zebra: limit queued route updates

[mirror_frr.git] / zebra / zebra_dplane.c

/*
 * Zebra dataplane layer.
 * Copyright (c) 2018 Volta Networks, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "lib/libfrr.h"
#include "lib/debug.h"
#include "lib/frratomic.h"
#include "lib/frr_pthread.h"
#include "lib/memory.h"
#include "lib/queue.h"
#include "lib/zebra.h"
#include "zebra/zebra_memory.h"
#include "zebra/zserv.h"
#include "zebra/zebra_dplane.h"
#include "zebra/rt.h"
#include "zebra/debug.h"

/* Memory type for context blocks */
DEFINE_MTYPE(ZEBRA, DP_CTX, "Zebra DPlane Ctx")
DEFINE_MTYPE(ZEBRA, DP_PROV, "Zebra DPlane Provider")

#ifndef AOK
#  define AOK 0
#endif

/* Default value for max queued incoming updates */
const uint32_t DPLANE_DEFAULT_MAX_QUEUED = 200;


/* Validation check macro for context blocks */
/* #define DPLANE_DEBUG 1 */

#ifdef DPLANE_DEBUG

#  define DPLANE_CTX_VALID(p)   \
                assert((p) != NULL)

#else

#  define DPLANE_CTX_VALID(p)

#endif  /* DPLANE_DEBUG */

/*
 * The context block used to exchange info about route updates across
 * the boundary between the zebra main context (and pthread) and the
 * dataplane layer (and pthread).
 */
struct zebra_dplane_ctx {

        /* Operation code */
        enum dplane_op_e zd_op;

        /* Status on return */
        enum zebra_dplane_result zd_status;

        /* TODO -- internal/sub-operation status? */
        enum zebra_dplane_status zd_remote_status;
        enum zebra_dplane_status zd_kernel_status;

        /* Dest and (optional) source prefixes */
        struct prefix zd_dest;
        struct prefix zd_src;

        bool zd_is_update;

        uint32_t zd_seq;
        uint32_t zd_old_seq;
        vrf_id_t zd_vrf_id;
        uint32_t zd_table_id;

        int zd_type;
        int zd_old_type;

        afi_t zd_afi;
        safi_t zd_safi;

        route_tag_t zd_tag;
        route_tag_t zd_old_tag;
        uint32_t zd_metric;
        uint32_t zd_old_metric;
        uint16_t zd_instance;
        uint16_t zd_old_instance;

        uint8_t zd_distance;
        uint8_t zd_old_distance;

        uint32_t zd_mtu;
        uint32_t zd_nexthop_mtu;

        /* Namespace info */
        struct zebra_dplane_info zd_ns_info;

        /* Nexthops */
        struct nexthop_group zd_ng;

        /* "Previous" nexthops, used only in route updates without netlink */
        struct nexthop_group zd_old_ng;

        /* TODO -- use fixed array of nexthops, to avoid mallocs? */

        /* Embedded list linkage */
        TAILQ_ENTRY(zebra_dplane_ctx) zd_q_entries;
};

/*
 * Registration block for one dataplane provider.
 */
struct zebra_dplane_provider {
        /* Name */
        char dp_name[DPLANE_PROVIDER_NAMELEN + 1];

        /* Priority, for ordering among providers */
        uint8_t dp_priority;

        /* Id value */
        uint32_t dp_id;

        dplane_provider_process_fp dp_fp;

        dplane_provider_fini_fp dp_fini;

        _Atomic uint64_t dp_in_counter;
        _Atomic uint64_t dp_error_counter;

        /* Embedded list linkage */
        TAILQ_ENTRY(zebra_dplane_provider) dp_q_providers;

};

/*
 * Globals
 */
static struct zebra_dplane_globals {
        /* Mutex to control access to dataplane components */
        pthread_mutex_t dg_mutex;

        /* Results callback registered by zebra 'core' */
        dplane_results_fp dg_results_cb;

        /* Sentinel for beginning of shutdown */
        volatile bool dg_is_shutdown;

        /* Sentinel for end of shutdown */
        volatile bool dg_run;

        /* Route-update context queue inbound to the dataplane */
        TAILQ_HEAD(zdg_ctx_q, zebra_dplane_ctx) dg_route_ctx_q;

        /* Ordered list of providers */
        TAILQ_HEAD(zdg_prov_q, zebra_dplane_provider) dg_providers_q;

