linux/net/tipc/subscr.c
Ying Xue 7efea60dcf tipc: adjust the policy of holding subscription kref
When a new subscription object is inserted into name_seq->subscriptions
list, it's under name_seq->lock protection; when a subscription is
deleted from the list, it's also under the same lock protection;
similarly, when accessing a subscription by going through subscriptions
list, the entire process is also protected by the name_seq->lock.

Therefore, if subscription refcount is increased before it's inserted
into subscriptions list, and its refcount is decreased after it's
deleted from the list, it will be unnecessary to hold refcount at all
before accessing subscription object which is obtained by going through
subscriptions list under name_seq->lock protection.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-28 18:03:33 -07:00

397 lines
12 KiB
C

/*
* net/tipc/subscr.c: TIPC network topology service
*
* Copyright (c) 2000-2006, Ericsson AB
* Copyright (c) 2005-2007, 2010-2013, 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 "subscr.h"
/**
* struct tipc_subscriber - TIPC network topology subscriber
* @kref: reference counter to tipc_subscription object
* @conid: connection identifier to server connecting to subscriber
* @lock: control access to subscriber
* @subscrp_list: list of subscription objects for this subscriber
*/
struct tipc_subscriber {
struct kref kref;
int conid;
spinlock_t lock;
struct list_head subscrp_list;
};
static void tipc_subscrp_delete(struct tipc_subscription *sub);
static void tipc_subscrb_put(struct tipc_subscriber *subscriber);
/**
* 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;
}
static void tipc_subscrp_send_event(struct tipc_subscription *sub,
u32 found_lower, u32 found_upper,
u32 event, u32 port_ref, u32 node)
{
struct tipc_net *tn = net_generic(sub->net, tipc_net_id);
struct tipc_subscriber *subscriber = sub->subscriber;
struct kvec 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_conn_sendmsg(tn->topsrv, subscriber->conid, NULL,
msg_sect.iov_base, msg_sect.iov_len);
}
/**
* tipc_subscrp_check_overlap - test for subscription overlap with the
* given values
*
* Returns 1 if there is overlap, otherwise 0.
*/
int tipc_subscrp_check_overlap(struct tipc_name_seq *seq, u32 found_lower,
u32 found_upper)
{
if (found_lower < seq->lower)
found_lower = seq->lower;
if (found_upper > seq->upper)
found_upper = seq->upper;
if (found_lower > found_upper)
return 0;
return 1;
}
u32 tipc_subscrp_convert_seq_type(u32 type, int swap)
{
return htohl(type, swap);
}
void tipc_subscrp_convert_seq(struct tipc_name_seq *in, int swap,
struct tipc_name_seq *out)
{
out->type = htohl(in->type, swap);
out->lower = htohl(in->lower, swap);
out->upper = htohl(in->upper, swap);
}
void tipc_subscrp_report_overlap(struct tipc_subscription *sub, u32 found_lower,
u32 found_upper, u32 event, u32 port_ref,
u32 node, int must)
{
struct tipc_name_seq seq;
tipc_subscrp_convert_seq(&sub->evt.s.seq, sub->swap, &seq);
if (!tipc_subscrp_check_overlap(&seq, found_lower, found_upper))
return;
if (!must &&
!(htohl(sub->evt.s.filter, sub->swap) & TIPC_SUB_PORTS))
return;
tipc_subscrp_send_event(sub, found_lower, found_upper, event, port_ref,
node);
}
static void tipc_subscrp_timeout(unsigned long data)
{
struct tipc_subscription *sub = (struct tipc_subscription *)data;
struct tipc_subscriber *subscriber = sub->subscriber;
spin_lock_bh(&subscriber->lock);
tipc_nametbl_unsubscribe(sub);
list_del(&sub->subscrp_list);
spin_unlock_bh(&subscriber->lock);
/* Notify subscriber of timeout */
tipc_subscrp_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
TIPC_SUBSCR_TIMEOUT, 0, 0);
tipc_subscrp_put(sub);
}
static void tipc_subscrb_kref_release(struct kref *kref)
{
kfree(container_of(kref,struct tipc_subscriber, kref));
}
static void tipc_subscrb_put(struct tipc_subscriber *subscriber)
{
kref_put(&subscriber->kref, tipc_subscrb_kref_release);
}
static void tipc_subscrb_get(struct tipc_subscriber *subscriber)
{
kref_get(&subscriber->kref);
}
static void tipc_subscrp_kref_release(struct kref *kref)
{
struct tipc_subscription *sub = container_of(kref,
struct tipc_subscription,
kref);
struct tipc_net *tn = net_generic(sub->net, tipc_net_id);
struct tipc_subscriber *subscriber = sub->subscriber;
atomic_dec(&tn->subscription_count);
kfree(sub);
tipc_subscrb_put(subscriber);
}
void tipc_subscrp_put(struct tipc_subscription *subscription)
{
kref_put(&subscription->kref, tipc_subscrp_kref_release);
}
void tipc_subscrp_get(struct tipc_subscription *subscription)
{
kref_get(&subscription->kref);
}
/* tipc_subscrb_subscrp_delete - delete a specific subscription or all
* subscriptions for a given subscriber.
