linux_dsm_epyc7002/net/tipc/subscr.c

401 lines
12 KiB
C
Raw Normal View History

/*
* net/tipc/subscr.c: TIPC network topology service
*
* Copyright (c) 2000-2006, Ericsson AB
tipc: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
* 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
tipc: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
* @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;
tipc: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
int conid;
spinlock_t lock;
struct list_head subscrp_list;
};
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);
tipc: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
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, u32 scope, int must)
{
u32 filter = htohl(sub->evt.s.filter, sub->swap);
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 && !(filter & TIPC_SUB_PORTS))
return;
if (filter & TIPC_SUB_CLUSTER_SCOPE && scope == TIPC_NODE_SCOPE)
return;
if (filter & TIPC_SUB_NODE_SCOPE && scope != TIPC_NODE_SCOPE)
return;
tipc_subscrp_send_event(sub, found_lower, found_upper, event, port_ref,
node);
}
static void tipc_subscrp_timeout(struct timer_list *t)
{
struct tipc_subscription *sub = from_timer(sub, t, timer);
tipc: fix nametbl deadlock at tipc_nametbl_unsubscribe Until now, tipc_nametbl_unsubscribe() is called at subscriptions reference count cleanup. Usually the subscriptions cleanup is called at subscription timeout or at subscription cancel or at subscriber delete. We have ignored the possibility of this being called from other locations, which causes deadlock as we try to grab the tn->nametbl_lock while holding it already. CPU1: CPU2: ---------- ---------------- tipc_nametbl_publish spin_lock_bh(&tn->nametbl_lock) tipc_nametbl_insert_publ tipc_nameseq_insert_publ tipc_subscrp_report_overlap tipc_subscrp_get tipc_subscrp_send_event tipc_close_conn tipc_subscrb_release_cb tipc_subscrb_delete tipc_subscrp_put tipc_subscrp_put tipc_subscrp_kref_release tipc_nametbl_unsubscribe spin_lock_bh(&tn->nametbl_lock) <<grab nametbl_lock again>> CPU1: CPU2: ---------- ---------------- tipc_nametbl_stop spin_lock_bh(&tn->nametbl_lock) tipc_purge_publications tipc_nameseq_remove_publ tipc_subscrp_report_overlap tipc_subscrp_get tipc_subscrp_send_event tipc_close_conn tipc_subscrb_release_cb tipc_subscrb_delete tipc_subscrp_put tipc_subscrp_put tipc_subscrp_kref_release tipc_nametbl_unsubscribe spin_lock_bh(&tn->nametbl_lock) <<grab nametbl_lock again>> In this commit, we advance the calling of tipc_nametbl_unsubscribe() from the refcount cleanup to the intended callers. Fixes: d094c4d5f5c7 ("tipc: add subscription refcount to avoid invalid delete") Reported-by: John Thompson <thompa.atl@gmail.com> Acked-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-21 16:47:49 +07:00
struct tipc_subscriber *subscriber = sub->subscriber;
spin_lock_bh(&subscriber->lock);
tipc_nametbl_unsubscribe(sub);
list_del(&sub->subscrp_list);
tipc: fix nametbl deadlock at tipc_nametbl_unsubscribe Until now, tipc_nametbl_unsubscribe() is called at subscriptions reference count cleanup. Usually the subscriptions cleanup is called at subscription timeout or at subscription cancel or at subscriber delete. We have ignored the possibility of this being called from other locations, which causes deadlock as we try to grab the tn->nametbl_lock while holding it already. CPU1: CPU2: ---------- ---------------- tipc_nametbl_publish spin_lock_bh(&tn->nametbl_lock) tipc_nametbl_insert_publ tipc_nameseq_insert_publ tipc_subscrp_report_overlap tipc_subscrp_get tipc_subscrp_send_event tipc_close_conn tipc_subscrb_release_cb tipc_subscrb_delete tipc_subscrp_put tipc_subscrp_put tipc_subscrp_kref_release tipc_nametbl_unsubscribe spin_lock_bh(&tn->nametbl_lock) <<grab nametbl_lock again>> CPU1: CPU2: ---------- ---------------- tipc_nametbl_stop spin_lock_bh(&tn->nametbl_lock) tipc_purge_publications tipc_nameseq_remove_publ tipc_subscrp_report_overlap tipc_subscrp_get tipc_subscrp_send_event tipc_close_conn tipc_subscrb_release_cb tipc_subscrb_delete tipc_subscrp_put tipc_subscrp_put tipc_subscrp_kref_release tipc_nametbl_unsubscribe spin_lock_bh(&tn->nametbl_lock) <<grab nametbl_lock again>> In this commit, we advance the calling of tipc_nametbl_unsubscribe() from the refcount cleanup to the intended callers. Fixes: d094c4d5f5c7 ("tipc: add subscription refcount to avoid invalid delete") Reported-by: John Thompson <thompa.atl@gmail.com> Acked-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-21 16:47:49 +07:00
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;
