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

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2020 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.
     *
     * $FreeBSD$
     */
    
    #include "opt_inet.h"
    #include "opt_route.h"
    
    #include <sys/cdefs.h>
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/lock.h>
    #include <sys/rmlock.h>
    #include <sys/rwlock.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/refcount.h>
    #include <sys/socket.h>
    #include <sys/sysctl.h>
    #include <sys/kernel.h>
    
    #include <net/if.h>
    #include <net/if_var.h>
    #include <net/if_dl.h>
    #include <net/route.h>
    #include <net/route/route_ctl.h>
    #include <net/route/route_var.h>
    #include <net/vnet.h>
    
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    #include <netinet/in_fib.h>
    
    #include <net/route/nhop_utils.h>
    #include <net/route/nhop.h>
    #include <net/route/nhop_var.h>
    #include <net/route/nhgrp_var.h>
    
    #define DEBUG_MOD_NAME  nhgrp
    #define DEBUG_MAX_LEVEL LOG_DEBUG
    #include <net/route/route_debug.h>
    _DECLARE_DEBUG(LOG_INFO);
    
    /*
     * This file contains data structures management logic for the nexthop
     * groups ("nhgrp") route subsystem.
     *
     * Nexthop groups are used to store multiple routes available for the specific
     *  prefix. Nexthop groups are immutable and can be shared across multiple
     *  prefixes.
     *
     * Each group consists of a control plane part and a dataplane part.
     * Control plane is basically a collection of nexthop objects with
     *  weights and refcount.
     *
     * Datapath consists of a array of nexthop pointers, compiled from control
     *  plane data to support O(1) nexthop selection.
     *
     * For example, consider the following group:
     *  [(nh1, weight=100), (nh2, weight=200)]
     * It will compile to the following array:
     *  [nh1, nh2, nh2]
     *
     */
    
    static void consider_resize(struct nh_control *ctl, uint32_t new_gr_buckets,
        uint32_t new_idx_items);
    
    static int cmp_nhgrp(const struct nhgrp_priv *a, const struct nhgrp_priv *b);
    static unsigned int hash_nhgrp(const struct nhgrp_priv *obj);
    
    static unsigned
    djb_hash(const unsigned char *h, const int len)
    {
            unsigned int result = 0;
           int i;
   
           for (i = 0; i < len; i++)
                   result = 33 * result ^ h[i];
   
           return (result);
   }
   
   static int
   cmp_nhgrp(const struct nhgrp_priv *a, const struct nhgrp_priv *b)
   {
   
           /*
            * In case of consistent hashing, there can be multiple nexthop groups
            * with the same "control plane" list of nexthops with weights and a
            * different set of "data plane" nexthops.
            * For now, ignore the data plane and focus on the control plane list.
            */
           if (a->nhg_nh_count != b->nhg_nh_count || a->nhg_uidx != b->nhg_uidx)
                   return (0);
           return !memcmp(a->nhg_nh_weights, b->nhg_nh_weights,
               sizeof(struct weightened_nhop) * a->nhg_nh_count);
   }
   
   /*
    * Hash callback: calculate hash of an object
    */
   static unsigned int
   hash_nhgrp(const struct nhgrp_priv *obj)
   {
           const unsigned char *key;
   
           key = (const unsigned char *)obj->nhg_nh_weights;
   
           return (djb_hash(key, sizeof(struct weightened_nhop) * obj->nhg_nh_count));
   }
   
   /*
    * Returns object referenced and unlocked
    */
   struct nhgrp_priv *
   find_nhgrp(struct nh_control *ctl, const struct nhgrp_priv *key)
   {
           struct nhgrp_priv *priv_ret;
   
           NHOPS_RLOCK(ctl);
           CHT_SLIST_FIND_BYOBJ(&ctl->gr_head, mpath, key, priv_ret);
           if (priv_ret != NULL) {
                   if (refcount_acquire_if_not_zero(&priv_ret->nhg_refcount) == 0) {
                           /* refcount is 0 -> group is being deleted */
                           priv_ret = NULL;
                   }
           }
           NHOPS_RUNLOCK(ctl);
   
           return (priv_ret);
   }
   
   int
   link_nhgrp(struct nh_control *ctl, struct nhgrp_priv *grp_priv)
   {
           uint16_t idx;
           uint32_t new_num_buckets, new_num_items;
   
