name_table.c

linux 内核源代码

/*
 * net/tipc/name_table.c: TIPC name table code
 *
 * Copyright (c) 2000-2006, Ericsson AB
 * Copyright (c) 2004-2005, Wind River Systems
 * All rights reserved.
 *
 * 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.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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 "core.h"
#include "config.h"
#include "dbg.h"
#include "name_table.h"
#include "name_distr.h"
#include "addr.h"
#include "node_subscr.h"
#include "subscr.h"
#include "port.h"
#include "cluster.h"
#include "bcast.h"

static int tipc_nametbl_size = 1024;		/* must be a power of 2 */

/**
 * struct sub_seq - container for all published instances of a name sequence
 * @lower: name sequence lower bound
 * @upper: name sequence upper bound
 * @node_list: circular list of matching publications with >= node scope
 * @cluster_list: circular list of matching publications with >= cluster scope
 * @zone_list: circular list of matching publications with >= zone scope
 */

struct sub_seq {
	u32 lower;
	u32 upper;
	struct publication *node_list;
	struct publication *cluster_list;
	struct publication *zone_list;
};

/**
 * struct name_seq - container for all published instances of a name type
 * @type: 32 bit 'type' value for name sequence
 * @sseq: pointer to dynamically-sized array of sub-sequences of this 'type';
 *        sub-sequences are sorted in ascending order
 * @alloc: number of sub-sequences currently in array
 * @first_free: array index of first unused sub-sequence entry
 * @ns_list: links to adjacent name sequences in hash chain
 * @subscriptions: list of subscriptions for this 'type'
 * @lock: spinlock controlling access to name sequence structure
 */

struct name_seq {
	u32 type;
	struct sub_seq *sseqs;
	u32 alloc;
	u32 first_free;
	struct hlist_node ns_list;
	struct list_head subscriptions;
	spinlock_t lock;
};

/**
 * struct name_table - table containing all existing port name publications
 * @types: pointer to fixed-sized array of name sequence lists,
 *         accessed via hashing on 'type'; name sequence lists are *not* sorted
 * @local_publ_count: number of publications issued by this node
 */

struct name_table {
	struct hlist_head *types;
	u32 local_publ_count;
};

static struct name_table table = { NULL } ;
static atomic_t rsv_publ_ok = ATOMIC_INIT(0);
DEFINE_RWLOCK(tipc_nametbl_lock);


static int hash(int x)
{
	return(x & (tipc_nametbl_size - 1));
}

/**
 * publ_create - create a publication structure
 */

static struct publication *publ_create(u32 type, u32 lower, u32 upper,
				       u32 scope, u32 node, u32 port_ref,
				       u32 key)
{
	struct publication *publ = kzalloc(sizeof(*publ), GFP_ATOMIC);
	if (publ == NULL) {
		warn("Publication creation failure, no memory\n");
		return NULL;
	}

	publ->type = type;
	publ->lower = lower;
	publ->upper = upper;
	publ->scope = scope;
	publ->node = node;
	publ->ref = port_ref;
	publ->key = key;
	INIT_LIST_HEAD(&publ->local_list);
	INIT_LIST_HEAD(&publ->pport_list);
	INIT_LIST_HEAD(&publ->subscr.nodesub_list);
	return publ;
}

/**
 * tipc_subseq_alloc - allocate a specified number of sub-sequence structures
 */

static struct sub_seq *tipc_subseq_alloc(u32 cnt)
{
	struct sub_seq *sseq = kcalloc(cnt, sizeof(struct sub_seq), GFP_ATOMIC);
	return sseq;
}