tipc: remove subscription references only for pending timers In commit, 139bb36f754a ("tipc: advance the time of deleting subscription from subscriber->subscrp_list"), we delete the subscription from the subscribers list and from nametable unconditionally. This leads to the following bug if the timer running tipc_subscrp_timeout() in another CPU accesses the subscription list after the subscription delete request. [39.570] general protection fault: 0000 [#1] SMP :: [39.574] task: ffffffff81c10540 task.stack: ffffffff81c00000 [39.575] RIP: 0010:tipc_subscrp_timeout+0x32/0x80 [tipc] [39.576] RSP: 0018:ffff88003ba03e90 EFLAGS: 00010282 [39.576] RAX: dead000000000200 RBX: ffff88003f0f3600 RCX: 0000000000000101 [39.577] RDX: dead000000000100 RSI: 0000000000000201 RDI: ffff88003f0d7948 [39.578] RBP: ffff88003ba03ea0 R08: 0000000000000001 R09: ffff88003ba03ef8 [39.579] R10: 000000000000014f R11: 0000000000000000 R12: ffff88003f0d7948 [39.580] R13: ffff88003f0f3618 R14: ffffffffa006c250 R15: ffff88003f0f3600 [39.581] FS: 0000000000000000(0000) GS:ffff88003ba00000(0000) knlGS:0000000000000000 [39.582] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [39.583] CR2: 00007f831c6e0714 CR3: 000000003d3b0000 CR4: 00000000000006f0 [39.584] Call Trace: [39.584] <IRQ> [39.585] call_timer_fn+0x3d/0x180 [39.585] ? tipc_subscrb_rcv_cb+0x260/0x260 [tipc] [39.586] run_timer_softirq+0x168/0x1f0 [39.586] ? sched_clock_cpu+0x16/0xc0 [39.587] __do_softirq+0x9b/0x2de [39.587] irq_exit+0x60/0x70 [39.588] smp_apic_timer_interrupt+0x3d/0x50 [39.588] apic_timer_interrupt+0x86/0x90 [39.589] RIP: 0010:default_idle+0x20/0xf0 [39.589] RSP: 0018:ffffffff81c03e58 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 [39.590] RAX: 0000000000000000 RBX: ffffffff81c10540 RCX: 0000000000000000 [39.591] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [39.592] RBP: ffffffff81c03e68 R08: 0000000000000000 R09: 0000000000000000 [39.593] R10: ffffc90001cbbe00 R11: 0000000000000000 R12: 0000000000000000 [39.594] R13: ffffffff81c10540 R14: 0000000000000000 R15: 0000000000000000 [39.595] </IRQ> :: [39.603] RIP: tipc_subscrp_timeout+0x32/0x80 [tipc] RSP: ffff88003ba03e90 [39.604] ---[ end trace 79ce94b7216cb459 ]--- Fixes: 139bb36f754a ("tipc: advance the time of deleting subscription from subscriber->subscrp_list") Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-22 17:28:40 +07:00
u32 timeout;
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: remove subscription references only for pending timers In commit, 139bb36f754a ("tipc: advance the time of deleting subscription from subscriber->subscrp_list"), we delete the subscription from the subscribers list and from nametable unconditionally. This leads to the following bug if the timer running tipc_subscrp_timeout() in another CPU accesses the subscription list after the subscription delete request. [39.570] general protection fault: 0000 [#1] SMP :: [39.574] task: ffffffff81c10540 task.stack: ffffffff81c00000 [39.575] RIP: 0010:tipc_subscrp_timeout+0x32/0x80 [tipc] [39.576] RSP: 0018:ffff88003ba03e90 EFLAGS: 00010282 [39.576] RAX: dead000000000200 RBX: ffff88003f0f3600 RCX: 0000000000000101 [39.577] RDX: dead000000000100 RSI: 0000000000000201 RDI: ffff88003f0d7948 [39.578] RBP: ffff88003ba03ea0 R08: 0000000000000001 R09: ffff88003ba03ef8 [39.579] R10: 000000000000014f R11: 0000000000000000 R12: ffff88003f0d7948 [39.580] R13: ffff88003f0f3618 R14: ffffffffa006c250 R15: ffff88003f0f3600 [39.581] FS: 0000000000000000(0000) GS:ffff88003ba00000(0000) knlGS:0000000000000000 [39.582] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [39.583] CR2: 00007f831c6e0714 CR3: 000000003d3b0000 CR4: 00000000000006f0 [39.584] Call Trace: [39.584] <IRQ> [39.585] call_timer_fn+0x3d/0x180 [39.585] ? tipc_subscrb_rcv_cb+0x260/0x260 [tipc] [39.586] run_timer_softirq+0x168/0x1f0 [39.586] ? sched_clock_cpu+0x16/0xc0 [39.587] __do_softirq+0x9b/0x2de [39.587] irq_exit+0x60/0x70 [39.588] smp_apic_timer_interrupt+0x3d/0x50 [39.588] apic_timer_interrupt+0x86/0x90 [39.589] RIP: 0010:default_idle+0x20/0xf0 [39.589] RSP: 0018:ffffffff81c03e58 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 [39.590] RAX: 0000000000000000 RBX: ffffffff81c10540 RCX: 0000000000000000 [39.591] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [39.592] RBP: ffffffff81c03e68 R08: 0000000000000000 R09: 0000000000000000 [39.593] R10: ffffc90001cbbe00 R11: 0000000000000000 R12: 0000000000000000 [39.594] R13: ffffffff81c10540 R14: 0000000000000000 R15: 0000000000000000 [39.595] </IRQ> :: [39.603] RIP: tipc_subscrp_timeout+0x32/0x80 [tipc] RSP: ffff88003ba03e90 [39.604] ---[ end trace 79ce94b7216cb459 ]--- Fixes: 139bb36f754a ("tipc: advance the time of deleting subscription from subscriber->subscrp_list") Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-22 17:28:40 +07:00