        /* Counter used to assign internal ids to providers */
        uint32_t dg_provider_id;

        /* Limit number of pending, unprocessed updates */
        _Atomic uint32_t dg_max_queued_updates;

        _Atomic uint64_t dg_routes_in;
        _Atomic uint32_t dg_routes_queued;
        _Atomic uint32_t dg_routes_queued_max;
        _Atomic uint64_t dg_route_errors;

        /* Event-delivery context 'master' for the dplane */
        struct thread_master *dg_master;

        /* Event/'thread' pointer for queued updates */
        struct thread *dg_t_update;

        /* Event pointer for pending shutdown check loop */
        struct thread *dg_t_shutdown_check;

} zdplane_info;

/*
 * Lock and unlock for interactions with the zebra 'core'
 */
#define DPLANE_LOCK() pthread_mutex_lock(&zdplane_info.dg_mutex)

#define DPLANE_UNLOCK() pthread_mutex_unlock(&zdplane_info.dg_mutex)

/* Prototypes */
static int dplane_route_process(struct thread *event);

/*
 * Public APIs
 */

/*
 * Allocate a dataplane update context
 */
static struct zebra_dplane_ctx *dplane_ctx_alloc(void)
{
        struct zebra_dplane_ctx *p;

        /* TODO -- just alloc'ing memory, but would like to maintain
         * a pool
         */
        p = XCALLOC(MTYPE_DP_CTX, sizeof(struct zebra_dplane_ctx));

        return p;
}

/*
 * Free a dataplane results context.
 */
static void dplane_ctx_free(struct zebra_dplane_ctx **pctx)
{
        if (pctx) {
                DPLANE_CTX_VALID(*pctx);

                /* TODO -- just freeing memory, but would like to maintain
                 * a pool
                 */

                /* Free embedded nexthops */
                if ((*pctx)->zd_ng.nexthop) {
                        /* This deals with recursive nexthops too */
                        nexthops_free((*pctx)->zd_ng.nexthop);
                }

                if ((*pctx)->zd_old_ng.nexthop) {
                        /* This deals with recursive nexthops too */
                        nexthops_free((*pctx)->zd_old_ng.nexthop);
                }

                XFREE(MTYPE_DP_CTX, *pctx);
                *pctx = NULL;
        }
}

/*
 * Return a context block to the dplane module after processing
 */
void dplane_ctx_fini(struct zebra_dplane_ctx **pctx)
{
        /* TODO -- enqueue for next provider; for now, just free */
        dplane_ctx_free(pctx);
}

/* Enqueue a context block */
void dplane_ctx_enqueue_tail(struct dplane_ctx_q *q,
                             const struct zebra_dplane_ctx *ctx)
{
        TAILQ_INSERT_TAIL(q, (struct zebra_dplane_ctx *)ctx, zd_q_entries);
}

/* Dequeue a context block from the head of a list */
void dplane_ctx_dequeue(struct dplane_ctx_q *q, struct zebra_dplane_ctx **ctxp)
{
        struct zebra_dplane_ctx *ctx = TAILQ_FIRST(q);

        if (ctx)
                TAILQ_REMOVE(q, ctx, zd_q_entries);

        *ctxp = ctx;
}

/*
 * Accessors for information from the context object
 */
enum zebra_dplane_result dplane_ctx_get_status(
        const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_status;
}

enum dplane_op_e dplane_ctx_get_op(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_op;
}

const char *dplane_op2str(enum dplane_op_e op)
{
        const char *ret = "UNKNOWN";

        switch (op) {
        case DPLANE_OP_NONE:
                ret = "NONE";
                break;

        /* Route update */
        case DPLANE_OP_ROUTE_INSTALL:
                ret = "ROUTE_INSTALL";
                break;
        case DPLANE_OP_ROUTE_UPDATE:
                ret = "ROUTE_UPDATE";
                break;
        case DPLANE_OP_ROUTE_DELETE:
                ret = "ROUTE_DELETE";
                break;

        };

        return ret;
}

const char *dplane_res2str(enum zebra_dplane_result res)
{
        const char *ret = "<Unknown>";

        switch (res) {
        case ZEBRA_DPLANE_REQUEST_FAILURE:
                ret = "FAILURE";
                break;
        case ZEBRA_DPLANE_REQUEST_QUEUED:
                ret = "QUEUED";
                break;
        case ZEBRA_DPLANE_REQUEST_SUCCESS:
                ret = "SUCCESS";
                break;
        };

        return ret;
}

const struct prefix *dplane_ctx_get_dest(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return &(ctx->zd_dest);
}

