- 根目录:
- net
- tipc
- subscr.c
/*
* net/tipc/subscr.c: TIPC network topology service
*
* Copyright (c) 2000-2006, Ericsson AB
* Copyright (c) 2005-2007, 2010-2011, 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 "name_table.h"
#include "port.h"
#include "subscr.h"
/**
* struct subscriber - TIPC network topology subscriber
* @port_ref: object reference to server port connecting to subscriber
* @lock: pointer to spinlock controlling access to subscriber's server port
* @subscriber_list: adjacent subscribers in top. server's list of subscribers
* @subscription_list: list of subscription objects for this subscriber
*/
struct subscriber {
u32 port_ref;
spinlock_t *lock;
struct list_head subscriber_list;
struct list_head subscription_list;
};
/**
* struct top_srv - TIPC network topology subscription service
* @user_ref: TIPC userid of subscription service
* @setup_port: reference to TIPC port that handles subscription requests
* @subscription_count: number of active subscriptions (not subscribers!)
* @subscriber_list: list of ports subscribing to service
* @lock: spinlock govering access to subscriber list
*/
struct top_srv {
u32 setup_port;
atomic_t subscription_count;
struct list_head subscriber_list;
spinlock_t lock;
};
static struct top_srv topsrv;
/**
* htohl - convert value to endianness used by destination
* @in: value to convert
* @swap: non-zero if endianness must be reversed
*
* Returns converted value
*/
static u32 htohl(u32 in, int swap)
{
return swap ? swab32(in) : in;
}
/**
* subscr_send_event - send a message containing a tipc_event to the subscriber
*
* Note: Must not hold subscriber's server port lock, since tipc_send() will
* try to take the lock if the message is rejected and returned!
*/
static void subscr_send_event(struct subscription *sub,
u32 found_lower,
u32 found_upper,
u32 event,
u32 port_ref,
u32 node)
{
struct iovec msg_sect;
msg_sect.iov_base = (void *)&sub->evt;
msg_sect.iov_len = sizeof(struct tipc_event);
sub->evt.event = htohl(event, sub->swap);
sub->evt.found_lower = htohl(found_lower, sub->swap);
sub->evt.found_upper = htohl(found_upper, sub->swap);
sub->evt.port.ref = htohl(port_ref, sub->swap);
sub->evt.port.node = htohl(node, sub->swap);
tipc_send(sub->server_ref, 1, &msg_sect);
}
/**
* tipc_subscr_overlap - test for subscription overlap with the given values
*
* Returns 1 if there is overlap, otherwise 0.
*/
int tipc_subscr_overlap(struct subscription *sub,
u32 found_lower,
u32 found_upper)
{
if (found_lower < sub->seq.lower)
found_lower = sub->seq.lower;
if (found_upper > sub->seq.upper)
found_upper = sub->seq.upper;
if (found_lower > found_upper)
return 0;
return 1;
}
/**
* tipc_subscr_report_overlap - issue event if there is subscription overlap
*
* Protected by nameseq.lock in name_table.c
*/
void tipc_subscr_report_overlap(struct subscription *sub,
u32 found_lower,
u32 found_upper,
u32 event,
u32 port_ref,
u32 node,
int must)
{
if (!tipc_subscr_overlap(sub, found_lower, found_upper))
return;
if (!must && !(sub->filter & TIPC_SUB_PORTS))
return;
sub->event_cb(sub, found_lower, found_upper, event, port_ref, node);
}
/**
* subscr_timeout - subscription timeout has occurred
*/
static void subscr_timeout(struct subscription *sub)
{
struct tipc_port *server_port;
/* Validate server port reference (in case subscriber is terminating) */
server_port = tipc_port_lock(sub->server_ref);
if (server_port == NULL)
return;
/* Validate timeout (in case subscription is being cancelled) */
if (sub->timeout == TIPC_WAIT_FOREVER) {
tipc_port_unlock(server_port);
return;
}
/* Unlink subscription from name table */
tipc_nametbl_unsubscribe(sub);
/* Unlink subscription from subscriber */
list_del(&sub->subscription_list);
/* Release subscriber's server port */
tipc_port_unlock(server_port);
/* Notify subscriber of timeout */
subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
TIPC_SUBSCR_TIMEOUT, 0, 0);
/* Now destroy subscription */
k_term_timer(&sub->timer);
kfree(sub);
atomic_dec(&topsrv.subscription_count);
}
/**
* subscr_del - delete a subscription within a subscription list
*
* Called with subscriber port locked.
