From: David S. Miller <davem@davemloft.net>
Date: Thu, 13 Feb 2014 22:57:11 +0000 (-0500)
Subject: Merge branch 'tipc'
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=ca52b6647ffc6bc0f4b80823006834646b3e4f04;p=deliverable%2Flinux.git

Merge branch 'tipc'

Jon Maloy says:

====================
tipc: clean up media and bearer layer

This commit series aims at facilitating future changes to the
locking policy around nodes, links and bearers.

Currently, we have a big read/write lock (net_lock) that is used for
serializing all changes to the node, link and bearer lists, as well
as to their mutual pointers and references.

But, in order to allow for concurrent access to the contents of these
structures, net_lock is only used in read mode by the data path code,
and hence a finer granular locking policy must be applied inside the
scope of net_lock: a spinlock (node_lock) for each node structure,
and another one (bearer_lock) for protection of bearer structures.

This locking policy has proved hard to maintain. We have several
times encountered contention problems between node_lock and
bearer_lock, and with the advent of the RCU locking mechanism we
feel it is anyway obsolete and ripe for improvements.

We now plan to replace net_lock with an RCU lock, as well as
getting rid of bearer_lock altogether. This will both reduce data
path overhead and make the code more manageable, while reducing the
risk of future lock contention problems.

Prior to these changes, we need to do some necessary cleanup and
code consolidation. This is what we do with this commit series,
before we finally remove bearer_lock. In a later series we will
replace net_lock with an RCU lock.

v2:
 - Re-inserted a removed kerneldoc entry in commit#5, based on
   feedback from D. Miller.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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ca52b6647ffc6bc0f4b80823006834646b3e4f04