if (!mlxsw_sp_port)
+                        return NOTIFY_DONE;
+
+                mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+                interval = jiffies_to_msecs(NEIGH_VAR(p, DELAY_PROBE_TIME));
+                mlxsw_sp->router.neighs_update.interval = interval;
+
+                mlxsw_sp_port_dev_put(mlxsw_sp_port);
+                break;
+        }
+
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block mlxsw_sp_router_netevent_nb __read_mostly = {
+        .notifier_call = mlxsw_sp_router_netevent_event,
+};
+
 static int mlxsw_sp_neigh_init(struct mlxsw_sp *mlxsw_sp)
 {
-        return rhashtable_init(&mlxsw_sp->router.neigh_ht,
-                               &mlxsw_sp_neigh_ht_params);
+        int err;
+
+        err = rhashtable_init(&mlxsw_sp->router.neigh_ht,
+                              &mlxsw_sp_neigh_ht_params);
+        if (err)
+                return err;
+
+        /* Initialize the polling interval according to the default
+         * table.
+         */
+        mlxsw_sp_router_neighs_update_interval_init(mlxsw_sp);
+
+        err = register_netevent_notifier(&mlxsw_sp_router_netevent_nb);
+        if (err)
+                goto err_register_netevent_notifier;
+
+        INIT_DELAYED_WORK(&mlxsw_sp->router.neighs_update.dw,
+                          mlxsw_sp_router_neighs_update_work);
+        mlxsw_core_schedule_dw(&mlxsw_sp->router.neighs_update.dw, 0);
+
+        return 0;
+
+err_register_netevent_notifier:
+        rhashtable_destroy(&mlxsw_sp->router.neigh_ht);
+        return err;
 }
 
 static void mlxsw_sp_neigh_fini(struct mlxsw_sp *mlxsw_sp)
 {
+        cancel_delayed_work_sync(&mlxsw_sp->router.neighs_update.dw);
+        unregister_netevent_notifier(&mlxsw_sp_router_netevent_nb);
         rhashtable_destroy(&mlxsw_sp->router.neigh_ht);
 }