timeout = htohl(sub->evt.s.timeout, sub->swap);
if (timeout == TIPC_WAIT_FOREVER || del_timer(&sub->timer)) {
tipc_nametbl_unsubscribe(sub);
list_del(&sub->subscrp_list);
tipc_subscrp_put(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: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
{
tipc_subscrb_subscrp_delete(subscriber, NULL);
tipc_subscrb_put(subscriber);
}
static void tipc_subscrp_cancel(struct tipc_subscr *s,
struct tipc_subscriber *subscriber)
{
tipc: fix a race condition of releasing subscriber object No matter whether a request is inserted into workqueue as a work item to cancel a subscription or to delete a subscription's subscriber asynchronously, the work items may be executed in different workers. As a result, it doesn't mean that one request which is raised prior to another request is definitely handled before the latter. By contrast, if the latter request is executed before the former request, below error may happen: [ 656.183644] BUG: spinlock bad magic on CPU#0, kworker/u8:0/12117 [ 656.184487] general protection fault: 0000 [#1] SMP [ 656.185160] Modules linked in: tipc ip6_udp_tunnel udp_tunnel 9pnet_virtio 9p 9pnet virtio_net virtio_pci virtio_ring virtio [last unloaded: ip6_udp_tunnel] [ 656.187003] CPU: 0 PID: 12117 Comm: kworker/u8:0 Not tainted 4.11.0-rc7+ #6 [ 656.187920] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 656.188690] Workqueue: tipc_rcv tipc_recv_work [tipc] [ 656.189371] task: ffff88003f5cec40 task.stack: ffffc90004448000 [ 656.190157] RIP: 0010:spin_bug+0xdd/0xf0 [ 656.190678] RSP: 0018:ffffc9000444bcb8 EFLAGS: 00010202 [ 656.191375] RAX: 0000000000000034 RBX: ffff88003f8d1388 RCX: 0000000000000000 [ 656.192321] RDX: ffff88003ba13708 RSI: ffff88003ba0cd08 RDI: ffff88003ba0cd08 [ 656.193265] RBP: ffffc9000444bcd0 R08: 0000000000000030 R09: 000000006b6b6b6b [ 656.194208] R10: ffff8800bde3e000 R11: 00000000000001b4 R12: 6b6b6b6b6b6b6b6b [ 656.195157] R13: ffffffff81a3ca64 R14: ffff88003f8d1388 R15: ffff88003f8d13a0 [ 656.196101] FS: 0000000000000000(0000) GS:ffff88003ba00000(0000) knlGS:0000000000000000 [ 656.197172] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 656.197935] CR2: 00007f0b3d2e6000 CR3: 000000003ef9e000 CR4: 00000000000006f0 [ 656.198873] Call Trace: [ 656.199210] do_raw_spin_lock+0x66/0xa0 [ 656.199735] _raw_spin_lock_bh+0x19/0x20 [ 656.200258] tipc_subscrb_subscrp_delete+0x28/0xf0 [tipc] [ 656.200990] tipc_subscrb_rcv_cb+0x45/0x260 [tipc] [ 656.201632] tipc_receive_from_sock+0xaf/0x100 [tipc] [ 656.202299] tipc_recv_work+0x2b/0x60 [tipc] [ 656.202872] process_one_work+0x157/0x420 [ 656.203404] worker_thread+0x69/0x4c0 [ 656.203898] kthread+0x138/0x170 [ 656.204328] ? process_one_work+0x420/0x420 [ 656.204889] ? kthread_create_on_node+0x40/0x40 [ 656.205527] ret_from_fork+0x29/0x40 [ 656.206012] Code: 48 8b 0c 25 00 c5 00 00 48 c7 c7 f0 24 a3 81 48 81 c1 f0 05 00 00 65 8b 15 61 ef f5 7e e8 9a 4c 09 00 4d 85 e4 44 8b 4b 08 74 92 <45> 8b 84 24 40 04 00 00 49 8d 8c 24 f0 05 00 00 eb 8d 90 0f 1f [ 656.208504] RIP: spin_bug+0xdd/0xf0 RSP: ffffc9000444bcb8 [ 656.209798] ---[ end trace e2a800e6eb0770be ]--- In above scenario, the request of deleting subscriber was performed earlier than the request of canceling a subscription although the latter was issued before the former, which means tipc_subscrb_delete() was called before tipc_subscrp_cancel(). As a result, when tipc_subscrb_subscrp_delete() called by tipc_subscrp_cancel() was executed to cancel a subscription, the subscription's subscriber refcnt had been decreased to 1. After tipc_subscrp_delete() where the subscriber was freed because its refcnt was decremented to zero, but the subscriber's lock had to be released, as a consequence, panic happened. By contrast, if we increase subscriber's refcnt before tipc_subscrb_subscrp_delete() is called in tipc_subscrp_cancel(), the panic issue can be avoided. Fixes: d094c4d5f5c7 ("tipc: add subscription refcount to avoid invalid delete") Reported-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-22 17:28:41 +07:00
tipc_subscrb_get(subscriber);
tipc_subscrb_subscrp_delete(subscriber, s);