*/
static void tipc_subscrb_subscrp_delete(struct tipc_subscriber *subscriber,
struct tipc_subscr *s)
{
struct list_head *subscription_list = &subscriber->subscrp_list;
struct tipc_subscription *sub, *temp;
spin_lock_bh(&subscriber->lock);
list_for_each_entry_safe(sub, temp, subscription_list, subscrp_list) {
if (s && memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr)))
continue;
tipc_nametbl_unsubscribe(sub);
list_del(&sub->subscrp_list);
tipc_subscrp_delete(sub);
if (s)
break;
}
spin_unlock_bh(&subscriber->lock);
}
static struct tipc_subscriber *tipc_subscrb_create(int conid)
{
struct tipc_subscriber *subscriber;
subscriber = kzalloc(sizeof(*subscriber), GFP_ATOMIC);
if (!subscriber) {
pr_warn("Subscriber rejected, no memory\n");
return NULL;
}
INIT_LIST_HEAD(&subscriber->subscrp_list);
kref_init(&subscriber->kref);
subscriber->conid = conid;
spin_lock_init(&subscriber->lock);
return subscriber;
}
static void tipc_subscrb_delete(struct tipc_subscriber *subscriber)
{
tipc_subscrb_subscrp_delete(subscriber, NULL);
tipc_subscrb_put(subscriber);
}
static void tipc_subscrp_delete(struct tipc_subscription *sub)
{
u32 timeout = htohl(sub->evt.s.timeout, sub->swap);
if (timeout == TIPC_WAIT_FOREVER || del_timer(&sub->timer))
tipc_subscrp_put(sub);
}
static void tipc_subscrp_cancel(struct tipc_subscr *s,
struct tipc_subscriber *subscriber)
{
tipc_subscrb_subscrp_delete(subscriber, s);
}
static struct tipc_subscription *tipc_subscrp_create(struct net *net,
struct tipc_subscr *s,
int swap)
{
struct tipc_net *tn = net_generic(net, tipc_net_id);
struct tipc_subscription *sub;
u32 filter = htohl(s->filter, swap);
/* Refuse subscription if global limit exceeded */
if (atomic_read(&tn->subscription_count) >= TIPC_MAX_SUBSCRIPTIONS) {
pr_warn("Subscription rejected, limit reached (%u)\n",
TIPC_MAX_SUBSCRIPTIONS);
return NULL;
}
/* Allocate subscription object */
sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
if (!sub) {
pr_warn("Subscription rejected, no memory\n");
return NULL;
}
/* Initialize subscription object */
sub->net = net;
if (((filter & TIPC_SUB_PORTS) && (filter & TIPC_SUB_SERVICE)) ||
(htohl(s->seq.lower, swap) > htohl(s->seq.upper, swap))) {
pr_warn("Subscription rejected, illegal request\n");
kfree(sub);
return NULL;
}
sub->swap = swap;
memcpy(&sub->evt.s, s, sizeof(*s));
atomic_inc(&tn->subscription_count);
kref_init(&sub->kref);
return sub;
}
static void tipc_subscrp_subscribe(struct net *net, struct tipc_subscr *s,
struct tipc_subscriber *subscriber, int swap)
{
struct tipc_net *tn = net_generic(net, tipc_net_id);
struct tipc_subscription *sub = NULL;
u32 timeout;
sub = tipc_subscrp_create(net, s, swap);
if (!sub)
