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f3ad288c56
linux/net/tipc
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Parthasarathy Bhuvaragan f3ad288c56 tipc: protect tipc_subscrb_get() with subscriber spin lock 
Until now, during subscription creation the mod_time() &
tipc_subscrb_get() are called after releasing the subscriber
spin lock.

In a SMP system when performing a subscription creation, if the
subscription timeout occurs simultaneously (the timer is
scheduled to run on another CPU) then the timer thread
might decrement the subscribers refcount before the create
thread increments the refcount.

This can be simulated by creating subscription with timeout=0 and
sometimes the timeout occurs before the create request is complete.
This leads to the following message:
[30.702949] BUG: spinlock bad magic on CPU#1, kworker/u8:3/87
[30.703834] general protection fault: 0000 [#1] SMP
[30.704826] CPU: 1 PID: 87 Comm: kworker/u8:3 Not tainted 4.4.0-rc8+ #18
[30.704826] Workqueue: tipc_rcv tipc_recv_work [tipc]
[30.704826] task: ffff88003f878600 ti: ffff88003fae0000 task.ti: ffff88003fae0000
[30.704826] RIP: 0010:[<ffffffff8109196c>]  [<ffffffff8109196c>] spin_dump+0x5c/0xe0
[...]
[30.704826] Call Trace:
[30.704826]  [<ffffffff81091a16>] spin_bug+0x26/0x30
[30.704826]  [<ffffffff81091b75>] do_raw_spin_lock+0xe5/0x120
[30.704826]  [<ffffffff81684439>] _raw_spin_lock_bh+0x19/0x20
[30.704826]  [<ffffffffa0096f10>] tipc_subscrb_rcv_cb+0x1d0/0x330 [tipc]
[30.704826]  [<ffffffffa00a37b1>] tipc_receive_from_sock+0xc1/0x150 [tipc]
[30.704826]  [<ffffffffa00a31df>] tipc_recv_work+0x3f/0x80 [tipc]
[30.704826]  [<ffffffff8106a739>] process_one_work+0x149/0x3c0
[30.704826]  [<ffffffff8106aa16>] worker_thread+0x66/0x460
[30.704826]  [<ffffffff8106a9b0>] ? process_one_work+0x3c0/0x3c0
[30.704826]  [<ffffffff8106a9b0>] ? process_one_work+0x3c0/0x3c0
[30.704826]  [<ffffffff8107029d>] kthread+0xed/0x110
[30.704826]  [<ffffffff810701b0>] ? kthread_create_on_node+0x190/0x190
[30.704826]  [<ffffffff81684bdf>] ret_from_fork+0x3f/0x70

In this commit,
1. we remove the check for the return code for mod_timer()
2. we protect tipc_subscrb_get() using the subscriber spin lock.
   We increment the subscriber's refcount as soon as we add the
   subscription to subscriber's subscription list.

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>
2016-02-06 03:41:58 -05:00
..
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 tipc: narrow down interface towards struct tipc_link 2015-11-20 14:06:10 -05:00
bcast.h tipc: narrow down exposure of struct tipc_node 2015-11-20 14:06:10 -05:00
bearer.c tipc: eliminate remnants of hungarian notation 2015-11-20 14:06:10 -05:00
bearer.h tipc: eliminate remnants of hungarian notation 2015-11-20 14:06:10 -05:00
core.c tipc: create broadcast transmission link at namespace init 2015-10-24 06:56:27 -07:00
core.h tipc: reduce code dependency between binding table and node layer 2015-11-20 14:06:10 -05:00
discover.c tipc: eliminate remnants of hungarian notation 2015-11-20 14:06:10 -05:00
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 link priority propagation 2016-02-06 02:45:38 -05:00
link.h tipc: fix link attribute propagation bug 2016-02-06 02:45:27 -05:00
Makefile tipc: add ip/udp media type 2015-03-05 22:08:42 -05:00
msg.c tipc: let broadcast packet reception use new link receive function 2015-10-24 06:56:37 -07:00
msg.h tipc: let broadcast packet reception use new link receive function 2015-10-24 06:56:37 -07:00
name_distr.c tipc: reduce code dependency between binding table and node layer 2015-11-20 14:06:10 -05:00
name_distr.h tipc: reduce code dependency between binding table and node layer 2015-11-20 14:06:10 -05:00
name_table.c tipc: remove struct tipc_name_seq from struct tipc_subscription 2016-02-06 03:40:43 -05:00
name_table.h tipc: convert legacy nl name table dump to nl compat 2015-02-09 13:20:48 -08:00
net.c tipc: create broadcast transmission link at namespace init 2015-10-24 06:56:27 -07:00
net.h tipc: make tipc node table aware of net namespace 2015-01-12 16:24:32 -05:00
netlink_compat.c tipc: narrow down interface towards struct tipc_link 2015-11-20 14:06:10 -05:00
netlink.c tipc: narrow down interface towards struct tipc_link 2015-11-20 14:06:10 -05:00
netlink.h tipc: move and rename the legacy nl api to "nl compat" 2015-02-09 13:20:47 -08:00
node.c tipc: fix link attribute propagation bug 2016-02-06 02:45:27 -05:00
node.h tipc: narrow down interface towards struct tipc_link 2015-11-20 14:06:10 -05:00
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 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-12-03 21:09:12 -05:00
socket.h tipc: clean up socket layer message reception 2015-07-26 16:31:50 -07:00
subscr.c tipc: protect tipc_subscrb_get() with subscriber spin lock 2016-02-06 03:41:58 -05:00
subscr.h tipc: remove struct tipc_name_seq from struct tipc_subscription 2016-02-06 03:40:43 -05:00
sysctl.c tipc: add name distributor resiliency queue 2014-09-01 17:51:48 -07:00
udp_media.c ip_tunnel: Move stats update to iptunnel_xmit() 2015-12-25 23:32:23 -05:00