tipc: fix a race condition of releasing subscriber object No matter whether a request is inserted into workqueue as a work item to cancel a subscription or to delete a subscription's subscriber asynchronously, the work items may be executed in different workers. As a result, it doesn't mean that one request which is raised prior to another request is definitely handled before the latter. By contrast, if the latter request is executed before the former request, below error may happen: [ 656.183644] BUG: spinlock bad magic on CPU#0, kworker/u8:0/12117 [ 656.184487] general protection fault: 0000 [#1] SMP [ 656.185160] Modules linked in: tipc ip6_udp_tunnel udp_tunnel 9pnet_virtio 9p 9pnet virtio_net virtio_pci virtio_ring virtio [last unloaded: ip6_udp_tunnel] [ 656.187003] CPU: 0 PID: 12117 Comm: kworker/u8:0 Not tainted 4.11.0-rc7+ #6 [ 656.187920] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 656.188690] Workqueue: tipc_rcv tipc_recv_work [tipc] [ 656.189371] task: ffff88003f5cec40 task.stack: ffffc90004448000 [ 656.190157] RIP: 0010:spin_bug+0xdd/0xf0 [ 656.190678] RSP: 0018:ffffc9000444bcb8 EFLAGS: 00010202 [ 656.191375] RAX: 0000000000000034 RBX: ffff88003f8d1388 RCX: 0000000000000000 [ 656.192321] RDX: ffff88003ba13708 RSI: ffff88003ba0cd08 RDI: ffff88003ba0cd08 [ 656.193265] RBP: ffffc9000444bcd0 R08: 0000000000000030 R09: 000000006b6b6b6b [ 656.194208] R10: ffff8800bde3e000 R11: 00000000000001b4 R12: 6b6b6b6b6b6b6b6b [ 656.195157] R13: ffffffff81a3ca64 R14: ffff88003f8d1388 R15: ffff88003f8d13a0 [ 656.196101] FS: 0000000000000000(0000) GS:ffff88003ba00000(0000) knlGS:0000000000000000 [ 656.197172] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 656.197935] CR2: 00007f0b3d2e6000 CR3: 000000003ef9e000 CR4: 00000000000006f0 [ 656.198873] Call Trace: [ 656.199210] do_raw_spin_lock+0x66/0xa0 [ 656.199735] _raw_spin_lock_bh+0x19/0x20 [ 656.200258] tipc_subscrb_subscrp_delete+0x28/0xf0 [tipc] [ 656.200990] tipc_subscrb_rcv_cb+0x45/0x260 [tipc] [ 656.201632] tipc_receive_from_sock+0xaf/0x100 [tipc] [ 656.202299] tipc_recv_work+0x2b/0x60 [tipc] [ 656.202872] process_one_work+0x157/0x420 [ 656.203404] worker_thread+0x69/0x4c0 [ 656.203898] kthread+0x138/0x170 [ 656.204328] ? process_one_work+0x420/0x420 [ 656.204889] ? kthread_create_on_node+0x40/0x40 [ 656.205527] ret_from_fork+0x29/0x40 [ 656.206012] Code: 48 8b 0c 25 00 c5 00 00 48 c7 c7 f0 24 a3 81 48 81 c1 f0 05 00 00 65 8b 15 61 ef f5 7e e8 9a 4c 09 00 4d 85 e4 44 8b 4b 08 74 92 <45> 8b 84 24 40 04 00 00 49 8d 8c 24 f0 05 00 00 eb 8d 90 0f 1f [ 656.208504] RIP: spin_bug+0xdd/0xf0 RSP: ffffc9000444bcb8 [ 656.209798] ---[ end trace e2a800e6eb0770be ]--- In above scenario, the request of deleting subscriber was performed earlier than the request of canceling a subscription although the latter was issued before the former, which means tipc_subscrb_delete() was called before tipc_subscrp_cancel(). As a result, when tipc_subscrb_subscrp_delete() called by tipc_subscrp_cancel() was executed to cancel a subscription, the subscription's subscriber refcnt had been decreased to 1. After tipc_subscrp_delete() where the subscriber was freed because its refcnt was decremented to zero, but the subscriber's lock had to be released, as a consequence, panic happened. By contrast, if we increase subscriber's refcnt before tipc_subscrb_subscrp_delete() is called in tipc_subscrp_cancel(), the panic issue can be avoided. Fixes: d094c4d5f5c7 ("tipc: add subscription refcount to avoid invalid delete") Reported-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-22 17:28:41 +07:00
tipc_subscrb_put(subscriber);
}
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;
}
tipc: fix race condition at topology server receive We have identified a race condition during reception of socket events and messages in the topology server. - The function tipc_close_conn() is releasing the corresponding struct tipc_subscriber instance without considering that there may still be items in the receive work queue. When those are scheduled, in the function tipc_receive_from_work(), they are using the subscriber pointer stored in struct tipc_conn, without first checking if this is valid or not. This will sometimes lead to crashes, as the next call of tipc_conn_recvmsg() will access the now deleted item. We fix this by making the usage of this pointer conditional on whether the connection is active or not. I.e., we check the condition test_bit(CF_CONNECTED) before making the call tipc_conn_recvmsg(). - Since the two functions may be running on different cores, the condition test described above is not enough. tipc_close_conn() may come in between and delete the subscriber item after the condition test is done, but before tipc_conn_recv_msg() is finished. This happens less frequently than the problem described above, but leads to the same symptoms. We fix this by using the existing sk_callback_lock for mutual exclusion in the two functions. In addition, we have to move a call to tipc_conn_terminate() outside the mentioned lock to avoid deadlock. Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-01-15 23:56:28 +07:00