/**
 * tipc_nameseq_create - create a name sequence structure for the specified 'type'
 *
 * Allocates a single sub-sequence structure and sets it to all 0's.
 */

static struct name_seq *tipc_nameseq_create(u32 type, struct hlist_head *seq_head)
{
	struct name_seq *nseq = kzalloc(sizeof(*nseq), GFP_ATOMIC);
	struct sub_seq *sseq = tipc_subseq_alloc(1);

	if (!nseq || !sseq) {
		warn("Name sequence creation failed, no memory\n");
		kfree(nseq);
		kfree(sseq);
		return NULL;
	}

	spin_lock_init(&nseq->lock);
	nseq->type = type;
	nseq->sseqs = sseq;
	dbg("tipc_nameseq_create(): nseq = %p, type %u, ssseqs %p, ff: %u\n",
	    nseq, type, nseq->sseqs, nseq->first_free);
	nseq->alloc = 1;
	INIT_HLIST_NODE(&nseq->ns_list);
	INIT_LIST_HEAD(&nseq->subscriptions);
	hlist_add_head(&nseq->ns_list, seq_head);
	return nseq;
}

/**
 * nameseq_find_subseq - find sub-sequence (if any) matching a name instance
 *
 * Very time-critical, so binary searches through sub-sequence array.
 */

static struct sub_seq *nameseq_find_subseq(struct name_seq *nseq,
					   u32 instance)
{
	struct sub_seq *sseqs = nseq->sseqs;
	int low = 0;
	int high = nseq->first_free - 1;
	int mid;

	while (low <= high) {
		mid = (low + high) / 2;
		if (instance < sseqs[mid].lower)
			high = mid - 1;
		else if (instance > sseqs[mid].upper)
			low = mid + 1;
		else
			return &sseqs[mid];
	}
	return NULL;
}

/**
 * nameseq_locate_subseq - determine position of name instance in sub-sequence
 *
 * Returns index in sub-sequence array of the entry that contains the specified
 * instance value; if no entry contains that value, returns the position
 * where a new entry for it would be inserted in the array.
 *
 * Note: Similar to binary search code for locating a sub-sequence.
 */

static u32 nameseq_locate_subseq(struct name_seq *nseq, u32 instance)
{
	struct sub_seq *sseqs = nseq->sseqs;
	int low = 0;
	int high = nseq->first_free - 1;
	int mid;

	while (low <= high) {
		mid = (low + high) / 2;
		if (instance < sseqs[mid].lower)
			high = mid - 1;
		else if (instance > sseqs[mid].upper)
			low = mid + 1;
		else
			return mid;
	}
	return low;
}

/**
 * tipc_nameseq_insert_publ -
 */

static struct publication *tipc_nameseq_insert_publ(struct name_seq *nseq,
						    u32 type, u32 lower, u32 upper,
						    u32 scope, u32 node, u32 port, u32 key)
{
	struct subscription *s;
	struct subscription *st;
	struct publication *publ;
	struct sub_seq *sseq;
	int created_subseq = 0;

	sseq = nameseq_find_subseq(nseq, lower);
	dbg("nameseq_ins: for seq %p, {%u,%u}, found sseq %p\n",
	    nseq, type, lower, sseq);
	if (sseq) {

		/* Lower end overlaps existing entry => need an exact match */

		if ((sseq->lower != lower) || (sseq->upper != upper)) {
			warn("Cannot publish {%u,%u,%u}, overlap error\n",
			     type, lower, upper);
			return NULL;
		}
	} else {
		u32 inspos;
		struct sub_seq *freesseq;

		/* Find where lower end should be inserted */

		inspos = nameseq_locate_subseq(nseq, lower);

		/* Fail if upper end overlaps into an existing entry */

		if ((inspos < nseq->first_free) &&
		    (upper >= nseq->sseqs[inspos].lower)) {
			warn("Cannot publish {%u,%u,%u}, overlap error\n",
			     type, lower, upper);
			return NULL;
		}

		/* Ensure there is space for new sub-sequence */

		if (nseq->first_free == nseq->alloc) {
			struct sub_seq *sseqs = tipc_subseq_alloc(nseq->alloc * 2);

			if (!sseqs) {
				warn("Cannot publish {%u,%u,%u}, no memory\n",
				     type, lower, upper);
				return NULL;
			}
			dbg("Allocated %u more sseqs\n", nseq->alloc);
			memcpy(sseqs, nseq->sseqs,
			       nseq->alloc * sizeof(struct sub_seq));
			kfree(nseq->sseqs);
			nseq->sseqs = sseqs;
			nseq->alloc *= 2;
		}
		dbg("Have %u sseqs for type %u\n", nseq->alloc, type);