return tipc_conn_terminate(tn->topsrv, subscriber->conid);
spin_lock_bh(&subscriber->lock);
list_add(&sub->subscrp_list, &subscriber->subscrp_list);
sub->subscriber = subscriber;
tipc_nametbl_subscribe(sub);
tipc_subscrb_get(subscriber);
spin_unlock_bh(&subscriber->lock);
setup_timer(&sub->timer, tipc_subscrp_timeout, (unsigned long)sub);
timeout = htohl(sub->evt.s.timeout, swap);
if (timeout != TIPC_WAIT_FOREVER)
mod_timer(&sub->timer, jiffies + msecs_to_jiffies(timeout));
}
/* Handle one termination request for the subscriber */
static void tipc_subscrb_release_cb(int conid, void *usr_data)
{
tipc_subscrb_delete((struct tipc_subscriber *)usr_data);
}
/* Handle one request to create a new subscription for the subscriber */
static void tipc_subscrb_rcv_cb(struct net *net, int conid,
struct sockaddr_tipc *addr, void *usr_data,
void *buf, size_t len)
{
struct tipc_subscriber *subscriber = usr_data;
struct tipc_subscr *s = (struct tipc_subscr *)buf;
int swap;
/* Determine subscriber's endianness */
swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE |
TIPC_SUB_CANCEL));
/* Detect & process a subscription cancellation request */
if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
return tipc_subscrp_cancel(s, subscriber);
}
tipc_subscrp_subscribe(net, s, subscriber, swap);
}
/* Handle one request to establish a new subscriber */
static void *tipc_subscrb_connect_cb(int conid)
{
return (void *)tipc_subscrb_create(conid);
}
int tipc_topsrv_start(struct net *net)
{
struct tipc_net *tn = net_generic(net, tipc_net_id);
const char name[] = "topology_server";
struct tipc_server *topsrv;
struct sockaddr_tipc *saddr;
saddr = kzalloc(sizeof(*saddr), GFP_ATOMIC);
if (!saddr)
return -ENOMEM;
saddr->family = AF_TIPC;
saddr->addrtype = TIPC_ADDR_NAMESEQ;
saddr->addr.nameseq.type = TIPC_TOP_SRV;
saddr->addr.nameseq.lower = TIPC_TOP_SRV;
saddr->addr.nameseq.upper = TIPC_TOP_SRV;
saddr->scope = TIPC_NODE_SCOPE;
topsrv = kzalloc(sizeof(*topsrv), GFP_ATOMIC);
if (!topsrv) {
kfree(saddr);
return -ENOMEM;
}
topsrv->net = net;
topsrv->saddr = saddr;
topsrv->imp = TIPC_CRITICAL_IMPORTANCE;
topsrv->type = SOCK_SEQPACKET;
topsrv->max_rcvbuf_size = sizeof(struct tipc_subscr);
topsrv->tipc_conn_recvmsg = tipc_subscrb_rcv_cb;
topsrv->tipc_conn_new = tipc_subscrb_connect_cb;
topsrv->tipc_conn_release = tipc_subscrb_release_cb;
strncpy(topsrv->name, name, strlen(name) + 1);
tn->topsrv = topsrv;
atomic_set(&tn->subscription_count, 0);
return tipc_server_start(topsrv);
}
void tipc_topsrv_stop(struct net *net)
{
struct tipc_net *tn = net_generic(net, tipc_net_id);
struct tipc_server *topsrv = tn->topsrv;
tipc_server_stop(topsrv);
kfree(topsrv->saddr);
kfree(topsrv);
}