static int tipc_subscrp_subscribe(struct net *net, struct tipc_subscr *s,
struct tipc_subscriber *subscriber, int swap,
bool status)
{
struct tipc_subscription *sub = NULL;
u32 timeout;
sub = tipc_subscrp_create(net, s, swap);
if (!sub)
tipc: fix race condition at topology server receive We have identified a race condition during reception of socket events and messages in the topology server. - The function tipc_close_conn() is releasing the corresponding struct tipc_subscriber instance without considering that there may still be items in the receive work queue. When those are scheduled, in the function tipc_receive_from_work(), they are using the subscriber pointer stored in struct tipc_conn, without first checking if this is valid or not. This will sometimes lead to crashes, as the next call of tipc_conn_recvmsg() will access the now deleted item. We fix this by making the usage of this pointer conditional on whether the connection is active or not. I.e., we check the condition test_bit(CF_CONNECTED) before making the call tipc_conn_recvmsg(). - Since the two functions may be running on different cores, the condition test described above is not enough. tipc_close_conn() may come in between and delete the subscriber item after the condition test is done, but before tipc_conn_recv_msg() is finished. This happens less frequently than the problem described above, but leads to the same symptoms. We fix this by using the existing sk_callback_lock for mutual exclusion in the two functions. In addition, we have to move a call to tipc_conn_terminate() outside the mentioned lock to avoid deadlock. Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-01-15 23:56:28 +07:00
return -1;
spin_lock_bh(&subscriber->lock);
list_add(&sub->subscrp_list, &subscriber->subscrp_list);
tipc: hold subscriber->lock for tipc_nametbl_subscribe() Until now, while creating a subscription the subscriber lock protects only the subscribers subscription list and not the nametable. The call to tipc_nametbl_subscribe() is outside the lock. However, at subscription timeout and cancel both the subscribers subscription list and the nametable are protected by the subscriber lock. This asymmetric locking mechanism leads to the following problem: In a SMP system, the timer can be fire on another core before the create request is complete. When the timer thread calls tipc_nametbl_unsubscribe() before create thread calls tipc_nametbl_subscribe(), we get a nullptr exception. This can be simulated by creating subscription with timeout=0 and sometimes the timeout occurs before the create request is complete. The following is the oops: [57.569661] BUG: unable to handle kernel NULL pointer dereference at (null) [57.577498] IP: [<ffffffffa02135aa>] tipc_nametbl_unsubscribe+0x8a/0x120 [tipc] [57.584820] PGD 0 [57.586834] Oops: 0002 [#1] SMP [57.685506] CPU: 14 PID: 10077 Comm: kworker/u40:1 Tainted: P OENX 3.12.48-52.27.1. 9688.1.PTF-default #1 [57.703637] Workqueue: tipc_rcv tipc_recv_work [tipc] [57.708697] task: ffff88064c7f00c0 ti: ffff880629ef4000 task.ti: ffff880629ef4000 [57.716181] RIP: 0010:[<ffffffffa02135aa>] [<ffffffffa02135aa>] tipc_nametbl_unsubscribe+0x8a/ 0x120 [tipc] [...] [57.812327] Call Trace: [57.814806] [<ffffffffa0211c77>] tipc_subscrp_delete+0x37/0x90 [tipc] [57.821357] [<ffffffffa0211e2f>] tipc_subscrp_timeout+0x3f/0x70 [tipc] [57.827982] [<ffffffff810618c1>] call_timer_fn+0x31/0x100 [57.833490] [<ffffffff81062709>] run_timer_softirq+0x1f9/0x2b0 [57.839414] [<ffffffff8105a795>] __do_softirq+0xe5/0x230 [57.844827] [<ffffffff81520d1c>] call_softirq+0x1c/0x30 [57.850150] [<ffffffff81004665>] do_softirq+0x55/0x90 [57.855285] [<ffffffff8105aa35>] irq_exit+0x95/0xa0 [57.860290] [<ffffffff815215b5>] smp_apic_timer_interrupt+0x45/0x60 [57.866644] [<ffffffff8152005d>] apic_timer_interrupt+0x6d/0x80 [57.872686] [<ffffffffa02121c5>] tipc_subscrb_rcv_cb+0x2a5/0x3f0 [tipc] [57.879425] [<ffffffffa021c65f>] tipc_receive_from_sock+0x9f/0x100 [tipc] [57.886324] [<ffffffffa021c826>] tipc_recv_work+0x26/0x60 [tipc] [57.892463] [<ffffffff8106fb22>] process_one_work+0x172/0x420 [57.898309] [<ffffffff8107079a>] worker_thread+0x11a/0x3c0 [57.903871] [<ffffffff81077114>] kthread+0xb4/0xc0 [57.908751] [<ffffffff8151f318>] ret_from_fork+0x58/0x90 In this commit, we do the following at subscription creation: 1. set the subscription's subscriber pointer before performing tipc_nametbl_subscribe(), as this value is required further in the call chain ex: by tipc_subscrp_send_event(). 2. move tipc_nametbl_subscribe() under the scope of subscriber lock Acked-by: Ying Xue <ying.xue@windriver.com> Reviewed-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-02-02 16:52:14 +07:00