/* Source prefix is a little special - return NULL for "no src prefix" */
const struct prefix *dplane_ctx_get_src(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        if (ctx->zd_src.prefixlen == 0 &&
            IN6_IS_ADDR_UNSPECIFIED(&(ctx->zd_src.u.prefix6))) {
                return NULL;
        } else {
                return &(ctx->zd_src);
        }
}

bool dplane_ctx_is_update(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_is_update;
}

uint32_t dplane_ctx_get_seq(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_seq;
}

uint32_t dplane_ctx_get_old_seq(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_old_seq;
}

vrf_id_t dplane_ctx_get_vrf(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_vrf_id;
}

int dplane_ctx_get_type(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_type;
}

int dplane_ctx_get_old_type(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_old_type;
}

afi_t dplane_ctx_get_afi(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_afi;
}

safi_t dplane_ctx_get_safi(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_safi;
}

uint32_t dplane_ctx_get_table(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_table_id;
}

route_tag_t dplane_ctx_get_tag(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_tag;
}

route_tag_t dplane_ctx_get_old_tag(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_old_tag;
}

uint16_t dplane_ctx_get_instance(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_instance;
}

uint16_t dplane_ctx_get_old_instance(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_instance;
}

uint32_t dplane_ctx_get_metric(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_metric;
}

uint32_t dplane_ctx_get_old_metric(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_old_metric;
}

uint32_t dplane_ctx_get_mtu(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_mtu;
}

uint32_t dplane_ctx_get_nh_mtu(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_nexthop_mtu;
}

uint8_t dplane_ctx_get_distance(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_distance;
}

uint8_t dplane_ctx_get_old_distance(const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return ctx->zd_old_distance;
}

const struct nexthop_group *dplane_ctx_get_ng(
        const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return &(ctx->zd_ng);
}

const struct nexthop_group *dplane_ctx_get_old_ng(
        const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return &(ctx->zd_old_ng);
}

const struct zebra_dplane_info *dplane_ctx_get_ns(
        const struct zebra_dplane_ctx *ctx)
{
        DPLANE_CTX_VALID(ctx);

        return &(ctx->zd_ns_info);
}

/*
 * End of dplane context accessors
 */

/*
 * Retrieve the limit on the number of pending, unprocessed updates.
 */
uint32_t dplane_get_in_queue_limit(void)
{
        return atomic_load_explicit(&zdplane_info.dg_max_queued_updates,
                                    memory_order_relaxed);
}

/*
 * Configure limit on the number of pending, queued updates.
 */
void dplane_set_in_queue_limit(uint32_t limit, bool set)
{
        /* Reset to default on 'unset' */
        if (!set)
                limit = DPLANE_DEFAULT_MAX_QUEUED;

        atomic_store_explicit(&zdplane_info.dg_max_queued_updates, limit,
                              memory_order_relaxed);
}

/*
 * Retrieve the current queue depth of incoming, unprocessed updates
 */
uint32_t dplane_get_in_queue_len(void)
{
        return atomic_load_explicit(&zdplane_info.dg_routes_queued,
                                    memory_order_seq_cst);
}

/*
 * Initialize a context block for a route update from zebra data structs.
 */
static int dplane_ctx_route_init(struct zebra_dplane_ctx *ctx,
                                 enum dplane_op_e op,
                                 struct route_node *rn,
                                 struct route_entry *re)
{
        int ret = EINVAL;
        const struct route_table *table = NULL;
        const rib_table_info_t *info;
        const struct prefix *p, *src_p;
        struct zebra_ns *zns;
        struct zebra_vrf *zvrf;
        struct nexthop *nexthop;

        if (!ctx || !rn || !re)
                goto done;

        ctx->zd_op = op;

        ctx->zd_type = re->type;
        ctx->zd_old_type = re->type;