		/* Insert new sub-sequence */

		dbg("ins in pos %u, ff = %u\n", inspos, nseq->first_free);
		sseq = &nseq->sseqs[inspos];
		freesseq = &nseq->sseqs[nseq->first_free];
		memmove(sseq + 1, sseq, (freesseq - sseq) * sizeof (*sseq));
		memset(sseq, 0, sizeof (*sseq));
		nseq->first_free++;
		sseq->lower = lower;
		sseq->upper = upper;
		created_subseq = 1;
	}
	dbg("inserting {%u,%u,%u} from <0x%x:%u> into sseq %p(%u,%u) of seq %p\n",
	    type, lower, upper, node, port, sseq,
	    sseq->lower, sseq->upper, nseq);

	/* Insert a publication: */

	publ = publ_create(type, lower, upper, scope, node, port, key);
	if (!publ)
		return NULL;
	dbg("inserting publ %p, node=0x%x publ->node=0x%x, subscr->node=%p\n",
	    publ, node, publ->node, publ->subscr.node);

	if (!sseq->zone_list)
		sseq->zone_list = publ->zone_list_next = publ;
	else {
		publ->zone_list_next = sseq->zone_list->zone_list_next;
		sseq->zone_list->zone_list_next = publ;
	}

	if (in_own_cluster(node)) {
		if (!sseq->cluster_list)
			sseq->cluster_list = publ->cluster_list_next = publ;
		else {
			publ->cluster_list_next =
			sseq->cluster_list->cluster_list_next;
			sseq->cluster_list->cluster_list_next = publ;
		}
	}

	if (node == tipc_own_addr) {
		if (!sseq->node_list)
			sseq->node_list = publ->node_list_next = publ;
		else {
			publ->node_list_next = sseq->node_list->node_list_next;
			sseq->node_list->node_list_next = publ;
		}
	}

	/*
	 * Any subscriptions waiting for notification?
	 */
	list_for_each_entry_safe(s, st, &nseq->subscriptions, nameseq_list) {
		dbg("calling report_overlap()\n");
		tipc_subscr_report_overlap(s,
					   publ->lower,
					   publ->upper,
					   TIPC_PUBLISHED,
					   publ->ref,
					   publ->node,
					   created_subseq);
	}
	return publ;
}

/**
 * tipc_nameseq_remove_publ -
 *
 * NOTE: There may be cases where TIPC is asked to remove a publication
 * that is not in the name table.  For example, if another node issues a
 * publication for a name sequence that overlaps an existing name sequence
 * the publication will not be recorded, which means the publication won't
 * be found when the name sequence is later withdrawn by that node.
 * A failed withdraw request simply returns a failure indication and lets the
 * caller issue any error or warning messages associated with such a problem.
 */

static struct publication *tipc_nameseq_remove_publ(struct name_seq *nseq, u32 inst,
						    u32 node, u32 ref, u32 key)
{
	struct publication *publ;
	struct publication *curr;
	struct publication *prev;
	struct sub_seq *sseq = nameseq_find_subseq(nseq, inst);
	struct sub_seq *free;
	struct subscription *s, *st;
	int removed_subseq = 0;

	if (!sseq)
		return NULL;

	dbg("tipc_nameseq_remove_publ: seq: %p, sseq %p, {%u,%u}, key %u\n",
	    nseq, sseq, nseq->type, inst, key);

	/* Remove publication from zone scope list */

	prev = sseq->zone_list;
	publ = sseq->zone_list->zone_list_next;
	while ((publ->key != key) || (publ->ref != ref) ||
	       (publ->node && (publ->node != node))) {
		prev = publ;
		publ = publ->zone_list_next;
		if (prev == sseq->zone_list) {

			/* Prevent endless loop if publication not found */

			return NULL;
		}
	}
	if (publ != sseq->zone_list)
		prev->zone_list_next = publ->zone_list_next;
	else if (publ->zone_list_next != publ) {
		prev->zone_list_next = publ->zone_list_next;
		sseq->zone_list = publ->zone_list_next;
	} else {
		sseq->zone_list = NULL;
	}