sub->subscriber = subscriber;
tipc_nametbl_subscribe(sub, status);
tipc_subscrb_get(subscriber);
spin_unlock_bh(&subscriber->lock);
timer_setup(&sub->timer, tipc_subscrp_timeout, 0);
timeout = htohl(sub->evt.s.timeout, swap);
if (timeout != TIPC_WAIT_FOREVER)
mod_timer(&sub->timer, jiffies + msecs_to_jiffies(timeout));
tipc: fix race condition at topology server receive We have identified a race condition during reception of socket events and messages in the topology server. - The function tipc_close_conn() is releasing the corresponding struct tipc_subscriber instance without considering that there may still be items in the receive work queue. When those are scheduled, in the function tipc_receive_from_work(), they are using the subscriber pointer stored in struct tipc_conn, without first checking if this is valid or not. This will sometimes lead to crashes, as the next call of tipc_conn_recvmsg() will access the now deleted item. We fix this by making the usage of this pointer conditional on whether the connection is active or not. I.e., we check the condition test_bit(CF_CONNECTED) before making the call tipc_conn_recvmsg(). - Since the two functions may be running on different cores, the condition test described above is not enough. tipc_close_conn() may come in between and delete the subscriber item after the condition test is done, but before tipc_conn_recv_msg() is finished. This happens less frequently than the problem described above, but leads to the same symptoms. We fix this by using the existing sk_callback_lock for mutual exclusion in the two functions. In addition, we have to move a call to tipc_conn_terminate() outside the mentioned lock to avoid deadlock. Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-01-15 23:56:28 +07:00
return 0;
}
tipc: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
/* Handle one termination request for the subscriber */
tipc: fix a race condition leading to subscriber refcnt bug Until now, the requests sent to topology server are queued to a workqueue by the generic server framework. These messages are processed by worker threads and trigger the registered callbacks. To reduce latency on uniprocessor systems, explicit rescheduling is performed using cond_resched() after MAX_RECV_MSG_COUNT(25) messages. This implementation on SMP systems leads to an subscriber refcnt error as described below: When a worker thread yields by calling cond_resched() in a SMP system, a new worker is created on another CPU to process the pending workitem. Sometimes the sleeping thread wakes up before the new thread finishes execution. This breaks the assumption on ordering and being single threaded. The fault is more frequent when MAX_RECV_MSG_COUNT is lowered. If the first thread was processing subscription create and the second thread processing close(), the close request will free the subscriber and the create request oops as follows: [31.224137] WARNING: CPU: 2 PID: 266 at include/linux/kref.h:46 tipc_subscrb_rcv_cb+0x317/0x380 [tipc] [31.228143] CPU: 2 PID: 266 Comm: kworker/u8:1 Not tainted 4.5.0+ #97 [31.228377] Workqueue: tipc_rcv tipc_recv_work [tipc] [...] [31.228377] Call Trace: [31.228377] [<ffffffff812fbb6b>] dump_stack+0x4d/0x72 [31.228377] [<ffffffff8105a311>] __warn+0xd1/0xf0 [31.228377] [<ffffffff8105a3fd>] warn_slowpath_null+0x1d/0x20 [31.228377] [<ffffffffa0098067>] tipc_subscrb_rcv_cb+0x317/0x380 [tipc] [31.228377] [<ffffffffa00a4984>] tipc_receive_from_sock+0xd4/0x130 [tipc] [31.228377] [<ffffffffa00a439b>] tipc_recv_work+0x2b/0x50 [tipc] [31.228377] [<ffffffff81071925>] process_one_work+0x145/0x3d0 [31.246554] ---[ end trace c3882c9baa05a4fd ]--- [31.248327] BUG: spinlock bad magic on CPU#2, kworker/u8:1/266 [31.249119] BUG: unable to handle kernel NULL pointer dereference at 0000000000000428 [31.249323] IP: [<ffffffff81099d0c>] spin_dump+0x5c/0xe0 [31.249323] PGD 0 [31.249323] Oops: 0000 [#1] SMP In this commit, we - rename tipc_conn_shutdown() to tipc_conn_release(). - move connection release callback execution from tipc_close_conn() to a new function tipc_sock_release(), which is executed before we free the connection. Thus we release the subscriber during connection release procedure rather than connection shutdown procedure. Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-12 18:05:21 +07:00
static void tipc_subscrb_release_cb(int conid, void *usr_data)
