FreeBSD/Linux Kernel Cross Reference
sys/net/route/route_subscription.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2021-2022 Alexander V. Chernikov
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    #include "opt_route.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/malloc.h>
    #include <sys/socket.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/rmlock.h>
    
    #include <net/route.h>
    #include <net/route/route_ctl.h>
    #include <net/route/route_var.h>
    #include <net/route/nhop.h>
    
    struct rib_subscription {
            CK_STAILQ_ENTRY(rib_subscription)       next;
            rib_subscription_cb_t                   *func;
            void                                    *arg;
            struct rib_head                         *rnh;
            enum rib_subscription_type              type;
            struct epoch_context                    epoch_ctx;
    };
    
    static void destroy_subscription_epoch(epoch_context_t ctx);
    
    void
    rib_notify(struct rib_head *rnh, enum rib_subscription_type type,
        struct rib_cmd_info *rc)
    {
            struct rib_subscription *rs;
    
            CK_STAILQ_FOREACH(rs, &rnh->rnh_subscribers, next) {
                    if (rs->type == type)
                            rs->func(rnh, rc, rs->arg);
            }
    }
    
    static struct rib_subscription *
    allocate_subscription(rib_subscription_cb_t *f, void *arg,
        enum rib_subscription_type type, bool waitok)
    {
            struct rib_subscription *rs;
            int flags = M_ZERO | (waitok ? M_WAITOK : M_NOWAIT);
    
            rs = malloc(sizeof(struct rib_subscription), M_RTABLE, flags);
            if (rs == NULL)
                    return (NULL);
    
            rs->func = f;
            rs->arg = arg;
            rs->type = type;
    
            return (rs);
    }
    
    /*
     * Subscribe for the changes in the routing table specified by @fibnum and
     *  @family.
     *
     * Returns pointer to the subscription structure on success.
     */
    struct rib_subscription *
    rib_subscribe(uint32_t fibnum, int family, rib_subscription_cb_t *f, void *arg,
        enum rib_subscription_type type, bool waitok)
    {
            struct rib_head *rnh;
            struct epoch_tracker et;
    
            NET_EPOCH_ENTER(et);
           KASSERT((fibnum < rt_numfibs), ("%s: bad fibnum", __func__));
           rnh = rt_tables_get_rnh(fibnum, family);
           NET_EPOCH_EXIT(et);
   
           return (rib_subscribe_internal(rnh, f, arg, type, waitok));
   }
   
   struct rib_subscription *
   rib_subscribe_internal(struct rib_head *rnh, rib_subscription_cb_t *f, void *arg,
       enum rib_subscription_type type, bool waitok)
   {
           struct rib_subscription *rs;
           struct epoch_tracker et;
   
           if ((rs = allocate_subscription(f, arg, type, waitok)) == NULL)
                   return (NULL);
           rs->rnh = rnh;
   
           NET_EPOCH_ENTER(et);
           RIB_WLOCK(rnh);
           CK_STAILQ_INSERT_HEAD(&rnh->rnh_subscribers, rs, next);
           RIB_WUNLOCK(rnh);
           NET_EPOCH_EXIT(et);
   
           return (rs);
   }
   
   struct rib_subscription *
   rib_subscribe_locked(struct rib_head *rnh, rib_subscription_cb_t *f, void *arg,
       enum rib_subscription_type type)
   {
           struct rib_subscription *rs;
   
           NET_EPOCH_ASSERT();
           RIB_WLOCK_ASSERT(rnh);
   
           if ((rs = allocate_subscription(f, arg, type, false)) == NULL)
                   return (NULL);
           rs->rnh = rnh;
   
           CK_STAILQ_INSERT_HEAD(&rnh->rnh_subscribers, rs, next);
   
           return (rs);
   }
   
   /*
    * Remove rtable subscription @rs from the routing table.
    * Needs to be run in network epoch.
    */
   void
   rib_unsubscribe(struct rib_subscription *rs)
   {
           struct rib_head *rnh = rs->rnh;
   
           NET_EPOCH_ASSERT();
   
           RIB_WLOCK(rnh);
           CK_STAILQ_REMOVE(&rnh->rnh_subscribers, rs, rib_subscription, next);
           RIB_WUNLOCK(rnh);
   
           NET_EPOCH_CALL(destroy_subscription_epoch, &rs->epoch_ctx);
   }
   
   void
   rib_unsubscribe_locked(struct rib_subscription *rs)
   {
           struct rib_head *rnh = rs->rnh;
   
           NET_EPOCH_ASSERT();
           RIB_WLOCK_ASSERT(rnh);
   
           CK_STAILQ_REMOVE(&rnh->rnh_subscribers, rs, rib_subscription, next);
   
           NET_EPOCH_CALL(destroy_subscription_epoch, &rs->epoch_ctx);
   }
   
   /*
    * Epoch callback indicating subscription is safe to destroy
    */
   static void
   destroy_subscription_epoch(epoch_context_t ctx)
   {
           struct rib_subscription *rs;
   
           rs = __containerof(ctx, struct rib_subscription, epoch_ctx);
   
           free(rs, M_RTABLE);
   }
   
   void
   rib_init_subscriptions(struct rib_head *rnh)
   {
   
           CK_STAILQ_INIT(&rnh->rnh_subscribers);
   }
   
   void
   rib_destroy_subscriptions(struct rib_head *rnh)
   {
           struct rib_subscription *rs;
           struct epoch_tracker et;
   
           NET_EPOCH_ENTER(et);
           RIB_WLOCK(rnh);
           while ((rs = CK_STAILQ_FIRST(&rnh->rnh_subscribers)) != NULL) {
                   CK_STAILQ_REMOVE_HEAD(&rnh->rnh_subscribers, next);
                   NET_EPOCH_CALL(destroy_subscription_epoch, &rs->epoch_ctx);
           }
           RIB_WUNLOCK(rnh);
           NET_EPOCH_EXIT(et);
   }

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