        /* Prefixes: dest, and optional source */
        srcdest_rnode_prefixes(rn, &p, &src_p);

        prefix_copy(&(ctx->zd_dest), p);

        if (src_p)
                prefix_copy(&(ctx->zd_src), src_p);
        else
                memset(&(ctx->zd_src), 0, sizeof(ctx->zd_src));

        ctx->zd_table_id = re->table;

        ctx->zd_metric = re->metric;
        ctx->zd_old_metric = re->metric;
        ctx->zd_vrf_id = re->vrf_id;
        ctx->zd_mtu = re->mtu;
        ctx->zd_nexthop_mtu = re->nexthop_mtu;
        ctx->zd_instance = re->instance;
        ctx->zd_tag = re->tag;
        ctx->zd_old_tag = re->tag;
        ctx->zd_distance = re->distance;

        table = srcdest_rnode_table(rn);
        info = table->info;

        ctx->zd_afi = info->afi;
        ctx->zd_safi = info->safi;

        /* Extract ns info - can't use pointers to 'core' structs */
        zvrf = vrf_info_lookup(re->vrf_id);
        zns = zvrf->zns;

        zebra_dplane_info_from_zns(&(ctx->zd_ns_info), zns, true /*is_cmd*/);

#if defined(HAVE_NETLINK)
        /* Increment message counter after copying to context struct - may need
         * two messages in some 'update' cases.
         */
        if (op == DPLANE_OP_ROUTE_UPDATE)
                zns->netlink_cmd.seq += 2;
        else
                zns->netlink_cmd.seq++;
#endif /* NETLINK*/

        /* Copy nexthops; recursive info is included too */
        copy_nexthops(&(ctx->zd_ng.nexthop), re->ng.nexthop, NULL);

        /* TODO -- maybe use array of nexthops to avoid allocs? */

        /* Ensure that the dplane's nexthop flag is clear. */
        for (ALL_NEXTHOPS(ctx->zd_ng, nexthop))
                UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_FIB);

        /* Trying out the sequence number idea, so we can try to detect
         * when a result is stale.
         */
        re->dplane_sequence++;
        ctx->zd_seq = re->dplane_sequence;

        ret = AOK;

done:
        return ret;
}

/*
 * Enqueue a new route update,
 * and ensure an event is active for the dataplane thread.
 */
static int dplane_route_enqueue(struct zebra_dplane_ctx *ctx)
{
        int ret = EINVAL;
        uint32_t high, curr;

        /* Enqueue for processing by the dataplane thread */
        DPLANE_LOCK();
        {
                TAILQ_INSERT_TAIL(&zdplane_info.dg_route_ctx_q, ctx,
                                  zd_q_entries);
        }
        DPLANE_UNLOCK();

        curr = atomic_add_fetch_explicit(&zdplane_info.dg_routes_queued,
                                         1, memory_order_seq_cst);

        /* Maybe update high-water counter also */
        high = atomic_load_explicit(&zdplane_info.dg_routes_queued_max,
                                    memory_order_seq_cst);
        while (high < curr) {
                if (atomic_compare_exchange_weak_explicit(
                            &zdplane_info.dg_routes_queued_max,
                            &high, curr,
                            memory_order_seq_cst,
                            memory_order_seq_cst))
                        break;
        }

        /* Ensure that an event for the dataplane thread is active */
        thread_add_event(zdplane_info.dg_master, dplane_route_process, NULL, 0,
                         &zdplane_info.dg_t_update);

        ret = AOK;

        return ret;
}

/*
 * Attempt to dequeue a route-update block
 */
static struct zebra_dplane_ctx *dplane_route_dequeue(void)
{
        struct zebra_dplane_ctx *ctx = NULL;

        DPLANE_LOCK();
        {
                ctx = TAILQ_FIRST(&zdplane_info.dg_route_ctx_q);
                if (ctx) {
                        TAILQ_REMOVE(&zdplane_info.dg_route_ctx_q,
                                     ctx, zd_q_entries);
                }
        }
        DPLANE_UNLOCK();

        return ctx;
}

/*
 * Utility that prepares a route update and enqueues it for processing
 */
static enum zebra_dplane_result
dplane_route_update_internal(struct route_node *rn,
                             struct route_entry *re,
                             struct route_entry *old_re,
                             enum dplane_op_e op)
{
        enum zebra_dplane_result result = ZEBRA_DPLANE_REQUEST_FAILURE;
        int ret = EINVAL;
        struct zebra_dplane_ctx *ctx = NULL;

        /* Obtain context block */
        ctx = dplane_ctx_alloc();
        if (ctx == NULL) {
                ret = ENOMEM;
                goto done;
        }