{
tipc_subscrb_delete((struct tipc_subscriber *)usr_data);
}
tipc: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
/* Handle one request to create a new subscription for the subscriber */
tipc: fix race condition at topology server receive We have identified a race condition during reception of socket events and messages in the topology server. - The function tipc_close_conn() is releasing the corresponding struct tipc_subscriber instance without considering that there may still be items in the receive work queue. When those are scheduled, in the function tipc_receive_from_work(), they are using the subscriber pointer stored in struct tipc_conn, without first checking if this is valid or not. This will sometimes lead to crashes, as the next call of tipc_conn_recvmsg() will access the now deleted item. We fix this by making the usage of this pointer conditional on whether the connection is active or not. I.e., we check the condition test_bit(CF_CONNECTED) before making the call tipc_conn_recvmsg(). - Since the two functions may be running on different cores, the condition test described above is not enough. tipc_close_conn() may come in between and delete the subscriber item after the condition test is done, but before tipc_conn_recv_msg() is finished. This happens less frequently than the problem described above, but leads to the same symptoms. We fix this by using the existing sk_callback_lock for mutual exclusion in the two functions. In addition, we have to move a call to tipc_conn_terminate() outside the mentioned lock to avoid deadlock. Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-01-15 23:56:28 +07:00
static int 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;
bool status;
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);
tipc: fix race condition at topology server receive We have identified a race condition during reception of socket events and messages in the topology server. - The function tipc_close_conn() is releasing the corresponding struct tipc_subscriber instance without considering that there may still be items in the receive work queue. When those are scheduled, in the function tipc_receive_from_work(), they are using the subscriber pointer stored in struct tipc_conn, without first checking if this is valid or not. This will sometimes lead to crashes, as the next call of tipc_conn_recvmsg() will access the now deleted item. We fix this by making the usage of this pointer conditional on whether the connection is active or not. I.e., we check the condition test_bit(CF_CONNECTED) before making the call tipc_conn_recvmsg(). - Since the two functions may be running on different cores, the condition test described above is not enough. tipc_close_conn() may come in between and delete the subscriber item after the condition test is done, but before tipc_conn_recv_msg() is finished. This happens less frequently than the problem described above, but leads to the same symptoms. We fix this by using the existing sk_callback_lock for mutual exclusion in the two functions. In addition, we have to move a call to tipc_conn_terminate() outside the mentioned lock to avoid deadlock. Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-01-15 23:56:28 +07:00
tipc_subscrp_cancel(s, subscriber);
return 0;
}
status = !(s->filter & htohl(TIPC_SUB_NO_STATUS, swap));
tipc: fix race condition at topology server receive We have identified a race condition during reception of socket events and messages in the topology server. - The function tipc_close_conn() is releasing the corresponding struct tipc_subscriber instance without considering that there may still be items in the receive work queue. When those are scheduled, in the function tipc_receive_from_work(), they are using the subscriber pointer stored in struct tipc_conn, without first checking if this is valid or not. This will sometimes lead to crashes, as the next call of tipc_conn_recvmsg() will access the now deleted item. We fix this by making the usage of this pointer conditional on whether the connection is active or not. I.e., we check the condition test_bit(CF_CONNECTED) before making the call tipc_conn_recvmsg(). - Since the two functions may be running on different cores, the condition test described above is not enough. tipc_close_conn() may come in between and delete the subscriber item after the condition test is done, but before tipc_conn_recv_msg() is finished. This happens less frequently than the problem described above, but leads to the same symptoms. We fix this by using the existing sk_callback_lock for mutual exclusion in the two functions. In addition, we have to move a call to tipc_conn_terminate() outside the mentioned lock to avoid deadlock. Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-01-15 23:56:28 +07:00