           NHOPS_WLOCK(ctl);
           /* Check if we need to resize hash and index */
           new_num_buckets = CHT_SLIST_GET_RESIZE_BUCKETS(&ctl->gr_head);
           new_num_items = bitmask_get_resize_items(&ctl->nh_idx_head);
   
           if (bitmask_alloc_idx(&ctl->nh_idx_head, &idx) != 0) {
                   NHOPS_WUNLOCK(ctl);
                   FIB_RH_LOG(LOG_DEBUG, ctl->ctl_rh, "Unable to allocate nhg index");
                   consider_resize(ctl, new_num_buckets, new_num_items);
                   return (0);
           }
   
           grp_priv->nhg_idx = idx;
           grp_priv->nh_control = ctl;
           CHT_SLIST_INSERT_HEAD(&ctl->gr_head, mpath, grp_priv);
   
           NHOPS_WUNLOCK(ctl);
   
           IF_DEBUG_LEVEL(LOG_DEBUG2) {
                   char nhgrp_buf[NHOP_PRINT_BUFSIZE] __unused;
                   FIB_RH_LOG(LOG_DEBUG2, ctl->ctl_rh, "linked %s",
                       nhgrp_print_buf(grp_priv->nhg, nhgrp_buf, sizeof(nhgrp_buf)));
           }
           consider_resize(ctl, new_num_buckets, new_num_items);
   
           return (1);
   }
   
   struct nhgrp_priv *
   unlink_nhgrp(struct nh_control *ctl, struct nhgrp_priv *key)
   {
           struct nhgrp_priv *nhg_priv_ret;
           int idx;
   
           NHOPS_WLOCK(ctl);
   
           CHT_SLIST_REMOVE(&ctl->gr_head, mpath, key, nhg_priv_ret);
   
           if (nhg_priv_ret == NULL) {
                   FIB_RH_LOG(LOG_DEBUG, ctl->ctl_rh, "Unable to find nhg");
                   NHOPS_WUNLOCK(ctl);
                   return (NULL);
           }
   
           idx = nhg_priv_ret->nhg_idx;
           bitmask_free_idx(&ctl->nh_idx_head, idx);
           nhg_priv_ret->nhg_idx = 0;
           nhg_priv_ret->nh_control = NULL;
   
           NHOPS_WUNLOCK(ctl);
   
           IF_DEBUG_LEVEL(LOG_DEBUG2) {
                   char nhgrp_buf[NHOP_PRINT_BUFSIZE];
                   nhgrp_print_buf(nhg_priv_ret->nhg, nhgrp_buf, sizeof(nhgrp_buf));
                   FIB_RH_LOG(LOG_DEBUG2, ctl->ctl_rh, "unlinked idx#%d %s", idx,
                       nhgrp_buf);
           }
   
           return (nhg_priv_ret);
   }
   
   /*
    * Checks if hash needs resizing and performs this resize if necessary
    *
    */
   static void
   consider_resize(struct nh_control *ctl, uint32_t new_gr_bucket, uint32_t new_idx_items)
   {
           void *gr_ptr, *gr_idx_ptr;
           void *old_idx_ptr;
           size_t alloc_size;
   
           gr_ptr = NULL ;
           if (new_gr_bucket != 0) {
                   alloc_size = CHT_SLIST_GET_RESIZE_SIZE(new_gr_bucket);
                   gr_ptr = malloc(alloc_size, M_NHOP, M_NOWAIT | M_ZERO);
           }
   
           gr_idx_ptr = NULL;
           if (new_idx_items != 0) {
                   alloc_size = bitmask_get_size(new_idx_items);
                   gr_idx_ptr = malloc(alloc_size, M_NHOP, M_NOWAIT | M_ZERO);
           }
   
           if (gr_ptr == NULL && gr_idx_ptr == NULL) {
                   /* Either resize is not required or allocations have failed. */
                   return;
           }
   