        /* Init context with info from zebra data structs */
        ret = dplane_ctx_route_init(ctx, op, rn, re);
        if (ret == AOK) {
                /* Capture some extra info for update case
                 * where there's a different 'old' route.
                 */
                if ((op == DPLANE_OP_ROUTE_UPDATE) &&
                    old_re && (old_re != re)) {
                        ctx->zd_is_update = true;

                        old_re->dplane_sequence++;
                        ctx->zd_old_seq = old_re->dplane_sequence;

                        ctx->zd_old_tag = old_re->tag;
                        ctx->zd_old_type = old_re->type;
                        ctx->zd_old_instance = old_re->instance;
                        ctx->zd_old_distance = old_re->distance;
                        ctx->zd_old_metric = old_re->metric;

#ifndef HAVE_NETLINK
                        /* For bsd, capture previous re's nexthops too, sigh.
                         * We'll need these to do per-nexthop deletes.
                         */
                        copy_nexthops(&(ctx->zd_old_ng.nexthop),
                                      old_re->ng.nexthop, NULL);
#endif  /* !HAVE_NETLINK */
                }

                /* Enqueue context for processing */
                ret = dplane_route_enqueue(ctx);
        }

done:
        /* Update counter */
        atomic_fetch_add_explicit(&zdplane_info.dg_routes_in, 1,
                                  memory_order_relaxed);

        if (ret == AOK)
                result = ZEBRA_DPLANE_REQUEST_QUEUED;
        else if (ctx) {
                atomic_fetch_add_explicit(&zdplane_info.dg_route_errors, 1,
                                          memory_order_relaxed);
                dplane_ctx_free(&ctx);
        }

        return result;
}

/*
 * Enqueue a route 'add' for the dataplane.
 */
enum zebra_dplane_result dplane_route_add(struct route_node *rn,
                                          struct route_entry *re)
{
        enum zebra_dplane_result ret = ZEBRA_DPLANE_REQUEST_FAILURE;

        if (rn == NULL || re == NULL)
                goto done;

        ret = dplane_route_update_internal(rn, re, NULL,
                                           DPLANE_OP_ROUTE_INSTALL);

done:
        return ret;
}

/*
 * Enqueue a route update for the dataplane.
 */
enum zebra_dplane_result dplane_route_update(struct route_node *rn,
                                             struct route_entry *re,
                                             struct route_entry *old_re)
{
        enum zebra_dplane_result ret = ZEBRA_DPLANE_REQUEST_FAILURE;

        if (rn == NULL || re == NULL)
                goto done;

        ret = dplane_route_update_internal(rn, re, old_re,
                                           DPLANE_OP_ROUTE_UPDATE);
done:
        return ret;
}

/*
 * Enqueue a route removal for the dataplane.
 */
enum zebra_dplane_result dplane_route_delete(struct route_node *rn,
                                             struct route_entry *re)
{
        enum zebra_dplane_result ret = ZEBRA_DPLANE_REQUEST_FAILURE;

        if (rn == NULL || re == NULL)
                goto done;

        ret = dplane_route_update_internal(rn, re, NULL,
                                           DPLANE_OP_ROUTE_DELETE);

done:
        return ret;
}

/*
 * Event handler function for routing updates
 */
static int dplane_route_process(struct thread *event)
{
        enum zebra_dplane_result res;
        struct zebra_dplane_ctx *ctx;

        while (1) {
                /* Check for shutdown */
                if (!zdplane_info.dg_run)
                        break;

                /* TODO -- limit number of updates per cycle? */
                ctx = dplane_route_dequeue();
                if (ctx == NULL)
                        break;

                /* Update counter */
                atomic_fetch_sub_explicit(&zdplane_info.dg_routes_queued, 1,
                                          memory_order_relaxed);

                if (IS_ZEBRA_DEBUG_DPLANE_DETAIL) {
                        char dest_str[PREFIX_STRLEN];

                        prefix2str(dplane_ctx_get_dest(ctx),
                                   dest_str, sizeof(dest_str));

                        zlog_debug("%u:%s Dplane route update ctx %p op %s",
                                   dplane_ctx_get_vrf(ctx), dest_str,
                                   ctx, dplane_op2str(dplane_ctx_get_op(ctx)));
                }

