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tipc: change to use register_pernet_device 

This patch is to fix a dst defcnt leak, which can be reproduced by doing:

  # ip net a c; ip net a s; modprobe tipc
  # ip net e s ip l a n eth1 type veth peer n eth1 netns c
  # ip net e c ip l s lo up; ip net e c ip l s eth1 up
  # ip net e s ip l s lo up; ip net e s ip l s eth1 up
  # ip net e c ip a a 1.1.1.2/8 dev eth1
  # ip net e s ip a a 1.1.1.1/8 dev eth1
  # ip net e c tipc b e m udp n u1 localip 1.1.1.2
  # ip net e s tipc b e m udp n u1 localip 1.1.1.1
  # ip net d c; ip net d s; rmmod tipc

and it will get stuck and keep logging the error:

  unregister_netdevice: waiting for lo to become free. Usage count = 1

The cause is that a dst is held by the udp sock's sk_rx_dst set on udp rx
path with udp_early_demux == 1, and this dst (eventually holding lo dev)
can't be released as bearer's removal in tipc pernet .exit happens after
lo dev's removal, default_device pernet .exit.

 "There are two distinct types of pernet_operations recognized: subsys and
  device.  At creation all subsys init functions are called before device
  init functions, and at destruction all device exit functions are called
  before subsys exit function."

So by calling register_pernet_device instead to register tipc_net_ops, the
pernet .exit() will be invoked earlier than loopback dev's removal when a
netns is being destroyed, as fou/gue does.

Note that vxlan and geneve udp tunnels don't have this issue, as the udp
sock is released in their device ndo_stop().

This fix is also necessary for tipc dst_cache, which will hold dsts on tx
path and I will introduce in my next patch.

Reported-by: Li Shuang <shuali@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2019-06-20 18:39:28 +08:00 committed by David S. Miller
parent 8ac8a01092
commit c492d4c74d
1 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/tipc/core.c
View File

@ -134,7 +134,7 @@ static int __init tipc_init(void)
if (err)
goto out_sysctl;
err = register_pernet_subsys(&tipc_net_ops);
err = register_pernet_device(&tipc_net_ops);
if (err)
goto out_pernet;
@ -142,7 +142,7 @@ static int __init tipc_init(void)
if (err)
goto out_socket;
err = register_pernet_subsys(&tipc_topsrv_net_ops);
err = register_pernet_device(&tipc_topsrv_net_ops);
if (err)
goto out_pernet_topsrv;
@ -153,11 +153,11 @@ static int __init tipc_init(void)
pr_info("Started in single node mode\n");
return 0;
out_bearer:
unregister_pernet_subsys(&tipc_topsrv_net_ops);
unregister_pernet_device(&tipc_topsrv_net_ops);
out_pernet_topsrv:
tipc_socket_stop();
out_socket:
unregister_pernet_subsys(&tipc_net_ops);
unregister_pernet_device(&tipc_net_ops);
out_pernet:
tipc_unregister_sysctl();
out_sysctl:
@ -172,9 +172,9 @@ static int __init tipc_init(void)
static void __exit tipc_exit(void)
{
tipc_bearer_cleanup();
unregister_pernet_subsys(&tipc_topsrv_net_ops);
unregister_pernet_device(&tipc_topsrv_net_ops);
tipc_socket_stop();
unregister_pernet_subsys(&tipc_net_ops);
unregister_pernet_device(&tipc_net_ops);
tipc_netlink_stop();
tipc_netlink_compat_stop();
tipc_unregister_sysctl();