Re: [PATCH net-next] tipc: move the delivery of named messages out of nametbl lock

[David Miller <davem@davemloft.net>]

From: Ying Xue <ying.xue@windriver.com>
Date: Mon, 28 Apr 2014 18:00:10 +0800

> Commit a89778d8baf19cd7e728d81121a294a06cedaad1 ("tipc: add support
> for link state subscriptions") introduced below possible deadlock
> scenario:
> 
>        CPU0                          CPU1
> T0:   tipc_publish()                 link_timeout()
> T1:   tipc_nametbl_publish()         [grab node lock]*
> T2:   [grab nametbl write lock]*     link_state_event()
> T3:   named_cluster_distribute()     link_activate()
> T4:   [grab node lock]*              tipc_node_link_up()
> T5:                                  tipc_nametbl_publish()
> T6:                                  [grab nametble write lock]*
> 
> The opposite order of holding nametbl write lock and node lock on
> above two different paths may result in a deadlock. If we move the
> the delivery of named messages via link out of name nametbl lock,
> the reverse order of holding locks will be eliminated, as a result,
> the deadlock will be killed as well.
> 
> Signed-off-by: Ying Xue <ying.xue@windriver.com>
> Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>

Applied, thanks.

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