                /* TODO -- support series of providers */

                /* Initially, just doing kernel-facing update here */
                res = kernel_route_update(ctx);

                if (res != ZEBRA_DPLANE_REQUEST_SUCCESS)
                        atomic_fetch_add_explicit(&zdplane_info.dg_route_errors,
                                                  1, memory_order_relaxed);

                ctx->zd_status = res;

                /* Enqueue result to zebra main context */
                zdplane_info.dg_results_cb(ctx);

                ctx = NULL;
        }

        return 0;
}

/*
 * Handler for 'show dplane'
 */
int dplane_show_helper(struct vty *vty, bool detailed)
{
        uint64_t queued, limit, queue_max, errs, incoming;

        /* Using atomics because counters are being changed in different
         * contexts.
         */
        incoming = atomic_load_explicit(&zdplane_info.dg_routes_in,
                                        memory_order_relaxed);
        limit = atomic_load_explicit(&zdplane_info.dg_max_queued_updates,
                                     memory_order_relaxed);
        queued = atomic_load_explicit(&zdplane_info.dg_routes_queued,
                                      memory_order_relaxed);
        queue_max = atomic_load_explicit(&zdplane_info.dg_routes_queued_max,
                                         memory_order_relaxed);
        errs = atomic_load_explicit(&zdplane_info.dg_route_errors,
                                    memory_order_relaxed);

        vty_out(vty, "Route updates:            %"PRIu64"\n", incoming);
        vty_out(vty, "Route update errors:      %"PRIu64"\n", errs);
        vty_out(vty, "Route update queue limit: %"PRIu64"\n", limit);
        vty_out(vty, "Route update queue depth: %"PRIu64"\n", queued);
        vty_out(vty, "Route update queue max:   %"PRIu64"\n", queue_max);

        return CMD_SUCCESS;
}

/*
 * Handler for 'show dplane providers'
 */
int dplane_show_provs_helper(struct vty *vty, bool detailed)
{
        vty_out(vty, "Zebra dataplane providers:%s\n",
                (detailed ? " (detailed)" : ""));

        return CMD_SUCCESS;
}

/*
 * Provider registration
 */
int dplane_provider_register(const char *name,
                             enum dplane_provider_prio_e prio,
                             dplane_provider_process_fp fp,
                             dplane_provider_fini_fp fini_fp)
{
        int ret = 0;
        struct zebra_dplane_provider *p, *last;

        /* Validate */
        if (fp == NULL) {
                ret = EINVAL;
                goto done;
        }

        if (prio <= DPLANE_PRIO_NONE ||
            prio > DPLANE_PRIO_LAST) {
                ret = EINVAL;
                goto done;
        }

        /* Allocate and init new provider struct */
        p = XCALLOC(MTYPE_DP_PROV, sizeof(struct zebra_dplane_provider));
        if (p == NULL) {
                ret = ENOMEM;
                goto done;
        }

        strncpy(p->dp_name, name, DPLANE_PROVIDER_NAMELEN);
        p->dp_name[DPLANE_PROVIDER_NAMELEN] = '\0'; /* Belt-and-suspenders */

        p->dp_priority = prio;
        p->dp_fp = fp;
        p->dp_fini = fini_fp;

        /* Lock the lock - the dplane pthread may be running */
        DPLANE_LOCK();

        p->dp_id = ++zdplane_info.dg_provider_id;

        /* Insert into list ordered by priority */
        TAILQ_FOREACH(last, &zdplane_info.dg_providers_q, dp_q_providers) {
                if (last->dp_priority > p->dp_priority)
                        break;
        }

        if (last)
                TAILQ_INSERT_BEFORE(last, p, dp_q_providers);
        else
                TAILQ_INSERT_TAIL(&zdplane_info.dg_providers_q, p,
                                  dp_q_providers);

        /* And unlock */
        DPLANE_UNLOCK();

done:
        return ret;
}

/*
 * Zebra registers a results callback with the dataplane system
 */
int dplane_results_register(dplane_results_fp fp)
{
        zdplane_info.dg_results_cb = fp;
        return AOK;
}

/*
 * Initialize the dataplane module during startup, internal/private version
 */
static void zebra_dplane_init_internal(struct zebra_t *zebra)
{
        memset(&zdplane_info, 0, sizeof(zdplane_info));

        pthread_mutex_init(&zdplane_info.dg_mutex, NULL);