	/* Remove publication from cluster scope list, if present */

	if (in_own_cluster(node)) {
		prev = sseq->cluster_list;
		curr = sseq->cluster_list->cluster_list_next;
		while (curr != publ) {
			prev = curr;
			curr = curr->cluster_list_next;
			if (prev == sseq->cluster_list) {

				/* Prevent endless loop for malformed list */

				err("Unable to de-list cluster publication\n"
				    "{%u%u}, node=0x%x, ref=%u, key=%u)\n",
				    publ->type, publ->lower, publ->node,
				    publ->ref, publ->key);
				goto end_cluster;
			}
		}
		if (publ != sseq->cluster_list)
			prev->cluster_list_next = publ->cluster_list_next;
		else if (publ->cluster_list_next != publ) {
			prev->cluster_list_next = publ->cluster_list_next;
			sseq->cluster_list = publ->cluster_list_next;
		} else {
			sseq->cluster_list = NULL;
		}
	}
end_cluster:

	/* Remove publication from node scope list, if present */

	if (node == tipc_own_addr) {
		prev = sseq->node_list;
		curr = sseq->node_list->node_list_next;
		while (curr != publ) {
			prev = curr;
			curr = curr->node_list_next;
			if (prev == sseq->node_list) {

				/* Prevent endless loop for malformed list */

				err("Unable to de-list node publication\n"
				    "{%u%u}, node=0x%x, ref=%u, key=%u)\n",
				    publ->type, publ->lower, publ->node,
				    publ->ref, publ->key);
				goto end_node;
			}
		}
		if (publ != sseq->node_list)
			prev->node_list_next = publ->node_list_next;
		else if (publ->node_list_next != publ) {
			prev->node_list_next = publ->node_list_next;
			sseq->node_list = publ->node_list_next;
		} else {
			sseq->node_list = NULL;
		}
	}
end_node:

	/* Contract subseq list if no more publications for that subseq */

	if (!sseq->zone_list) {
		free = &nseq->sseqs[nseq->first_free--];
		memmove(sseq, sseq + 1, (free - (sseq + 1)) * sizeof (*sseq));
		removed_subseq = 1;
	}

	/* Notify any waiting subscriptions */

	list_for_each_entry_safe(s, st, &nseq->subscriptions, nameseq_list) {
		tipc_subscr_report_overlap(s,
					   publ->lower,
					   publ->upper,
					   TIPC_WITHDRAWN,
					   publ->ref,
					   publ->node,
					   removed_subseq);
	}

	return publ;
}

/**
 * tipc_nameseq_subscribe: attach a subscription, and issue
 * the prescribed number of events if there is any sub-
 * sequence overlapping with the requested sequence
 */

static void tipc_nameseq_subscribe(struct name_seq *nseq, struct subscription *s)
{
	struct sub_seq *sseq = nseq->sseqs;

	list_add(&s->nameseq_list, &nseq->subscriptions);

	if (!sseq)
		return;

	while (sseq != &nseq->sseqs[nseq->first_free]) {
		struct publication *zl = sseq->zone_list;
		if (zl && tipc_subscr_overlap(s,sseq->lower,sseq->upper)) {
			struct publication *crs = zl;
			int must_report = 1;

			do {
				tipc_subscr_report_overlap(s,
							   sseq->lower,
							   sseq->upper,
							   TIPC_PUBLISHED,
							   crs->ref,
							   crs->node,
							   must_report);
				must_report = 0;
				crs = crs->zone_list_next;
			} while (crs != zl);
		}
		sseq++;
	}
}

static struct name_seq *nametbl_find_seq(u32 type)
{
	struct hlist_head *seq_head;
	struct hlist_node *seq_node;
	struct name_seq *ns;

	dbg("find_seq %u,(%u,0x%x) table = %p, hash[type] = %u\n",
	    type, ntohl(type), type, table.types, hash(type));