*/
static void subscr_del(struct subscription *sub)
{
tipc_nametbl_unsubscribe(sub);
list_del(&sub->subscription_list);
kfree(sub);
atomic_dec(&topsrv.subscription_count);
}
/**
* subscr_terminate - terminate communication with a subscriber
*
* Called with subscriber port locked. Routine must temporarily release lock
* to enable subscription timeout routine(s) to finish without deadlocking;
* the lock is then reclaimed to allow caller to release it upon return.
* (This should work even in the unlikely event some other thread creates
* a new object reference in the interim that uses this lock; this routine will
* simply wait for it to be released, then claim it.)
*/
static void subscr_terminate(struct subscriber *subscriber)
{
u32 port_ref;
struct subscription *sub;
struct subscription *sub_temp;
/* Invalidate subscriber reference */
port_ref = subscriber->port_ref;
subscriber->port_ref = 0;
spin_unlock_bh(subscriber->lock);
/* Sever connection to subscriber */
tipc_shutdown(port_ref);
tipc_deleteport(port_ref);
/* Destroy any existing subscriptions for subscriber */
list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
subscription_list) {
if (sub->timeout != TIPC_WAIT_FOREVER) {
k_cancel_timer(&sub->timer);
k_term_timer(&sub->timer);
}
subscr_del(sub);
}
/* Remove subscriber from topology server's subscriber list */
spin_lock_bh(&topsrv.lock);
list_del(&subscriber->subscriber_list);
spin_unlock_bh(&topsrv.lock);
/* Reclaim subscriber lock */
spin_lock_bh(subscriber->lock);
/* Now destroy subscriber */
kfree(subscriber);
}
/**
* subscr_cancel - handle subscription cancellation request
*
* Called with subscriber port locked. Routine must temporarily release lock
* to enable the subscription timeout routine to finish without deadlocking;
* the lock is then reclaimed to allow caller to release it upon return.
*
* Note that fields of 's' use subscriber's endianness!
*/
static void subscr_cancel(struct tipc_subscr *s,
struct subscriber *subscriber)
{
struct subscription *sub;
struct subscription *sub_temp;
int found = 0;
/* Find first matching subscription, exit if not found */
list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
subscription_list) {
if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
found = 1;
break;
}
}
if (!found)
return;
/* Cancel subscription timer (if used), then delete subscription */
if (sub->timeout != TIPC_WAIT_FOREVER) {
sub->timeout = TIPC_WAIT_FOREVER;
spin_unlock_bh(subscriber->lock);
k_cancel_timer(&sub->timer);
k_term_timer(&sub->timer);
spin_lock_bh(subscriber->lock);
}
subscr_del(sub);
}
/**
* subscr_subscribe - create subscription for subscriber
*
* Called with subscriber port locked.
*/
static struct subscription *subscr_subscribe(struct tipc_subscr *s,
struct subscriber *subscriber)
{
struct subscription *sub;
int swap;
/* Determine subscriber's endianness */
swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
/* Detect & process a subscription cancellation request */
if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
subscr_cancel(s, subscriber);
return NULL;
}
/* Refuse subscription if global limit exceeded */
if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
warn("Subscription rejected, subscription limit reached (%u)\n",
tipc_max_subscriptions);
subscr_terminate(subscriber);
return NULL;
}
/* Allocate subscription object */
sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
if (!sub) {
warn("Subscription rejected, no memory\n");
subscr_terminate(subscriber);
return NULL;
}
/* Initialize subscription object */
sub->seq.type = htohl(s->seq.type, swap);
sub->seq.lower = htohl(s->seq.lower, swap);
sub->seq.upper = htohl(s->seq.upper, swap);
sub->timeout = htohl(s->timeout, swap);
sub->filter = htohl(s->filter, swap);
if ((!(sub->filter & TIPC_SUB_PORTS) ==
!(sub->filter & TIPC_SUB_SERVICE)) ||
(sub->seq.lower > sub->seq.upper)) {
warn("Subscription rejected, illegal request\n");
kfree(sub);
subscr_terminate(subscriber);
return NULL;
}
sub->event_cb = subscr_send_event;
INIT_LIST_HEAD(&sub->nameseq_list);
list_add(&sub->subscription_list, &subscriber->subscription_list);
sub->server_ref = subscriber->port_ref;
sub->swap = swap;
memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
atomic_inc(&topsrv.subscription_count);
if (sub->timeout != TIPC_WAIT_FOREVER) {
k_init_timer(&sub->timer,
(Handler)subscr_timeout, (unsigned long)sub);
k_start_timer(&sub->timer, sub->timeout);
}
return sub;
}
/**
* subscr_conn_shutdown_event - handle termination request from subscriber
*
* Called with subscriber's server port unlocked.