        TAILQ_INIT(&zdplane_info.dg_route_ctx_q);
        TAILQ_INIT(&zdplane_info.dg_providers_q);

        zdplane_info.dg_max_queued_updates = DPLANE_DEFAULT_MAX_QUEUED;

        /* TODO -- register default kernel 'provider' during init */

        zdplane_info.dg_run = true;

        /* TODO -- start dataplane pthread. We're using the zebra
         * core/main thread temporarily
         */
        zdplane_info.dg_master = zebra->master;
}

/* Indicates zebra shutdown/exit is in progress. Some operations may be
 * simplified or skipped during shutdown processing.
 */
bool dplane_is_in_shutdown(void)
{
        return zdplane_info.dg_is_shutdown;
}

/*
 * Early or pre-shutdown, de-init notification api. This runs pretty
 * early during zebra shutdown, as a signal to stop new work and prepare
 * for updates generated by shutdown/cleanup activity, as zebra tries to
 * remove everything it's responsible for.
 * NB: This runs in the main zebra thread context.
 */
void zebra_dplane_pre_finish(void)
{
        if (IS_ZEBRA_DEBUG_DPLANE)
                zlog_debug("Zebra dataplane pre-fini called");

        zdplane_info.dg_is_shutdown = true;

        /* Notify provider(s) of pending shutdown */
}

/*
 * Utility to determine whether work remains enqueued within the dplane;
 * used during system shutdown processing.
 */
static bool dplane_work_pending(void)
{
        struct zebra_dplane_ctx *ctx;

        /* TODO -- just checking incoming/pending work for now */
        DPLANE_LOCK();
        {
                ctx = TAILQ_FIRST(&zdplane_info.dg_route_ctx_q);
        }
        DPLANE_UNLOCK();

        return (ctx != NULL);
}

/*
 * Shutdown-time intermediate callback, used to determine when all pending
 * in-flight updates are done. If there's still work to do, reschedules itself.
 * If all work is done, schedules an event to the main zebra thread for
 * final zebra shutdown.
 * This runs in the dplane pthread context.
 */
static int dplane_check_shutdown_status(struct thread *event)
{
        if (IS_ZEBRA_DEBUG_DPLANE)
                zlog_debug("Zebra dataplane shutdown status check called");

        if (dplane_work_pending()) {
                /* Reschedule dplane check on a short timer */
                thread_add_timer_msec(zdplane_info.dg_master,
                                      dplane_check_shutdown_status,
                                      NULL, 100,
                                      &zdplane_info.dg_t_shutdown_check);

                /* TODO - give up and stop waiting after a short time? */

        } else {
                /* We appear to be done - schedule a final callback event
                 * for the zebra main pthread.
                 */
                thread_add_event(zebrad.master, zebra_finalize, NULL, 0, NULL);
        }

        return 0;
}

/*
 * Shutdown, de-init api. This runs pretty late during shutdown,
 * after zebra has tried to free/remove/uninstall all routes during shutdown.
 * At this point, dplane work may still remain to be done, so we can't just
 * blindly terminate. If there's still work to do, we'll periodically check
 * and when done, we'll enqueue a task to the zebra main thread for final
 * termination processing.
 *
 * NB: This runs in the main zebra thread context.
 */
void zebra_dplane_finish(void)
{
        if (IS_ZEBRA_DEBUG_DPLANE)
                zlog_debug("Zebra dataplane fini called");

        thread_add_event(zdplane_info.dg_master,
                         dplane_check_shutdown_status, NULL, 0,
                         &zdplane_info.dg_t_shutdown_check);
}

/*
 * Final phase of shutdown, after all work enqueued to dplane has been
 * processed. This is called from the zebra main pthread context.
 */
void zebra_dplane_shutdown(void)
{
        if (IS_ZEBRA_DEBUG_DPLANE)
                zlog_debug("Zebra dataplane shutdown called");

        /* Stop dplane thread, if it's running */

        zdplane_info.dg_run = false;

        THREAD_OFF(zdplane_info.dg_t_update);

        /* TODO */
        /* frr_pthread_stop(...) */

        /* Notify provider(s) of final shutdown */

        /* Clean-up provider objects */

        /* Clean queue(s) */
}

/*
 * Initialize the dataplane module at startup; called by zebra rib_init()
 */
void zebra_dplane_init(void)
{
        zebra_dplane_init_internal(&zebrad);
}