Function alloc_nhgrp

freebsd/net/route/nhgrp_ctl.c:254–293

* Allocates new nexthop group for the list of weightened nexthops. * Assume sorted list. * Does NOT reference any nexthops in the group. * Returns group with refcount=1 or NULL. */

 * Returns group with refcount=1 or NULL.
 */
static struct nhgrp_priv *
alloc_nhgrp(struct weightened_nhop *wn, int num_nhops)
{
	uint32_t nhgrp_size;
	int flags = M_NOWAIT;
	struct nhgrp_object *nhg;
	struct nhgrp_priv *nhg_priv;

	nhgrp_size = calc_min_mpath_slots(wn, num_nhops);
	if (nhgrp_size == 0) {
		/* Zero weights, abort */
		return (NULL);
	}

	size_t sz = get_nhgrp_alloc_size(nhgrp_size, num_nhops);
	nhg = malloc(sz, M_NHOP, flags | M_ZERO);
	if (nhg == NULL) {
		return (NULL);
	}

	/* Has to be the first to make NHGRP_PRIV() work */
	nhg->nhg_size = nhgrp_size;
	DPRINTF("new mpath group: num_nhops: %u", (uint32_t)nhgrp_size);
	nhg->nhg_flags = MPF_MULTIPATH;

	nhg_priv = NHGRP_PRIV(nhg);
	nhg_priv->nhg_nh_count = num_nhops;
	refcount_init(&nhg_priv->nhg_refcount, 1);

	/* Please see nhgrp_free() comments on the initial value */
	refcount_init(&nhg_priv->nhg_linked, 2);

	nhg_priv->nhg = nhg;
	memcpy(&nhg_priv->nhg_nh_weights[0], wn,
	  num_nhops * sizeof(struct weightened_nhop));

	compile_nhgrp(nhg_priv, wn, nhg->nhg_size);

	return (nhg_priv);
}

void
nhgrp_ref_object(struct nhgrp_object *nhg)