           FIB_RH_LOG(LOG_DEBUG, ctl->ctl_rh,
               "going to resize nhg hash: [ptr:%p sz:%u] idx:[ptr:%p sz:%u]",
               gr_ptr, new_gr_bucket, gr_idx_ptr, new_idx_items);
   
           old_idx_ptr = NULL;
   
           NHOPS_WLOCK(ctl);
           if (gr_ptr != NULL) {
                   CHT_SLIST_RESIZE(&ctl->gr_head, mpath, gr_ptr, new_gr_bucket);
           }
           if (gr_idx_ptr != NULL) {
                   if (bitmask_copy(&ctl->nh_idx_head, gr_idx_ptr, new_idx_items) == 0)
                           bitmask_swap(&ctl->nh_idx_head, gr_idx_ptr, new_idx_items, &old_idx_ptr);
           }
           NHOPS_WUNLOCK(ctl);
   
           if (gr_ptr != NULL)
                   free(gr_ptr, M_NHOP);
           if (old_idx_ptr != NULL)
                   free(old_idx_ptr, M_NHOP);
   }
   
   /*
    * Function allocating the necessary group data structures.
    */
   bool
   nhgrp_ctl_alloc_default(struct nh_control *ctl, int malloc_flags)
   {
           size_t alloc_size;
           uint32_t num_buckets;
           void *cht_ptr;
   
           malloc_flags = (malloc_flags & (M_NOWAIT | M_WAITOK)) | M_ZERO;
   
           num_buckets = 8;
           alloc_size = CHT_SLIST_GET_RESIZE_SIZE(num_buckets);
           cht_ptr = malloc(alloc_size, M_NHOP, malloc_flags);
   
           if (cht_ptr == NULL) {
                   FIB_RH_LOG(LOG_WARNING, ctl->ctl_rh, "multipath init failed");
                   return (false);
           }
   
           NHOPS_WLOCK(ctl);
   
           if (ctl->gr_head.hash_size == 0) {
                   /* Init hash and bitmask */
                   CHT_SLIST_INIT(&ctl->gr_head, cht_ptr, num_buckets);
                   NHOPS_WUNLOCK(ctl);
           } else {
                   /* Other thread has already initiliazed hash/bitmask */
                   NHOPS_WUNLOCK(ctl);
                   free(cht_ptr, M_NHOP);
           }
   
           FIB_RH_LOG(LOG_DEBUG, ctl->ctl_rh, "multipath init done");
   
           return (true);
   }
   
   int
   nhgrp_ctl_init(struct nh_control *ctl)
   {
   
           /*
            * By default, do not allocate datastructures as multipath
            * routes will not be necessarily used.
            */
           CHT_SLIST_INIT(&ctl->gr_head, NULL, 0);
           return (0);
   }
   
   void
   nhgrp_ctl_free(struct nh_control *ctl)
   {
           if (ctl->gr_head.ptr != NULL)
                   free(ctl->gr_head.ptr, M_NHOP);
   }
   
   void
   nhgrp_ctl_unlink_all(struct nh_control *ctl)
   {
           struct nhgrp_priv *nhg_priv;
   
           NHOPS_WLOCK_ASSERT(ctl);
   
           CHT_SLIST_FOREACH(&ctl->gr_head, mpath, nhg_priv) {
                   IF_DEBUG_LEVEL(LOG_DEBUG2) {
                           char nhgbuf[NHOP_PRINT_BUFSIZE] __unused;
                           FIB_RH_LOG(LOG_DEBUG2, ctl->ctl_rh, "marking %s unlinked",
                               nhgrp_print_buf(nhg_priv->nhg, nhgbuf, sizeof(nhgbuf)));
                   }
                   refcount_release(&nhg_priv->nhg_linked);
           } CHT_SLIST_FOREACH_END;
   }
   

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