linux/net/tipc
Kolmakov Dmitriy 7845989cb4 net: tipc: fix stall during bclink wakeup procedure
If an attempt to wake up users of broadcast link is made when there is
no enough place in send queue than it may hang up inside the
tipc_sk_rcv() function since the loop breaks only after the wake up
queue becomes empty. This can lead to complete CPU stall with the
following message generated by RCU:

INFO: rcu_sched self-detected stall on CPU { 0}  (t=2101 jiffies
					g=54225 c=54224 q=11465)
Task dump for CPU 0:
tpch            R  running task        0 39949  39948 0x0000000a
 ffffffff818536c0 ffff88181fa037a0 ffffffff8106a4be 0000000000000000
 ffffffff818536c0 ffff88181fa037c0 ffffffff8106d8a8 ffff88181fa03800
 0000000000000001 ffff88181fa037f0 ffffffff81094a50 ffff88181fa15680
Call Trace:
 <IRQ>  [<ffffffff8106a4be>] sched_show_task+0xae/0x120
 [<ffffffff8106d8a8>] dump_cpu_task+0x38/0x40
 [<ffffffff81094a50>] rcu_dump_cpu_stacks+0x90/0xd0
 [<ffffffff81097c3b>] rcu_check_callbacks+0x3eb/0x6e0
 [<ffffffff8106e53f>] ? account_system_time+0x7f/0x170
 [<ffffffff81099e64>] update_process_times+0x34/0x60
 [<ffffffff810a84d1>] tick_sched_handle.isra.18+0x31/0x40
 [<ffffffff810a851c>] tick_sched_timer+0x3c/0x70
 [<ffffffff8109a43d>] __run_hrtimer.isra.34+0x3d/0xc0
 [<ffffffff8109aa95>] hrtimer_interrupt+0xc5/0x1e0
 [<ffffffff81030d52>] ? native_smp_send_reschedule+0x42/0x60
 [<ffffffff81032f04>] local_apic_timer_interrupt+0x34/0x60
 [<ffffffff810335bc>] smp_apic_timer_interrupt+0x3c/0x60
 [<ffffffff8165a3fb>] apic_timer_interrupt+0x6b/0x70
 [<ffffffff81659129>] ? _raw_spin_unlock_irqrestore+0x9/0x10
 [<ffffffff8107eb9f>] __wake_up_sync_key+0x4f/0x60
 [<ffffffffa313ddd1>] tipc_write_space+0x31/0x40 [tipc]
 [<ffffffffa313dadf>] filter_rcv+0x31f/0x520 [tipc]
 [<ffffffffa313d699>] ? tipc_sk_lookup+0xc9/0x110 [tipc]
 [<ffffffff81659259>] ? _raw_spin_lock_bh+0x19/0x30
 [<ffffffffa314122c>] tipc_sk_rcv+0x2dc/0x3e0 [tipc]
 [<ffffffffa312e7ff>] tipc_bclink_wakeup_users+0x2f/0x40 [tipc]
 [<ffffffffa313ce26>] tipc_node_unlock+0x186/0x190 [tipc]
 [<ffffffff81597c1c>] ? kfree_skb+0x2c/0x40
 [<ffffffffa313475c>] tipc_rcv+0x2ac/0x8c0 [tipc]
 [<ffffffffa312ff58>] tipc_l2_rcv_msg+0x38/0x50 [tipc]
 [<ffffffff815a76d3>] __netif_receive_skb_core+0x5a3/0x950
 [<ffffffff815a98d3>] __netif_receive_skb+0x13/0x60
 [<ffffffff815a993e>] netif_receive_skb_internal+0x1e/0x90
 [<ffffffff815aa138>] napi_gro_receive+0x78/0xa0
 [<ffffffffa07f93f4>] tg3_poll_work+0xc54/0xf40 [tg3]
 [<ffffffff81597c8c>] ? consume_skb+0x2c/0x40
 [<ffffffffa07f9721>] tg3_poll_msix+0x41/0x160 [tg3]
 [<ffffffff815ab0f2>] net_rx_action+0xe2/0x290
 [<ffffffff8104b92a>] __do_softirq+0xda/0x1f0
 [<ffffffff8104bc26>] irq_exit+0x76/0xa0
 [<ffffffff81004355>] do_IRQ+0x55/0xf0
 [<ffffffff8165a12b>] common_interrupt+0x6b/0x6b
 <EOI>

The issue occurs only when tipc_sk_rcv() is used to wake up postponed
senders:

	tipc_bclink_wakeup_users()
		// wakeupq - is a queue which consists of special
		// 		 messages with SOCK_WAKEUP type.
		tipc_sk_rcv(wakeupq)
			...
			while (skb_queue_len(inputq)) {
				filter_rcv(skb)
					// Here the type of message is checked
					// and if it is SOCK_WAKEUP then
					// it tries to wake up a sender.
					tipc_write_space(sk)
						wake_up_interruptible_sync_poll()
			}

After the sender thread is woke up it can gather control and perform
an attempt to send a message. But if there is no enough place in send
queue it will call link_schedule_user() function which puts a message
of type SOCK_WAKEUP to the wakeup queue and put the sender to sleep.
Thus the size of the queue actually is not changed and the while()
loop never exits.