return tipc_subscrp_subscribe(net, s, subscriber, swap, status);
}
tipc: convert topology server to use new server facility As the new TIPC server infrastructure has been introduced, we can now convert the TIPC topology server to it. We get two benefits from doing this: 1) It simplifies the topology server locking policy. In the original locking policy, we placed one spin lock pointer in the tipc_subscriber structure to reuse the lock of the subscriber's server port, controlling access to members of tipc_subscriber instance. That is, we only used one lock to ensure both tipc_port and tipc_subscriber members were safely accessed. Now we introduce another spin lock for tipc_subscriber structure only protecting themselves, to get a finer granularity locking policy. Moreover, the change will allow us to make the topology server code more readable and maintainable. 2) It fixes a bug where sent subscription events may be lost when the topology port is congested. Using the new service, the topology server now queues sent events into an outgoing buffer, and then wakes up a sender process which has been blocked in workqueue context. The process will keep picking events from the buffer and send them to their respective subscribers, using the kernel socket interface, until the buffer is empty. Even if the socket is congested during transmission there is no risk that events may be dropped, since the sender process may block when needed. Some minor reordering of initialization is done, since we now have a scenario where the topology server must be started after socket initialization has taken place, as the former depends on the latter. And overall, we see a simplification of the TIPC subscriber code in making this changeover. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-06-17 21:54:40 +07:00
/* 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;
tipc: fix a race condition leading to subscriber refcnt bug Until now, the requests sent to topology server are queued to a workqueue by the generic server framework. These messages are processed by worker threads and trigger the registered callbacks. To reduce latency on uniprocessor systems, explicit rescheduling is performed using cond_resched() after MAX_RECV_MSG_COUNT(25) messages. This implementation on SMP systems leads to an subscriber refcnt error as described below: When a worker thread yields by calling cond_resched() in a SMP system, a new worker is created on another CPU to process the pending workitem. Sometimes the sleeping thread wakes up before the new thread finishes execution. This breaks the assumption on ordering and being single threaded. The fault is more frequent when MAX_RECV_MSG_COUNT is lowered. If the first thread was processing subscription create and the second thread processing close(), the close request will free the subscriber and the create request oops as follows: [31.224137] WARNING: CPU: 2 PID: 266 at include/linux/kref.h:46 tipc_subscrb_rcv_cb+0x317/0x380 [tipc] [31.228143] CPU: 2 PID: 266 Comm: kworker/u8:1 Not tainted 4.5.0+ #97 [31.228377] Workqueue: tipc_rcv tipc_recv_work [tipc] [...] [31.228377] Call Trace: [31.228377] [<ffffffff812fbb6b>] dump_stack+0x4d/0x72 [31.228377] [<ffffffff8105a311>] __warn+0xd1/0xf0 [31.228377] [<ffffffff8105a3fd>] warn_slowpath_null+0x1d/0x20 [31.228377] [<ffffffffa0098067>] tipc_subscrb_rcv_cb+0x317/0x380 [tipc] [31.228377] [<ffffffffa00a4984>] tipc_receive_from_sock+0xd4/0x130 [tipc] [31.228377] [<ffffffffa00a439b>] tipc_recv_work+0x2b/0x50 [tipc] [31.228377] [<ffffffff81071925>] process_one_work+0x145/0x3d0 [31.246554] ---[ end trace c3882c9baa05a4fd ]--- [31.248327] BUG: spinlock bad magic on CPU#2, kworker/u8:1/266 [31.249119] BUG: unable to handle kernel NULL pointer dereference at 0000000000000428 [31.249323] IP: [<ffffffff81099d0c>] spin_dump+0x5c/0xe0 [31.249323] PGD 0 [31.249323] Oops: 0000 [#1] SMP In this commit, we - rename tipc_conn_shutdown() to tipc_conn_release(). - move connection release callback execution from tipc_close_conn() to a new function tipc_sock_release(), which is executed before we free the connection. Thus we release the subscriber during connection release procedure rather than connection shutdown procedure. Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com> Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-04-12 18:05:21 +07:00
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);
}