[RFC Patch net-next 0/6] net_sched: really switch to RCU for tc actions

[Cong Wang <xiyou.wangcong@gmail.com>]

Currently there are only two tc actions lockless:
gact and mirred. But they are questionable because
we don't have anything to prevent a parallel update
on an existing tc action in hash table while reading
it on fast path, this could be a problem when a tc
action becomes complex.

This patchset introduces a few new tc action API's
based on RCU so that the fast path could now really
be protected by RCU and we can update existing tc
actions safely and race-freely.

Obviously this is still _not_ complete yet, I only
modified mirred action to show the use case of
the new API's, all the rest actions could switch to
the new API's too. The new API's are a bit ugly too,
any suggestion to improve them is welcome.

I tested mirred action with a few test cases, so far
so good, at least no obvious bugs. ;)


Cong Wang (6):
  net_sched: use RCU for action hash table
  net_sched: introduce tcf_hash_replace()
  net_sched: return NULL in tcf_hash_check()
  net_sched: introduce tcf_hash_copy()
  net_sched: use rcu in fast path
  net_sched: switch to RCU API for act_mirred

 include/net/act_api.h  |  3 +++
 net/sched/act_api.c    | 59 +++++++++++++++++++++++++++++++++++++++++++-------
 net/sched/act_mirred.c | 41 ++++++++++++++++-------------------
 3 files changed, 73 insertions(+), 30 deletions(-)

-- 
2.1.0