The approach I proposed is to wake up only senders for which there is
enough place in send queue so the described issue can't occur.
Moreover the same approach is already used to wake up senders on
unicast links.

I have got into the issue on our product code but to reproduce the
issue I changed a benchmark test application (from
tipcutils/demos/benchmark) to perform the following scenario:
	1. Run 64 instances of test application (nodes). It can be done
	   on the one physical machine.
	2. Each application connects to all other using TIPC sockets in
	   RDM mode.
	3. When setup is done all nodes start simultaneously send
	   broadcast messages.
	4. Everything hangs up.

The issue is reproducible only when a congestion on broadcast link
occurs. For example, when there are only 8 nodes it works fine since
congestion doesn't occur. Send queue limit is 40 in my case (I use a
critical importance level) and when 64 nodes send a message at the
same moment a congestion occurs every time.

Signed-off-by: Dmitry S Kolmakov <kolmakov.dmitriy@huawei.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-08 22:50:26 -07:00
..
addr.c tipc: simplify include dependencies 2015-05-14 12:24:45 -04:00
addr.h tipc: simplify include dependencies 2015-05-14 12:24:45 -04:00
bcast.c net: tipc: fix stall during bclink wakeup procedure 2015-09-08 22:50:26 -07:00
bcast.h tipc: reduce locking scope during packet reception 2015-07-20 20:41:16 -07:00
bearer.c tipc: move all link_reset() calls to link aggregation level 2015-07-30 17:25:13 -07:00
bearer.h tipc: make media xmit call outside node spinlock context 2015-07-20 20:41:15 -07:00
core.c tipc: rename functions defined in subscr.c 2015-05-04 15:04:00 -04:00
core.h tipc: clean up link creation 2015-07-30 17:25:15 -07:00
discover.c tipc: move received discovery data evaluation inside node.c 2015-07-30 17:25:14 -07:00
discover.h tipc: involve namespace infrastructure 2015-01-12 16:24:32 -05:00
eth_media.c tipc: make media address offset a common define 2015-02-27 18:18:48 -05:00
ib_media.c tipc: rename media/msg related definitions 2015-02-27 18:18:48 -05:00
Kconfig tipc: add ip/udp media type 2015-03-05 22:08:42 -05:00
link.c tipc: fix stale link problem during synchronization 2015-08-23 16:14:45 -07:00
link.h tipc: clean up link creation 2015-07-30 17:25:15 -07:00
Makefile tipc: add ip/udp media type 2015-03-05 22:08:42 -05:00
msg.c tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
msg.h tipc: remove implicit message delivery in node_unlock() 2015-07-30 17:25:14 -07:00
name_distr.c tipc: make media xmit call outside node spinlock context 2015-07-20 20:41:15 -07:00
name_distr.h tipc: resolve race problem at unicast message reception 2015-02-05 16:00:02 -08:00
name_table.c tipc: rename functions defined in subscr.c 2015-05-04 15:04:00 -04:00
name_table.h tipc: convert legacy nl name table dump to nl compat 2015-02-09 13:20:48 -08:00
net.c tipc: simplify include dependencies 2015-05-14 12:24:45 -04:00
net.h tipc: make tipc node table aware of net namespace 2015-01-12 16:24:32 -05:00
netlink.c tipc: move and rename the legacy nl api to "nl compat" 2015-02-09 13:20:47 -08:00
netlink.h tipc: move and rename the legacy nl api to "nl compat" 2015-02-09 13:20:47 -08:00
netlink_compat.c tipc: don't sanity check non-existing TLV (NL compat) 2015-08-17 10:39:54 -07:00
node.c tipc: fix stale link problem during synchronization 2015-08-23 16:14:45 -07:00
node.h tipc: remove implicit message delivery in node_unlock() 2015-07-30 17:25:14 -07:00
server.c tipc: use sock_create_kern interface to create kernel socket 2015-05-14 13:39:33 -04:00
server.h tipc: make subscriber server support net namespace 2015-01-12 16:24:33 -05:00
socket.c tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
socket.h tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
subscr.c tipc: adjust locking policy of subscription 2015-05-04 15:04:01 -04:00
subscr.h tipc: rename functions defined in subscr.c 2015-05-04 15:04:00 -04:00
sysctl.c tipc: add name distributor resiliency queue 2014-09-01 17:51:48 -07:00
udp_media.c ipv6: change ipv6_stub_impl.ipv6_dst_lookup to take net argument 2015-07-31 15:21:30 -07:00