*/
static void subscr_conn_shutdown_event(void *usr_handle,
u32 port_ref,
struct sk_buff **buf,
unsigned char const *data,
unsigned int size,
int reason)
{
struct subscriber *subscriber = usr_handle;
spinlock_t *subscriber_lock;
if (tipc_port_lock(port_ref) == NULL)
return;
subscriber_lock = subscriber->lock;
subscr_terminate(subscriber);
spin_unlock_bh(subscriber_lock);
}
/**
* subscr_conn_msg_event - handle new subscription request from subscriber
*
* Called with subscriber's server port unlocked.
*/
static void subscr_conn_msg_event(void *usr_handle,
u32 port_ref,
struct sk_buff **buf,
const unchar *data,
u32 size)
{
struct subscriber *subscriber = usr_handle;
spinlock_t *subscriber_lock;
struct subscription *sub;
/*
* Lock subscriber's server port (& make a local copy of lock pointer,
* in case subscriber is deleted while processing subscription request)
*/
if (tipc_port_lock(port_ref) == NULL)
return;
subscriber_lock = subscriber->lock;
if (size != sizeof(struct tipc_subscr)) {
subscr_terminate(subscriber);
spin_unlock_bh(subscriber_lock);
} else {
sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
spin_unlock_bh(subscriber_lock);
if (sub != NULL) {
/*
* We must release the server port lock before adding a
* subscription to the name table since TIPC needs to be
* able to (re)acquire the port lock if an event message
* issued by the subscription process is rejected and
* returned. The subscription cannot be deleted while
* it is being added to the name table because:
* a) the single-threading of the native API port code
* ensures the subscription cannot be cancelled and
* the subscriber connection cannot be broken, and
* b) the name table lock ensures the subscription
* timeout code cannot delete the subscription,
* so the subscription object is still protected.
*/
tipc_nametbl_subscribe(sub);
}
}
}
/**
* subscr_named_msg_event - handle request to establish a new subscriber
*/
static void subscr_named_msg_event(void *usr_handle,
u32 port_ref,
struct sk_buff **buf,
const unchar *data,
u32 size,
u32 importance,
struct tipc_portid const *orig,
struct tipc_name_seq const *dest)
{
struct subscriber *subscriber;
u32 server_port_ref;
/* Create subscriber object */
subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
if (subscriber == NULL) {
warn("Subscriber rejected, no memory\n");
return;
}
INIT_LIST_HEAD(&subscriber->subscription_list);
INIT_LIST_HEAD(&subscriber->subscriber_list);
/* Create server port & establish connection to subscriber */
tipc_createport(subscriber,
importance,
NULL,
NULL,
subscr_conn_shutdown_event,
NULL,
NULL,
subscr_conn_msg_event,
NULL,
&subscriber->port_ref);
if (subscriber->port_ref == 0) {
warn("Subscriber rejected, unable to create port\n");
kfree(subscriber);
return;
}
tipc_connect2port(subscriber->port_ref, orig);
/* Lock server port (& save lock address for future use) */
subscriber->lock = tipc_port_lock(subscriber->port_ref)->lock;
/* Add subscriber to topology server's subscriber list */
spin_lock_bh(&topsrv.lock);
list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
spin_unlock_bh(&topsrv.lock);
/* Unlock server port */
server_port_ref = subscriber->port_ref;
spin_unlock_bh(subscriber->lock);
/* Send an ACK- to complete connection handshaking */
tipc_send(server_port_ref, 0, NULL);
/* Handle optional subscription request */
if (size != 0) {
subscr_conn_msg_event(subscriber, server_port_ref,
buf, data, size);
}
}
int tipc_subscr_start(void)
{
struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
int res;
memset(&topsrv, 0, sizeof(topsrv));
spin_lock_init(&topsrv.lock);
INIT_LIST_HEAD(&topsrv.subscriber_list);
res = tipc_createport(NULL,
TIPC_CRITICAL_IMPORTANCE,
NULL,
NULL,
NULL,
NULL,
subscr_named_msg_event,
NULL,
NULL,
&topsrv.setup_port);
if (res)
goto failed;
res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
if (res) {
tipc_deleteport(topsrv.setup_port);
topsrv.setup_port = 0;
goto failed;
}
return 0;
failed:
err("Failed to create subscription service\n");
return res;
}
void tipc_subscr_stop(void)
{
struct subscriber *subscriber;
struct subscriber *subscriber_temp;
spinlock_t *subscriber_lock;
if (topsrv.setup_port) {
tipc_deleteport(topsrv.setup_port);
topsrv.setup_port = 0;
list_for_each_entry_safe(subscriber, subscriber_temp,
&topsrv.subscriber_list,
subscriber_list) {
subscriber_lock = subscriber->lock;
spin_lock_bh(subscriber_lock);
subscr_terminate(subscriber);
spin_unlock_bh(subscriber_lock);
}
}
}