linux/net/tipc
Ying Xue f9a2c80b8b tipc: introduce new spinlock to protect struct link_req
Currently, only 'bearer_lock' is used to protect struct link_req in
the function disc_timeout(). This is unsafe, since the member fields
'num_nodes' and 'timer_intv' might be accessed by below three different
threads simultaneously, none of them grabbing bearer_lock in the
critical region:

link_activate()
  tipc_bearer_add_dest()
    tipc_disc_add_dest()
      req->num_nodes++;

tipc_link_reset()
  tipc_bearer_remove_dest()
    tipc_disc_remove_dest()
      req->num_nodes--
      disc_update()
        read req->num_nodes
	write req->timer_intv

disc_timeout()
  read req->num_nodes
  read/write req->timer_intv

Without lock protection, the only symptom of a race is that discovery
messages occasionally may not be sent out. This is not fatal, since such
messages are best-effort anyway. On the other hand, since discovery
messages are not time critical, adding a protecting lock brings no
serious overhead either. So we add a new, dedicated spinlock in
order to guarantee absolute data consistency in link_req objects.
This also helps reduce the overall role of the bearer_lock, which
we want to remove completely in a later commit series.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-01-07 18:44:25 -05:00
..
addr.c tipc: compress out gratuitous extra carriage returns 2012-04-30 15:53:56 -04:00
addr.h tipc: compress out gratuitous extra carriage returns 2012-04-30 15:53:56 -04:00
bcast.c tipc: remove interface state mirroring in bearer 2013-12-09 20:30:29 -05:00
bcast.h tipc: cosmetic realignment of function arguments 2013-06-17 15:53:01 -07:00
bearer.c tipc: rename functions related to link failover and improve comments 2014-01-07 18:44:25 -05:00
bearer.h tipc: rename functions related to link failover and improve comments 2014-01-07 18:44:25 -05:00
config.c tipc: convert config_lock from spinlock to mutex 2013-06-17 15:53:01 -07:00
config.h tipc: Optimize re-initialization of configuration service 2012-04-26 17:19:07 -04:00
core.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-12-18 16:42:06 -05:00
core.h tipc: Use <linux/uaccess.h> instead of <asm/uaccess.h> 2013-12-16 12:48:35 -05:00
discover.c tipc: introduce new spinlock to protect struct link_req 2014-01-07 18:44:25 -05:00
discover.h tipc: rename struct link* to struct tipc_link* 2011-12-29 21:53:30 -05:00
eth_media.c tipc: eliminate code duplication in media layer 2013-12-11 00:17:43 -05:00
handler.c tipc: protect handler_enabled variable with qitem_lock spin lock 2013-12-10 22:35:49 -05:00
ib_media.c tipc: eliminate code duplication in media layer 2013-12-11 00:17:43 -05:00
Kconfig tipc: add InfiniBand media type 2013-04-17 14:18:33 -04:00
link.c tipc: remove 'has_redundant_link' flag from STATE link protocol messages 2014-01-07 18:44:25 -05:00
link.h tipc: rename functions related to link failover and improve comments 2014-01-07 18:44:25 -05:00
log.c tipc: remove print_buf and deprecated log buffer code 2012-07-13 19:34:43 -04:00
Makefile tipc: introduce new TIPC server infrastructure 2013-06-17 15:53:00 -07:00
msg.c tipc: remove iovec length parameter from all sending functions 2013-10-18 13:20:42 -04:00
msg.h tipc: message reassembly using fragment chain 2013-11-07 18:30:11 -05:00
name_distr.c tipc: eliminate an unnecessary cast of node variable 2012-11-22 14:33:28 -05:00
name_distr.h
name_table.c tipc: remove unnecessary variables and conditions 2013-12-16 12:48:35 -05:00
name_table.h tipc: cosmetic realignment of function arguments 2013-06-17 15:53:01 -07:00
net.c tipc: change tipc_net_start routine return value type 2012-08-20 02:26:30 -07:00
net.h tipc: change tipc_net_start routine return value type 2012-08-20 02:26:30 -07:00
netlink.c genetlink: only pass array to genl_register_family_with_ops() 2013-11-19 16:39:05 -05:00
node_subscr.c tipc: cosmetic realignment of function arguments 2013-06-17 15:53:01 -07:00
node_subscr.h tipc: compress out gratuitous extra carriage returns 2012-04-30 15:53:56 -04:00
node.c tipc: rename functions related to link failover and improve comments 2014-01-07 18:44:25 -05:00
node.h tipc: remove 'has_redundant_link' flag from STATE link protocol messages 2014-01-07 18:44:25 -05:00
port.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-01-06 17:37:45 -05:00
port.h tipc: fix deadlock during socket release 2013-12-29 22:24:07 -05:00
ref.c tipc: use standard printk shortcut macros (pr_err etc.) 2012-07-13 19:24:44 -04:00
ref.h tipc: cleanup function namespace 2010-10-16 11:13:24 -07:00
server.c tipc: fix oops when creating server socket fails 2013-08-01 15:54:33 -07:00
server.h tipc: introduce new TIPC server infrastructure 2013-06-17 15:53:00 -07:00
socket.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-01-06 17:37:45 -05:00
subscr.c tipc: cosmetic realignment of function arguments 2013-06-17 15:53:01 -07:00
subscr.h tipc: cosmetic realignment of function arguments 2013-06-17 15:53:01 -07:00
sysctl.c tipc: change socket buffer overflow control to respect sk_rcvbuf 2013-06-17 15:53:00 -07:00